0001656423-20-000007 | 10-K | XBRL Viewer

2,960,562

2,717,076

2,602,076

Expenses

Rental

1,050,010

979,151

929,977

General and administrative

1,984

1,604

668

140,777

121,722

113,715

677,764

645,649

617,547

1,914,925

1,791,579

1,693,966

46,592

2,222

11,232

709

182,356

7,663

18,939

10,823

5,783

6,417

(1,865)

3,678

(24,038)

(11,812)

(Losses) gains from early extinguishments of debt

(412,717)

(378,168)

(374,481)

(29,540)

(16,490)

496

Net income attributable to noncontrolling interests

651,999

712,563

562,481

Noncontrolling interests in property partnerships

(71,120)

(62,909)

(47,832)

Noncontrolling interest - common units of the Operating Partnership

(59,345)

(66,807)

(52,210)

Net income attributable to the Company

521,534

582,847

462,439

Net income attributable to the Company's common shareholders / unitholders

(10,500)

$ 511,034

$ 572,347

$ 451,939

Basic earnings per common share / unit attributable to the Company

Net income (in dollars per share / unit)

$ 3.31

$ 3.71

$ 2.93

Weighted average number of common shares / units outstanding (in shares / units)

154,582

154,427

154,190

Diluted earnings per common share / unit attributable to the Company

Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)

$ 3.30

$ 3.70

$ 2.93

Weighted average number of common and common equivalent shares / units outstanding (in shares / units)

154,883

154,682

154,390

Revenue

Lease

$ 2,758,014

Base rent

$ 2,103,723

$ 2,049,368

Recoveries from tenants

402,066

367,500

2,960,562

2,717,076

2,602,076

Expenses

Rental

1,050,010

979,151

929,977

General and administrative

1,984

1,604

668

140,777

121,722

113,715

669,956

637,891

1,907,117

1,783,821

1,685,826

46,592

2,222

11,232

858

190,716

8,240

18,939

10,823

5,783

6,417

(1,865)

3,678

(22,272)

(10,181)

(Losses) gains from early extinguishments of debt

(412,717)

(378,168)

(374,481)

(29,540)

(16,490)

496

Net income attributable to noncontrolling interests

661,722

730,312

571,198

Noncontrolling interests in property partnerships

(71,120)

(62,909)

(47,832)

Net income attributable to the Company

590,602

667,403

523,366

Net income attributable to the Company's common shareholders / unitholders

(10,500)

$ 580,102

$ 656,903

$ 512,866

Basic earnings per common share / unit attributable to the Company

Net income (in dollars per share / unit)

$ 3.37

$ 3.82

$ 2.99

Weighted average number of common shares / units outstanding (in shares / units)

172,200

171,912

171,661

Diluted earnings per common share / unit attributable to the Company

Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)

$ 3.36

$ 3.81

$ 2.98

Weighted average number of common and common equivalent shares / units outstanding (in shares / units)

172,501

172,167

171,861

Parking and Other [Member]

Revenue

Parking and Other [Member] | Boston Properties Limited Partnership

$ 103,534

$ 107,421

$ 105,000

Revenue

103,534

107,421

105,000

Hotel [Member]

Revenue

^[1]

48,589

49,118

45,603

Expenses

Hotel [Member] | Boston Properties Limited Partnership

34,004

33,863

32,059

Revenue

48,589

49,118

45,603

Expenses

Real Estate, Other [Member]

34,004

33,863

32,059

Revenue

Real Estate, Other [Member] | Boston Properties Limited Partnership

10,386

9,590

Revenue

Management Service [Member]

10,386

9,590

Revenue

40,039

45,158

34,605

Expenses

Management Service [Member] | Boston Properties Limited Partnership

10,386

9,590

Revenue

40,039

45,158

34,605

Expenses

$ 10,386

$ 9,590

$ 0

[1]	Rental Revenue is equal to Total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

Consolidated Statements Of Comprehensive Income - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Effective portion of interest rate contracts

$ 651,999

$ 712,563

$ 562,481

Other comprehensive income (loss):

(6,751)

(3,096)

(6,133)

Amortization of interest rate contracts

^[1]

6,664

6,033

Other comprehensive income (loss)

(87)

3,568

(100)

Comprehensive Income

651,912

716,131

562,381

Comprehensive income attributable to noncontrolling interests

(130,465)

(129,716)

(100,042)

Other comprehensive income (loss) attributable to noncontrolling interests

(507)

(880)

1,922

Comprehensive income attributable to the Company

520,940

585,535

464,261

Effective portion of interest rate contracts

661,722

730,312

571,198

Other comprehensive income (loss):

(6,751)

(3,096)

(6,133)

Amortization of interest rate contracts

^[2]

6,664

6,033

Other comprehensive income (loss)

(87)

3,568

(100)

Comprehensive Income

661,635

733,880

571,098

Comprehensive income attributable to noncontrolling interests

(71,696)

(63,485)

(45,704)

Comprehensive income attributable to the Company

$ 589,939

$ 670,395

$ 525,394

[1]	Amounts reclassified from comprehensive income primarily to interest expense within Boston Properties, Inc.’s Consolidated Statements of Operations
[2]	Amounts reclassified from comprehensive income primarily to interest expense within Boston Properties Limited Partnership’s Consolidated Statements of Operations.

Consolidated Statements Of Stockholders' Equity - USD ($)	Total	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-In Capital [Member]	Dividends In Excess Of Earnings [Member]	Treasury Stock, At Cost [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]	Noncontrolling interest - property partnerships [Member]
Equity, shares at Dec. 31, 2016		153,790,000
Equity, value at Dec. 31, 2016	$ 7,931,924,000	$ 1,538,000	$ 200,000,000	$ 6,333,424,000	$ (693,694,000)	$ (2,722,000)	$ (52,251,000)	$ 614,982,000	$ 1,530,647,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of a change in accounting principle	(2,035,000)				(272,000)			(1,763,000)
Redemption of operating partnership units to common stock, shares		495,000
Redemption of operating partnership units to common stock, value	0	$ 5,000		16,911,000				(16,916,000)
Allocated net income for the year	562,481,000				462,439,000			52,210,000	47,832,000
Dividends/distributions declared	(535,310,000)				(480,816,000)			(54,494,000)
Shares issued pursuant to stock purchase plan, shares		6,000
Shares issued pursuant to stock purchase plan, value	795,000			795,000
Net activity from stock option and incentive plan, shares		34,000
Net activity from stock option and incentive plan, value	37,292,000			3,899,000				33,393,000
Proceeds from noncontrolling interest including a contribution related to the repayment of a members' note payable	161,585,000								161,585,000
Contributions from noncontrolling interests in property partnerships	52,009,000								161,585,000
Distributions to noncontrolling interests in property partnerships	(54,176,000)								(54,176,000)
Effective portion of interest rate contracts	(6,133,000)						(3,305,000)	(375,000)	(2,453,000)
Amortization of interest rate contracts	6,033,000						5,127,000	581,000	325,000
Reallocation of noncontrolling interest	0			22,879,000				(22,879,000)
Equity, shares at Dec. 31, 2017		154,325,000
Equity, value at Dec. 31, 2017	8,102,456,000	$ 1,543,000	200,000,000	6,377,908,000	(712,343,000)	(2,722,000)	(50,429,000)	604,739,000	1,683,760,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of a change in accounting principle	5,496,000				4,933,000			563,000
Redemption of operating partnership units to common stock, shares		83,000
Redemption of operating partnership units to common stock, value	0	$ 2,000		2,878,000				(2,880,000)
Allocated net income for the year	712,563,000				582,847,000			66,807,000	62,909,000
Dividends/distributions declared	(613,702,000)				(550,971,000)			(62,731,000)
Shares issued pursuant to stock purchase plan, shares		6,000
Shares issued pursuant to stock purchase plan, value	797,000			797,000
Net activity from stock option and incentive plan, shares		44,000
Net activity from stock option and incentive plan, value	38,590,000			1,729,000				36,861,000
Contributions from noncontrolling interests in property partnerships	46,701,000								46,701,000
Distributions to noncontrolling interests in property partnerships	(82,501,000)								(82,501,000)
Effective portion of interest rate contracts	(3,096,000)						(2,781,000)	(315,000)
Amortization of interest rate contracts	6,664,000						5,469,000	619,000	576,000
Reallocation of noncontrolling interest	$ 0			24,311,000				(24,311,000)
Equity, shares at Dec. 31, 2018	154,458,478	154,458,000
Equity, value at Dec. 31, 2018	$ 8,213,968,000	$ 1,545,000	200,000,000	6,407,623,000	(675,534,000)	(2,722,000)	(47,741,000)	619,352,000	1,711,445,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of a change in accounting principle	(4,379,000)				(3,864,000)			(445,000)	(70,000)
Redemption of operating partnership units to common stock, shares		145,000
Redemption of operating partnership units to common stock, value	0	$ 2,000		4,883,000				(4,885,000)
Allocated net income for the year	651,999,000				521,534,000			59,345,000	71,120,000
Dividends/distributions declared	(671,893,000)				(602,659,000)			(69,234,000)
Shares issued pursuant to stock purchase plan, shares		6,000
Shares issued pursuant to stock purchase plan, value	688,000			688,000
Net activity from stock option and incentive plan, shares		181,000
Net activity from stock option and incentive plan, value	45,000,000	$ 1,000		8,771,000				36,228,000
Sale of an interest in property partnerships	0			(4,216,000)					4,216,000
Acquisition of noncontrolling interest in property partnership	(186,963,000)			(162,462,000)					(24,501,000)
Contributions from noncontrolling interests in property partnerships	35,816,000								35,816,000
Distributions to noncontrolling interests in property partnerships	(69,913,000)								(69,913,000)
Effective portion of interest rate contracts	(6,751,000)						(6,060,000)	(691,000)
Amortization of interest rate contracts	6,664,000						5,466,000	622,000	576,000
Reallocation of noncontrolling interest	$ 0			39,432,000				(39,432,000)
Equity, shares at Dec. 31, 2019	154,790,298	154,790,000
Equity, value at Dec. 31, 2019	$ 8,014,236,000	$ 1,548,000	$ 200,000,000	$ 6,294,719,000	$ (760,523,000)	$ (2,722,000)	$ (48,335,000)	$ 600,860,000	$ 1,728,689,000

Consolidated Statement of Capital and Noncontrolling Interests Statement - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock, Shares, Outstanding	154,790,298	154,458,478
Cumulative effect of a change in accounting principle	$ (4,379,000)	$ 5,496,000	$ (2,035,000)
Effective portion of interest rate contracts	(6,751,000)	(3,096,000)	(6,133,000)
Amortization of interest rate contracts	6,664,000	6,664,000	6,033,000
Acquisition of noncontrolling interest in property partnership	(186,963,000)
Sale of an interest in property partnerships	0
Contributions from noncontrolling interests in property partnerships	35,816,000	46,701,000	52,009,000
Distributions to noncontrolling interests in property partnerships	$ (69,913,000)	$ (82,501,000)	$ (54,176,000)
General Partner [Member]
Common Stock, Shares, Outstanding	1,727,000	1,722,000	1,720,000	1,718,000
Contributions, units	3,000	1,000
Conversion of redeemable partnership units	2,000	1,000	2,000
Limited Partner [Member]
Common Stock, Shares, Outstanding	153,063,000	152,736,000	152,606,000	152,072,000
Contributions, units	185,000	49,000	40,000
Conversion of redeemable partnership units	142,000	81,000	494,000
Boston Properties Limited Partnership
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	$ 2,468,753,000	$ 2,000,591,000
Contributions from noncontrolling interests in property partnerships	35,816,000	46,701,000	$ 52,009,000
Partners' Capital General and Limited Partners) [Member]
Beginning Balance	3,380,175,000	4,054,996,000	3,664,436,000	$ 3,670,345,000
Cumulative effect of a change in accounting principle	(3,864,000)	4,933,000	(272,000)
Contributions, value	17,115,000	1,642,000	4,937,000
Allocated net income for the period	520,757,000	590,096,000	460,656,000
Distributions	(592,159,000)	(540,471,000)	(470,316,000)
Unearned compensation	(7,655,000)	884,000	(243,000)
Conversion of redeemable partnership units, value	4,885,000	2,880,000	16,916,000
Adjustment to reflect redeemable partnership units at redemption value	(447,222,000)	330,596,000	(17,587,000)
Acquisition of noncontrolling interest in property partnership	(162,462,000)
Sale of an interest in property partnerships	(4,216,000)
Preferred Units [Member]
Beginning Balance	193,623,000	193,623,000	193,623,000	193,623,000
Allocated net income for the period	10,500,000	10,500,000	10,500,000
Distributions	(10,500,000)	(10,500,000)	(10,500,000)
Accumulated Other Comprehensive Loss [Member]
Beginning Balance	(48,335,000)	(47,741,000)	(50,429,000)	(52,251,000)
Effective portion of interest rate contracts	(6,060,000)	(2,781,000)	(3,305,000)
Amortization of interest rate contracts	5,466,000	5,469,000	5,127,000
Noncontrolling interest - property partnerships [Member]
Beginning Balance	1,728,689,000	1,711,445,000	1,683,760,000	1,530,647,000
Cumulative effect of a change in accounting principle	(70,000)
Allocated net income for the period	71,120,000	62,909,000	47,832,000
Effective portion of interest rate contracts			(2,453,000)
Amortization of interest rate contracts	576,000	576,000	325,000
Acquisition of noncontrolling interest in property partnership	(24,501,000)
Sale of an interest in property partnerships	4,216,000
Contributions from noncontrolling interests in property partnerships	35,816,000	46,701,000	161,585,000
Distributions to noncontrolling interests in property partnerships	(69,913,000)	(82,501,000)	(54,176,000)
Total Capital [Member]
Beginning Balance	5,254,152,000	5,912,323,000	5,491,390,000	5,342,364,000
Cumulative effect of a change in accounting principle	(3,934,000)	4,933,000	(272,000)
Contributions, value	17,115,000	1,642,000	4,937,000
Allocated net income for the period	602,377,000	663,505,000	518,988,000
Distributions	(602,659,000)	(550,971,000)	(480,816,000)
Unearned compensation	(7,655,000)	884,000	(243,000)
Conversion of redeemable partnership units, value	4,885,000	2,880,000	16,916,000
Adjustment to reflect redeemable partnership units at redemption value	(447,222,000)	330,596,000	(17,587,000)
Effective portion of interest rate contracts	(6,060,000)	(2,781,000)	(5,758,000)
Amortization of interest rate contracts	6,042,000	6,045,000	5,452,000
Acquisition of noncontrolling interest in property partnership	(186,963,000)
Sale of an interest in property partnerships	0
Contributions from noncontrolling interests in property partnerships	35,816,000	46,701,000	161,585,000
Distributions to noncontrolling interests in property partnerships	(69,913,000)	(82,501,000)	(54,176,000)
Noncontrolling interest - Redeemable partnership units [Member]
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	2,468,753,000	2,000,591,000	2,292,263,000	$ 2,262,040,000
Cumulative effect of a change in accounting principle	(445,000)	563,000	(1,763,000)
Contributions, value	34,217,000	34,680,000	31,743,000
Allocated net income for the period	59,345,000	66,807,000	52,210,000
Distributions	(69,234,000)	(62,731,000)	(54,494,000)
Unearned compensation	2,011,000	2,181,000	1,650,000
Conversion of redeemable partnership units, value	(4,885,000)	(2,880,000)	(16,916,000)
Adjustment to reflect redeemable partnership units at redemption value	447,222,000	(330,596,000)	17,587,000
Effective portion of interest rate contracts	(691,000)	(315,000)	(375,000)
Amortization of interest rate contracts	$ 622,000	$ 619,000	$ 581,000

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Net income	$ 651,999	$ 712,563	$ 562,481
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	677,764	645,649	617,547
Amortization of right-of-use assets - operating leases	2,412
Impairment losses	24,038	11,812	0
Non-cash compensation expense	40,958	40,117	35,361
Income from unconsolidated joint ventures	(46,592)	(2,222)	(11,232)
Distributions of net cash flow from operations of unconsolidated joint ventures	17,155	6,703	26,858
(Gains) losses from investments in securities	(6,417)	1,865	(3,678)
Non-cash portion of interest expense	22,254	21,303	(1,284)
Settlement of accreted debt discount on redemption of unsecured senior notes	(763)	(483)	(1,980)
Losses (gains) from early extinguishments of debt	29,540	16,490	(496)
Gains on sales of real estate	(709)	(182,356)	(7,663)
Change in assets and liabilities:
Tenant and other receivables, net	(24,876)	29,204	2,433
Note receivable	4	(13)	0
Accrued rental income, net	(56,817)	(43,662)	(58,355)
Prepaid expenses and other assets	2,965	12,472	51,425
Lease liabilities - operating leases	1,616
Accounts payable and accrued expenses	12,627	1,353	10,482
Accrued interest payable	858	5,237	(160,521)
Other liabilities	(49,569)	4,955	(44,970)
Tenant leasing costs	(117,282)	(130,742)	(104,429)
Total adjustments	529,166	437,682	349,498
Net cash provided by operating activities	1,181,165	1,150,245	911,979
Cash flows from investing activities:
Acquisitions of real estate	(149,031)	0	(15,953)
Construction in progress	(546,060)	(694,791)	(608,404)
Building and other capital improvements	(180,556)	(189,771)	(222,482)
Tenant improvements	(251,831)	(210,034)	(205,331)
Right of use assets - finance leases	(5,152)	0	0
Proceeds from sales of real estate	90,824	455,409	29,810
Capital contributions to unconsolidated joint ventures	(87,392)	(345,717)	(109,015)
Capital distributions from unconsolidated joint ventures	136,807	0	251,000
Cash and cash equivalents deconsolidated	(24,112)	0	0
Deposit on capital lease	0	(13,615)	0
Issuance of related party note receivable	0	(80,000)	0
Issuance of note receivable	0	(19,455)	0
Proceeds from note receivable	3,544	0	0
Investments in securities, net	(2,132)	(902)	(1,669)
Net cash used in investing activities	(1,015,091)	(1,098,876)	(882,044)
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	0	2,300,000
Repayments of mortgage notes payable	(46,173)	(18,634)	(1,317,653)
Proceeds from unsecured senior notes	1,548,106	996,410	847,935
Redemption of unsecured senior notes	(699,237)	(699,517)	(848,020)
Borrowings on unsecured line of credit	380,000	745,000	580,000
Repayments of unsecured line of credit	(380,000)	(790,000)	(535,000)
Proceeds from unsecured term loan	0	500,000	0
Repayments of mezzanine notes payable	0	0	(306,000)
Repayments of outside members’ notes payable	0	0	(70,424)
Payments on finance lease obligations	(502)	0	0
Payments on capital lease obligations	0	(1,353)	(493)
Payments on real estate financing transactions	0	(960)	(2,840)
Deposit on mortgage note payable interest rate lock	0	0	(23,200)
Return of deposit on mortgage note payable interest rate lock	0	0	23,200
Deferred financing costs	(13,213)	(8,362)	(50,705)
Debt prepayment and extinguishment costs	(28,716)	(15,973)	(12,784)
Net proceeds from equity transactions	13,710	(730)	241
Dividends and distributions	(666,294)	(587,628)	(526,578)
Contributions from noncontrolling interests in property partnerships	35,816	46,701	52,009
Distributions to noncontrolling interests in property partnerships	(69,913)	(82,501)	(54,342)
Acquisition of noncontrolling interest in property partnership	(186,963)	0	0
Net cash (used in) provided by financing activities	(113,379)	82,453	55,346
Net increase (decrease) in cash and cash equivalents	52,695	133,822	85,281
Cash and cash equivalents and cash held in escrows, beginning of year	639,191	505,369	420,088
Cash and cash equivalents and cash held in escrows, end of year	691,886	639,191	505,369
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of year	543,359	434,767	356,914
Cash held in escrows, beginning of period	95,832	70,602	63,174
Cash and cash equivalents, end of year	644,950	543,359	434,767
Cash held in escrows,end of period	46,936	95,832	70,602
Supplemental disclosures:
Cash paid for interest	439,059	416,019	598,486
Interest capitalized	54,911	65,766	61,070
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(129,831)	(135,431)	(124,891)
Change in real estate included in accounts payable and accrued expenses	89,245	(44,866)	27,978
Real estate acquired through capital leases	0	12,397	28,962
Real estate acquired through capital lease	287,540	0	0
Prepaid rent reclassified to right of use asset	15,000	0	0
Building and other capital improvements deconsolidated	(12,767)	0	0
Right of use asset - finance lease deconsolidated	(135,004)	0	0
Investment in unconsolidated joint venture recorded on deconsolidation	29,246	0	0
Lease liability - finance lease deconsolidation	119,534	0	0
Outside members’ notes payable contributed to noncontrolling interests in property partnerships	0	0	109,576
Dividends and distributions declared but not paid	170,713	165,114	139,040
Conversions of noncontrolling interests to stockholders’ equity	4,885	2,880	16,916
Issuance of restricted securities to employees and directors	37,622	37,052	35,989
Boston Properties Limited Partnership
Net income	661,722	730,312	571,198
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	669,956	637,891	609,407
Amortization of right-of-use assets - operating leases	2,412
Impairment losses	22,272	10,181	0
Non-cash compensation expense	40,958	40,117	35,361
Income from unconsolidated joint ventures	(46,592)	(2,222)	(11,232)
Distributions of net cash flow from operations of unconsolidated joint ventures	17,155	6,703	26,858
(Gains) losses from investments in securities	(6,417)	1,865	(3,678)
Non-cash portion of interest expense	22,254	21,303	(1,284)
Settlement of accreted debt discount on redemption of unsecured senior notes	(763)	(483)	(1,980)
Losses (gains) from early extinguishments of debt	29,540	16,490	(496)
Gains on sales of real estate	(858)	(190,716)	(8,240)
Change in assets and liabilities:
Tenant and other receivables, net	(24,876)	29,204	2,433
Note receivable	4	(13)	0
Accrued rental income, net	(56,817)	(43,662)	(58,355)
Prepaid expenses and other assets	2,965	12,472	51,425
Lease liabilities - operating leases	1,616
Accounts payable and accrued expenses	12,627	1,353	10,482
Accrued interest payable	858	5,237	(160,521)
Other liabilities	(49,569)	4,955	(44,970)
Tenant leasing costs	(117,282)	(130,742)	(104,429)
Total adjustments	519,443	419,933	340,781
Net cash provided by operating activities	1,181,165	1,150,245	911,979
Cash flows from investing activities:
Acquisitions of real estate	(149,031)	0	(15,953)
Construction in progress	(546,060)	(694,791)	(608,404)
Building and other capital improvements	(180,556)	(189,771)	(222,482)
Tenant improvements	(251,831)	(210,034)	(205,331)
Right of use assets - finance leases	(5,152)	0	0
Proceeds from sales of real estate	90,824	455,409	29,810
Capital contributions to unconsolidated joint ventures	(87,392)	(345,717)	(109,015)
Capital distributions from unconsolidated joint ventures	136,807	0	251,000
Cash and cash equivalents deconsolidated	(24,112)	0	0
Deposit on capital lease	0	(13,615)	0
Issuance of related party note receivable	0	(80,000)	0
Issuance of note receivable	0	(19,455)	0
Proceeds from note receivable	3,544	0	0
Investments in securities, net	(2,132)	(902)	(1,669)
Net cash used in investing activities	(1,015,091)	(1,098,876)	(882,044)
Cash flows from financing activities:
Proceeds from mortgage notes payable	0	0	2,300,000
Repayments of mortgage notes payable	(46,173)	(18,634)	(1,317,653)
Proceeds from unsecured senior notes	1,548,106	996,410	847,935
Redemption of unsecured senior notes	(699,237)	(699,517)	(848,020)
Borrowings on unsecured line of credit	380,000	745,000	580,000
Repayments of unsecured line of credit	(380,000)	(790,000)	(535,000)
Proceeds from unsecured term loan	0	500,000	0
Repayments of mezzanine notes payable	0	0	(306,000)
Repayments of outside members’ notes payable	0	0	(70,424)
Payments on finance lease obligations	(502)
Payments on capital lease obligations		(1,353)	(493)
Payments on real estate financing transactions	0	(960)	(2,840)
Deposit on mortgage note payable interest rate lock	0	0	(23,200)
Return of deposit on mortgage note payable interest rate lock	0	0	23,200
Deferred financing costs	(13,213)	(8,362)	(50,705)
Debt prepayment and extinguishment costs	(28,716)	(15,973)	(12,784)
Net proceeds from equity transactions	13,710	(730)	241
Dividends and distributions	(666,294)	(587,628)	(526,578)
Contributions from noncontrolling interests in property partnerships	35,816	46,701	52,009
Distributions to noncontrolling interests in property partnerships	(69,913)	(82,501)	(54,342)
Acquisition of noncontrolling interest in property partnership	(186,963)	0
Net cash (used in) provided by financing activities	(113,379)	82,453	55,346
Net increase (decrease) in cash and cash equivalents	52,695	133,822	85,281
Cash and cash equivalents and cash held in escrows, beginning of year	639,191	505,369	420,088
Cash and cash equivalents and cash held in escrows, end of year	691,886	639,191	505,369
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of year	543,359	434,767	356,914
Cash held in escrows, beginning of period	95,832	70,602	63,174
Cash and cash equivalents, end of year	644,950	543,359	434,767
Cash held in escrows,end of period	46,936	95,832	70,602
Supplemental disclosures:
Cash paid for interest	439,059	416,019	598,486
Interest capitalized	54,911	65,766	61,070
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(129,253)	(135,431)	(123,714)
Change in real estate included in accounts payable and accrued expenses	89,245	44,866	27,978
Real estate acquired through capital leases	0	12,397	28,962
Real estate acquired through capital lease	287,540	0	0
Prepaid rent reclassified to right of use asset	15,000	0	0
Building and other capital improvements deconsolidated	(12,767)	0	0
Right of use asset - finance lease deconsolidated	(135,004)	0	0
Investment in unconsolidated joint venture recorded on deconsolidation	29,246	0	0
Lease liability - finance lease deconsolidation	119,534	0	0
Outside members’ notes payable contributed to noncontrolling interests in property partnerships	0	0	109,576
Dividends and distributions declared but not paid	170,713	165,114	139,040
Conversions of noncontrolling interests to stockholders’ equity	4,885	2,880	16,916
Issuance Of Restricted Units To Employees And Directors	$ 37,622	$ 37,052	$ 35,989

Organization

12 Months Ended

Dec. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization

1. Organization

Boston Properties, Inc., a Delaware corporation, is a fully integrated, self-administered and self-managed real estate investment trust (“REIT”). Boston Properties, Inc. is the sole general partner of Boston Properties Limited Partnership, its operating partnership and at December 31, 2019 owned an approximate 89.6% (89.7% at December 31, 2018) general and limited partnership interest in Boston Properties Limited Partnership. Unless stated otherwise or the context requires, the “Company” refers to Boston Properties, Inc. and its subsidiaries, including Boston Properties Limited Partnership and its consolidated subsidiaries. Partnership interests in Boston Properties Limited Partnership include:


•	common units of partnership interest (also referred to as “OP Units”),


•	long term incentive units of partnership interest (also referred to as “LTIP Units”), and


•	preferred units of partnership interest (also referred to as “Preferred Units”).

Unless specifically noted otherwise, all references to OP Units exclude units held by Boston Properties, Inc. A holder of an OP Unit may present such OP Unit to Boston Properties Limited Partnership for redemption at any time (subject to restrictions agreed upon at the time of issuance of OP Units to particular holders that may restrict such redemption right for a period of time, generally one year from issuance). Upon presentation of an OP Unit for redemption, Boston Properties Limited Partnership is obligated to redeem the OP Unit for cash equal to the value of a share of common stock of Boston Properties, Inc. (“Common Stock”). In lieu of a cash redemption, Boston Properties, Inc. may elect to acquire the OP Unit for one share of Common Stock. Because the number of shares of Common Stock outstanding at all times equals the number of OP Units that Boston Properties, Inc. owns, one share of Common Stock is generally the economic equivalent of one OP Unit, and the quarterly distribution that may be paid to the holder of an OP Unit equals the quarterly dividend that may be paid to the holder of a share of Common Stock.

The Company uses LTIP Units as a form of equity-based award for annual long-term incentive equity compensation. The Company has also issued LTIP Units to employees in the form of (1) 2012 outperformance plan awards (“2012 OPP Units”) and (2) 2013, 2014, 2015, 2016, 2017, 2018 and 2019 multi-year, long-term incentive program awards (also referred to as “MYLTIP Units”), each of which, upon the satisfaction of certain performance and vesting conditions, is convertible into one OP Unit. The three-year measurement periods for the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units expired on February 6, 2015, February 4, 2016, February 3, 2017, February 4, 2018 and February 9, 2019, respectively, and Boston Properties, Inc.’s total stockholder return (“TSR”) was sufficient for employees to earn and therefore become eligible to vest in a portion of the awards. Unless and until they are earned, the rights, preferences and privileges of the 2017 MYLTIP Units, 2018 MYLTIP Units and 2019 MYLTIP Units differ from other LTIP Units granted to employees (including the 2012 OPP Units, the 2013 MYLTIP Units, the 2014 MYLTIP Units, the 2015 MYLTIP Units and the 2016 MYLTIP Units, which have been earned). Therefore, unless specifically noted otherwise, all references to LTIP Units exclude the 2017 MYLTIP Units, 2018 MYLTIP Units and 2019 MYLTIP Units. LTIP Units (including the earned 2012 OPP Units, the 2013 MYLTIP Units, the 2014 MYLTIP Units, the 2015 MYLTIP Units and 2016 MYLTIP Units), whether vested or not, will receive the same quarterly per unit distributions as OP Units, which equal per share dividends on Common Stock (See Notes 10, 16 and 19).

At December 31, 2019, there was one series of Preferred Units outstanding (i.e., Series B Preferred Units). The Series B Preferred Units were issued to Boston Properties, Inc. on March 27, 2013 in connection with the issuance of 80,000 shares (8,000,000 depositary shares each representing 1/100th of a share) of 5.25% Series B Cumulative Redeemable Preferred Stock (the “Series B Preferred Stock”). Boston Properties, Inc. contributed the net proceeds from the offering to Boston Properties Limited Partnership in exchange for 80,000 Series B Preferred Units having terms and preferences generally mirroring those of the Series B Preferred Stock (See Note 11).

Properties

At December 31, 2019, the Company owned or had interests in a portfolio of 196 commercial real estate properties (the “Properties”) aggregating approximately 52.0 million net rentable square feet of primarily Class A office properties, including 11 properties under construction/redevelopment totaling approximately 5.5 million net rentable square feet. At December 31, 2019, the Properties consisted of:


•	177 office properties (including nine properties under construction/redevelopment);


•	twelve retail properties;


•	six residential properties (including two properties under construction); and


•	one hotel.

The Company considers Class A office properties to be well located buildings that are professionally managed and maintained, attract high-quality tenants and command upper-tier rental rates, and that are modern structures or have been modernized to compete with newer buildings.

Basis of Presentation

The accompanying consolidated financial statements are presented using the accrual basis of accounting in conformity with accounting principles generally accepted in the United States of America. Boston Properties, Inc. does not have any other significant assets, liabilities or operations, other than its investment in Boston Properties Limited Partnership, nor does it have employees of its own. Boston Properties Limited Partnership, not Boston Properties, Inc., generally executes all significant business relationships other than transactions involving securities of Boston Properties, Inc. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income.

Variable Interest Entities (VIEs)

Consolidated VIEs are those for which the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE. The Company has determined that it is the primary beneficiary for six of the eight entities that are VIEs (see “New Accounting Pronouncements Issued but not yet Adopted—Consolidation” within Note 2).

Consolidated Variable Interest Entities

As of December 31, 2019, Boston Properties, Inc. has identified six consolidated VIEs, including Boston Properties Limited Partnership. Excluding Boston Properties Limited Partnership, the VIEs consisted of the following five in-service properties: 767 Fifth Avenue (the General Motors Building), Time Square Tower, 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street.

The Company consolidates these VIEs because it is the primary beneficiary. The third parties’ interests in these consolidated entities (i.e., excluding Boston Properties Limited Partnership’s interest) are reflected as noncontrolling interest in property partnerships in the accompanying Consolidated Financial Statements (See Note 10).

In addition, Boston Properties, Inc.’s only significant asset is its investment in Boston Properties Limited Partnership and, consequently, substantially all of Boston Properties, Inc.’s assets and liabilities are the assets and liabilities of Boston Properties Limited Partnership.

Variable Interest Entities Not Consolidated

The Company has determined that Platform 16 Holdings LP and the landlord entity for its Platform 16 ground lease are VIEs. The Company does not consolidate these entities as the Company does not have the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and, therefore, the Company is not considered to be the primary beneficiary.

Summary Of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Basis Of Presentation And Summary Of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Real Estate

Upon acquisitions of real estate, the Company assesses whether the transaction should be accounted for as an asset acquisition or as a business combination by applying a screen to determine whether the integrated set of assets and activities acquired meets the definition of a business. Acquisitions of integrated sets of assets and activities that do not meet the definition of a business are accounted for as asset acquisitions. The Company’s acquisitions of real estate or in-substance real estate generally will not meet the definition of a business because substantially all of the fair value is concentrated in a single identifiable asset or group of similar identifiable assets (i.e. land, buildings, and related intangible assets) or because the acquisition does not include a substantive process in the form of an acquired workforce or an acquired contract that cannot be replaced without significant cost, effort or delay.

The Company assesses the fair value of acquired tangible and intangible assets (including land, buildings, tenant improvements, “above-” and “below-market” leases, leasing and assumed financing origination costs, acquired in-place leases, other identified intangible assets and assumed liabilities) and allocates the purchase price to the acquired assets and assumed liabilities, including land and buildings as if vacant. The Company assesses fair value based on estimated cash flow projections that utilize discount and/or capitalization rates that it deems appropriate, as well as available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known and anticipated trends, and market and economic conditions.

The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant. The Company also considers an allocation of purchase price of other acquired intangibles, including acquired in-place leases that may have a customer relationship intangible value, including (but not limited to) the nature and extent of the existing relationship with the tenants, the tenants’ credit quality and expectations of lease renewals. Based on its acquisitions to date, the Company’s allocation to customer relationship intangible assets has been immaterial.

The Company records acquired “above-” and “below-market” leases at their fair values (using a discount rate which reflects the risks associated with the leases acquired) equal to the difference between (1) the contractual amounts to be paid pursuant to each in-place lease and (2) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the initial term plus the term of any below-market fixed rate renewal options for below-market leases. Acquired “above-” and “below-market” lease values have been reflected within Prepaid Expenses and Other Assets and Other Liabilities, respectively, in the Company’s Consolidated Balance Sheets. Other intangible assets acquired include amounts for in-place lease values that are based on the Company’s evaluation of the specific characteristics of each tenant’s lease. Factors to be considered include estimates of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, the Company considers leasing commissions, legal and other related expenses.

Management reviews its long-lived assets for impairment following the end of each quarter and when there is an event or change in circumstances that indicates carrying amounts may not be recoverable. An impairment loss is recognized if the carrying amount of an asset is not recoverable and exceeds its fair value. The evaluation of anticipated cash flows is subjective and is based in part on assumptions regarding anticipated hold periods, future occupancy, future rental rates, future capital requirements, discount rates and capitalization rates that could differ materially from actual results in future periods. Because cash flows on properties considered to be “long-lived assets to be held and used” are considered on an undiscounted basis to determine whether an asset has been impaired, the Company’s established strategy of holding properties over the long term directly decreases the likelihood of recording an impairment loss. If the Company’s strategy changes or market conditions otherwise dictate an earlier sale date, an impairment loss may be recognized and such loss could be material. If the Company determines that an impairment has occurred, the affected assets must be reduced to their fair value.

Guidance in Accounting Standards Codification (“ASC”) 360 “Property Plant and Equipment” (“ASC 360”) requires that qualifying assets and liabilities and the results of operations that have been sold, or otherwise qualify as “held for sale,” be presented as discontinued operations in all periods presented if the property operations are expected to be eliminated and the Company will not have significant continuing involvement following the sale. Discontinued operations presentation applies only to disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results (e.g., a disposal of a major geographical area, a major line of business, a

major equity method investment or other major parts of an entity). The components of the property’s net income that are reflected as discontinued operations include the net gain (or loss) upon the disposition of the property held for sale, operating results, depreciation and interest expense (if the property is subject to a secured loan). The Company generally considers assets to be “held for sale” when the transaction has been approved by Boston Properties, Inc.’s Board of Directors, or a committee thereof, and there are no known significant contingencies relating to the sale, such that a sale of the property within one year is considered probable. Following the classification of a property as “held for sale,” no further depreciation is recorded on the assets, and the asset is written down to the lower of carrying value or fair market value, less cost to sell.

Real estate is stated at depreciated cost. A variety of costs are incurred in the acquisition, development and leasing of properties. The cost of buildings and improvements includes the purchase price of property, legal fees and other acquisition costs. The Company capitalizes acquisition costs that it incurs to effect an asset acquisition and expenses acquisition costs that it incurs to effect a business combination, including legal, due diligence and other closing related costs. Costs directly related to the development of properties are capitalized. Capitalized development costs include interest, internal wages, property taxes, insurance, and other project costs incurred during the period of development. After the determination is made to capitalize a cost, it is allocated to the specific component of the project that benefited from the investment. Determination of when a development project commences and capitalization begins, and when a development project is substantially complete and held available for occupancy and capitalization must cease, involves a degree of judgment. The Company’s capitalization policy on development properties follows the guidance in ASC 835-20 “Capitalization of Interest” and ASC 970 “Real Estate-General.” The costs of land and buildings under development include specifically identifiable costs.

Capitalized costs include pre-construction costs necessary to the development of the property, development costs, construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. The Company begins the capitalization of costs during the pre-construction period, which it defines as activities that are necessary for the development of the property. The Company considers a construction project as substantially complete and held available for occupancy upon the completion of tenant improvements, but no later than one year from cessation of major construction activity. The Company ceases capitalization on the portion (1) substantially completed, (2) occupied or held available for occupancy, and capitalizes only those costs associated with the portion under construction or (3) if activities necessary for the development of the property have been suspended. Interest costs capitalized for the years ended December 31, 2019, 2018 and 2017 were approximately $54.9 million, $65.8 million and $61.1 million, respectively. Salaries and related costs capitalized for the years ended December 31, 2019, 2018 and 2017 were approximately $10.4 million, $12.5 million and $13.2 million, respectively.

Expenditures for repairs and maintenance are charged to operations as incurred. Significant betterments are capitalized. When assets are sold or retired, their costs and related accumulated depreciation are removed from the accounts with the resulting gains or losses reflected in net income or loss for the period.

The Company computes depreciation and amortization on properties using the straight-line method based on estimated useful asset lives. The Company allocates the acquisition cost of real estate to its components and depreciates or amortizes these assets (or liabilities) over their useful lives. The amortization of acquired “above-” and “below-market” leases and acquired in-place leases is recorded as an adjustment to revenue and depreciation and amortization, respectively, in the Consolidated Statements of Operations.

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:



Land improvements		25 to 40 years
Buildings and improvements		10 to 40 years
Tenant improvements		Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment		3 to 7 years

Cash and Cash Equivalents

Cash and cash equivalents consist of cash on hand and investments with maturities of three months or less from the date of purchase. The majority of the Company’s cash and cash equivalents are held at major commercial banks which may at times exceed the Federal Deposit Insurance Corporation limit of $250,000.

Cash Held in Escrows

Escrows include amounts established pursuant to various agreements for security deposits, property taxes, insurance and other costs. Escrows also include cash held by qualified intermediaries for possible investments in like-kind exchanges in accordance with Section 1031 of the Internal Revenue Code, as amended (the “Code”), in connection with sales of the Company’s properties.

Investments in Securities

The Company accounts for investments in equity securities at fair value, with gains or losses resulting from changes in fair value recognized currently in earnings. The Company maintains deferred compensation plans that are designed to allow officers and non-employee directors of Boston Properties, Inc. to defer a portion of the officer’s current income or the non-employee director’s current compensation on a pre-tax basis and receive a tax-deferred return on these deferrals based on the performance of specific investments selected by the officer or non-employee director. The Company’s obligation under the plans is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2019 and 2018, the Company had maintained approximately $36.7 million and $28.2 million, respectively, in separate accounts, which are not restricted as to their use. The Company recognized gains (losses) of approximately $6.4 million, $(1.9) million and $3.7 million on its investments in the accounts associated with the Company’s deferred compensation plans during the years ended December 31, 2019, 2018 and 2017, respectively.

Tenant and Other Receivables

Tenant and other accounts receivable, other than accrued rents receivable, are expected to be collected within one year.

Notes Receivable

The Company accounts for notes receivable at their unamortized cost, net of any unamortized deferred fees or costs, premiums or discounts and an allowance for loan losses (see “New Accounting Pronouncements Issued but not yet Adopted—Financial Instruments - Credit Losses”). Loan fees and direct costs associated with loans originated by the Company are deferred and amortized over the term of the note as interest income.

Deferred Charges

Deferred charges include leasing costs and certain financing fees. Leasing costs include acquired intangible in-place lease values and direct and incremental fees and costs incurred in the successful negotiation of leases, including brokerage and other costs which have been deferred and are being amortized on a straight-line basis over the terms of the respective leases. Unamortized leasing costs are charged to expense upon the early termination of the lease. Fully amortized deferred leasing costs are removed from the books upon the expiration of the lease. The Company did not capitalize any external legal costs and internal leasing salaries and related costs for the year ended December 31, 2019 (see “New Accounting Pronouncements Adopted—Leases”). Internal leasing salaries and related costs capitalized for the years ended December 31, 2018 and 2017 were approximately $5.4 million and $5.0 million, respectively. Financing fees included in deferred charges consist of external fees and costs incurred to obtain the Company’s revolving facility and if applicable, the delayed draw facility and construction financing arrangements where there are not sufficient amounts outstanding. Such financing costs have been deferred and are being amortized over the terms of the respective financing and included within interest expense. Unamortized financing costs are charged to expense upon the early repayment or significant modification of the financing. Fully amortized deferred financing costs are removed from the books upon the maturity of the debt.

External fees and costs incurred to obtain mortgage financings and unsecured senior notes have been deferred and are presented as direct deductions from the carrying amounts of the corresponding debt liability. Such financing costs are being amortized over the terms of the respective financing and included within interest expense. Unamortized financing costs are charged to expense upon the early repayment or significant modification of the financing.

Investments in Unconsolidated Joint Ventures

The Company consolidates VIEs in which it is considered to be the primary beneficiary. VIEs are entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or that the holders of the equity investment at risk do not have substantive participating rights. The primary beneficiary is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken

together, most significantly impact the variable interest entity’s performance, and (2) the obligation to absorb losses and the right to receive the returns from the variable interest entity that could potentially be significant to the VIE. For ventures that are not VIEs, the Company consolidates entities for which it has significant decision making control over the ventures’ operations. The Company’s judgment with respect to its level of influence or control of an entity involves the consideration of various factors including the form of the Company’s ownership interest, its representation in the entity’s governance, the size of its investment (including loans), estimates of future cash flows, its ability to participate in policy making decisions and the rights of the other investors to participate in the decision making process and to replace the Company as manager and/or liquidate the venture, if applicable. The Company’s assessment of its influence or control over an entity affects the presentation of these investments in the Company’s consolidated financial statements. In addition to evaluating control rights, the Company consolidates entities in which the outside partner has no substantive kick-out rights to remove the Company as the managing member.

Accounts of the consolidated entity are included in the accounts of the Company and the noncontrolling interest is reflected on the Consolidated Balance Sheets as a component of equity or in temporary equity between liabilities and equity. Investments in unconsolidated joint ventures are recorded initially at cost, and subsequently adjusted for equity in earnings and cash contributions and distributions. Any difference between the carrying amount of these investments on the balance sheet and the underlying equity in net assets is amortized as an adjustment to equity in earnings of unconsolidated joint ventures over the life of the related asset. Under the equity method of accounting, the net equity investment of the Company is reflected within the Consolidated Balance Sheets, and the Company’s share of net income or loss from the joint ventures is included within the Consolidated Statements of Operations. The joint venture agreements may designate different percentage allocations among investors for profits and losses; however, the Company’s recognition of joint venture income or loss generally follows the joint venture’s distribution priorities, which may change upon the achievement of certain investment return thresholds. The Company may account for cash distributions in excess of its investment in an unconsolidated joint venture as income when the Company is not the general partner in a limited partnership and when the Company has neither the requirement nor the intent to provide financial support to the joint venture. The Company classifies distributions received from equity method investees within its Consolidated Statements of Cash Flows using the nature of the distribution approach, which classifies the distributions received on the basis of the nature of the activity or activities of the investee that generated the distribution as either a return on investment (classified as cash inflows from operating activities) or a return of investment (classified as cash inflows from investing activities). The Company’s investments in unconsolidated joint ventures are reviewed for impairment periodically and the Company records impairment charges when events or circumstances change indicating that a decline in the fair values below the carrying amounts has occurred and such decline is other-than-temporary. The evaluation of fair value is subjective and is based in part on assumptions regarding future occupancy, future rental rates, future capital requirements, discount rates and capitalization rates that could differ materially from actual results in future periods. The ultimate realization of the investment in unconsolidated joint ventures is dependent on a number of factors, including the performance of each investment and market conditions. The Company will record an impairment charge if it determines that a decline in the fair value below the carrying amount of an investment in an unconsolidated joint venture is other-than-temporary.

To the extent that the Company contributed assets to a joint venture, the Company’s investment in the joint venture was recorded at the Company’s cost basis in the assets that were contributed to the joint venture. To the extent that the Company’s cost basis is different than the basis reflected at the joint venture level, the basis difference is amortized over the life of the related asset and included in the Company’s share of equity in net income of the joint venture. In accordance with the provisions of ASC 610-20 “Gains and Losses from the Derecognition of Nonfinancial Assets” (“ASC 610-20”), the Company will recognize a full gain on both the retained and sold portions of real estate contributed or sold to a joint venture by recognizing its new equity method investment interest at fair value.

The combined summarized financial information of the unconsolidated joint ventures is disclosed in Note 5.

Revenue Recognition

In general, the Company commences lease/rental revenue recognition when the tenant takes possession of the leased space and the leased space is substantially ready for its intended use. Contractual lease/rental revenue is reported on a straight-line basis over the terms of the respective leases. The impact of the straight-line rent adjustment increased revenue by approximately $58.4 million, $51.9 million and $54.8 million for the years ended December 31, 2019, 2018 and 2017, respectively, as the revenue recorded exceeded amounts billed. Accrued rental income, as reported on the Consolidated Balance Sheets, represents cumulative lease/rental income earned in excess of rent payments received pursuant to the terms of the individual lease agreements. The Company maintains an allowance against accrued rental income for future potential tenant credit losses. The credit assessment is based on the

estimated accrued rental income that is recoverable over the term of the lease. The Company also maintains an allowance for doubtful accounts for estimated losses resulting from the inability of tenants to make required rent payments. The computation of this allowance is based on the tenants’ payment history and current credit status, as well as certain industry or geographic specific credit considerations. If the Company’s estimates of collectability differ from the cash received, then the timing and amount of the Company’s reported revenue could be impacted. The credit risk is mitigated by the high quality of the Company’s existing tenant base, reviews of prospective tenants’ risk profiles prior to lease execution and consistent monitoring of the Company’s portfolio to identify potential problem tenants.

In accordance with ASC 805, the Company recognizes acquired in-place “above-” and “below-market” leases at their fair values as rental revenue over the original term of the respective leases. The impact of the acquired in-place “above-” and “below-market” leases increased revenue by approximately $20.9 million, $23.8 million and $23.5 million for the years ended December 31, 2019, 2018 and 2017, respectively. The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2020	$	5,440	$	10,673
2021	3,054		6,455
2022	357		5,699
2023	183		5,558
2024	135		4,043

Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized as revenue in the period during which the expenses are incurred (see “New Accounting Pronouncements Adopted—Leases”). The Company recognizes these reimbursements on a gross basis, as the Company obtains control of the goods and services before they are transferred to the tenant. The Company also receives reimbursements of payroll and payroll related costs from unconsolidated joint venture entities and third party property owners in connection with management services contracts which the Company reflects on a gross basis instead of on a net basis as the Company has determined that it is the principal and not the agent under these arrangements in accordance with the guidance in ASC 606 “Revenue from Contracts with Customers” (“ASC 606”).

The Company’s parking revenue is derived primarily from monthly and transient daily parking. In addition, the Company has certain lease arrangements for parking accounted for under the guidance in ASC 842 “Leases” (“ASC 842”). The monthly and transient daily parking revenue falls within the scope of ASC 606 and is accounted for at the point in time when control of the goods or services transfers to the customer and the Company’s performance obligation is satisfied.

The Company’s hotel revenue is derived from room rentals and other sources such as charges to guests for telephone service, movie and vending commissions, meeting and banquet room revenue and laundry services. Hotel revenue is recognized as the hotel rooms are occupied and the services are rendered to the hotel customers.

The Company earns management and development fees. Development and management services revenue is earned from unconsolidated joint venture entities and third-party property owners. The Company determined that the performance obligations associated with its development services contracts are satisfied over time and that the Company would recognize its development services revenue under the output method evenly over time from the development commencement date through the substantial completion date of the development management services project due to the stand-ready nature of the contracts. Significant judgments impacting the amount and timing of revenue recognized from the Company’s development services contracts include estimates of total development project costs from which the fees are typically derived and estimates of the period of time until substantial completion of the development project, the period of time over which the development services are required to be performed. The Company recognizes development fees earned from unconsolidated joint venture projects equal to its cost plus profit to the extent of the third party partners’ ownership interest. Property management fees are recorded and earned based on a percentage of collected rents at the properties under management, and not on a straight-line basis, because such fees are contingent upon the collection of rents.

Gains on sales of real estate are recognized pursuant to the provisions included in ASC 610-20. Under ASC 610-20, the Company must first determine whether the transaction is a sale to a customer or non-customer. The Company typically sells real estate on a selective basis and not within the ordinary course of its business and therefore expects that its sale transactions will not be contracts with customers. The Company next determines whether it has a controlling financial interest in the property after the sale, consistent with the consolidation model in ASC 810 “Consolidation” (“ASC 810”). If the Company determines that it does not have a controlling financial interest in the real estate, it evaluates whether a contract exists under ASC 606 and whether the buyer has obtained control of the asset that was sold. The Company recognizes a full gain on sale of real estate when the derecognition criteria under ASC 610-20 have been met.

Earnings Per Share

Basic earnings per share (“EPS”) is computed by dividing net income available to common shareholders, as adjusted for undistributed earnings (if any) of certain securities issued by Boston Properties Limited Partnership, by the weighted average number of shares of Common Stock outstanding during the year. Diluted EPS reflects the potential dilution that could occur from shares issuable in connection with awards under stock-based compensation plans, including upon the exercise of stock options, and securities of Boston Properties Limited Partnership that are exchangeable for Common Stock.

Earnings Per Common Unit

Basic earnings per common unit is computed by dividing net income available to common unitholders, as adjusted for undistributed earnings (if any) of certain securities issued by Boston Properties Limited Partnership, by the weighted average number of common units outstanding during the year. Diluted earnings per common unit reflects the potential dilution that could occur from units issuable in connection with awards under Boston Properties, Inc.’s stock-based compensation plans, including upon the exercise of stock options, and conversion of preferred units of Boston Properties Limited Partnership.

Fair Value of Financial Instruments

The carrying values of cash and cash equivalents, marketable securities, escrows, receivables, accounts payable, accrued expenses and other assets and liabilities are reasonable estimates of their fair values because of the short maturities of these instruments.

The Company follows the authoritative guidance for fair value measurements when valuing its financial instruments for disclosure purposes. Boston Properties Limited Partnership determines the fair value of its unsecured senior notes using market prices. The inputs used in determining the fair value of Boston Properties Limited Partnership’s unsecured senior notes is categorized at a Level 1 basis (as defined in ASC 820 “Fair Value Measurements and Disclosures” (“ASC 820”)) due to the fact that it uses quoted market rates to value these instruments. However, the inputs used in determining the fair value could be categorized at a Level 2 basis (as defined in ASC 820) if trading volumes are low. The Company determines the fair value of its related party note receivable, note receivable and mortgage notes payable using discounted cash flow analysis by discounting the spread between the future contractual interest payments and hypothetical future interest payments on note receivables / mortgage debt based on current market rates for similar securities. In determining the current market rates, the Company adds its estimates of market spreads to the quoted yields on federal government treasury securities with similar maturity dates to its debt. The inputs used in determining the fair value of the Company’s related party note receivable, note receivable, and mortgage notes payable are categorized at a Level 3 basis (as defined in ASC 820) due to the fact that the Company considers the rates used in the valuation techniques to be unobservable inputs. To the extent that there are outstanding borrowings under the unsecured line of credit or unsecured term loan, the Company utilizes a discounted cash flow methodology in order to estimate the fair value. To the extent that credit spreads have changed since the origination, the net present value of the difference between future contractual interest payments and future interest payments based on the Company’s estimate of a current market rate would represent the difference between the book value and the fair value. The Company’s estimate of a current market rate is based upon the rate, considering current market conditions and Boston Properties Limited Partnership’s specific credit profile, at which it estimates it could obtain similar borrowings. To the extent there are outstanding borrowings, this current market rate is estimated and therefore would be primarily based upon a Level 3 input (see “New Accounting Pronouncements Issued but not yet Adopted—Fair Value Measurement”).

Because the Company’s valuations of its financial instruments are based on these types of estimates, the actual fair values of its financial instruments may differ materially if the Company’s estimates do not prove to be accurate, and the Company’s estimated fair values for these instruments as of the end of the applicable reporting period are not necessarily indicative of estimated or actual fair values in future reporting periods. The following table presents the aggregate carrying value of the Company’s related party note receivable, note receivable, mortgage notes payable, net, unsecured senior notes, net, unsecured line of credit and unsecured term loan, net and the Company’s corresponding estimate of fair value as of December 31, 2019 and December 31, 2018 (in thousands):



	December 31, 2019				December 31, 2018
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable	$	80,000	$	81,931	$	80,000	$	80,000
Note receivable	15,920		14,978		19,468		19,468
Total	$	95,920	$	96,909	$	99,468	$	99,468

Mortgage notes payable, net	$	2,922,408	$	2,984,956	$	2,964,572	$	2,903,925
Unsecured senior notes, net	8,390,459		8,826,375		7,544,697		7,469,338
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	498,939		500,561		498,488		500,783
Total	$	11,811,806	$	12,311,892	$	11,007,757	$	10,874,046

The Company uses interest rate swap agreements to manage its interest rate risk. The valuation of these instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. To comply with the provisions of ASC 820, the Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. Although the Company determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by the Company and its counterparties. The Company assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and determined that the credit valuation adjustments were not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy.

Derivative Instruments and Hedging Activities

Derivative instruments and hedging activities require management to make judgments on the nature of its derivatives and their effectiveness as hedges. These judgments determine if the changes in fair value of the derivative instruments are reported in the Consolidated Statements of Operations as a component of net income or as a component of comprehensive income and as a component of equity on the Consolidated Balance Sheets. While management believes its judgments are reasonable, a change in a derivative’s effectiveness as a hedge could materially affect expenses, net income and equity. The Company accounts for both the effective and ineffective portions of changes in the fair value of a derivative in other comprehensive income (loss) and subsequently reclassifies the fair value of the derivative to earnings over the term that the hedged transaction affects earnings and in the same line item as the hedged transaction within the statements of operations.

Stock-Based Employee Compensation Plans

At December 31, 2019, the Company has a stock-based employee compensation plan. The Company accounts for the plan under the guidance in ASC 718 “Compensation – Stock Compensation” (“ASC 718”), which revised the fair value based method of accounting for share-based payment liabilities, forfeitures and modifications of stock-based awards and clarified previous guidance in several areas, including measuring fair value, classifying an award as equity or as a liability and attributing compensation cost to reporting periods.

Use of Estimates in the Preparation of Financial Statements

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. These estimates include such items as depreciation and allowances for doubtful accounts. Actual results could differ from those estimates.

Out-of-Period Adjustment

During the year ended December 31, 2019, the Company recorded a change in the balance sheet classification of deferred stock units held by non-employee directors of Boston Properties, Inc. that are outstanding under Boston Properties, Inc.’s 1997 Stock Option and Incentive Plan and 2012 Stock Option and Incentive Plan (the “Plans”). The reclassification resulted from a modification to the terms of the non-employee director compensation program to provide, subject to certain conditions, the non-employee directors holding these units with the ability to elect, following cessation of their service on the Company’s Board of Directors, to diversify their investment elections into non-employer securities, which will ultimately be settled in cash. The modification required a change to the classification of these deferred stock units from permanent equity to temporary equity on the Consolidated Balance Sheets of Boston Properties, Inc. and Boston Properties Limited Partnership within Redeemable Deferred Stock Units. During the year ended December 31, 2019, the Company recorded a change in the balance sheet classification of certain deferred stock units outstanding to correct the approximately $8.4 million overstatement of each of Additional Paid-in Capital of Boston Properties, Inc. and Partners’ Capital of Boston Properties Limited Partnership, the approximately $8.1 million understatement of each of Redeemable Deferred Stock Units of Boston Properties, Inc. and Boston Properties Limited Partnership, and the approximately $0.3 million understatement of each of Accounts Payable and Accrued Expenses of Boston Properties, Inc. and Boston Properties Limited Partnership in the year ended December 31, 2018. Because this adjustment was not material to the prior year’s consolidated financial statements and the impact of recording the adjustment in the year ended December 31, 2019 was not material to Boston Properties, Inc.’s or Boston Properties Limited Partnership’s consolidated financial statements, the Company recorded the related adjustment during the year ended December 31, 2019. The out-of-period adjustment was identified and recorded during the three months ended September 30, 2019.

New Accounting Pronouncements Adopted

Leases

General Adoption

In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-02, which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). ASU 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease for accounting purposes is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to the prior guidance in ASC 840 -“Leases” (“Topic 840”). ASU 2016-02 requires lessors to account for leases using an approach that is substantially equivalent to Topic 840 for sales-type leases, direct financing leases and operating leases. ASU 2016-02 supersedes previous leasing standards.

On July 30, 2018, the FASB issued ASU 2018-11, “Leases (Topic 842): Targeted Improvements” (“ASU 2018-11”), that (1) simplifies transition requirements for both lessees and lessors by adding an option that permits an organization to apply the transition provisions of the new standard at its adoption date instead of at the earliest comparative period presented in its financial statements and (2) allows lessors to elect, as a practical expedient, by class of underlying asset, to not separate nonlease components from the associated lease component and, instead, to account for those components as a single component if the nonlease components otherwise would be accounted for under the revenue guidance in ASC 606 that was adopted on January 1, 2018, and both of the following are met:

(1) the timing and pattern of transfer of the nonlease component(s) and associated lease components are the same; and

(2) the lease component, if accounted for separately, would be classified as an operating lease.

If the nonlease component or components associated with the lease component are the predominant component of the combined component, an entity is required to account for the combined component in accordance with ASC 606.

The Company adopted ASU 2016-02 and ASU 2018-11 effective January 1, 2019. For purposes of transition, the Company elected the practical expedient package, which has been applied consistently to all of its leases, but did not elect the hindsight practical expedient. The practical expedient package did not require the Company to reassess the following: (i) whether an expired or existing contract meets the definition of a lease; (ii) the lease classification at the adoption date for existing leases; and (iii) whether costs previously capitalized as initial direct costs would continue to be amortized. This allows the Company to continue to account for its ground leases as operating leases. However, as of January 1, 2019, any new or modified ground leases may be classified as financing leases unless they meet certain conditions. The Company also elected to apply the transition provisions as of the adoption date, January 1, 2019, and not change its comparative statements. The Company recorded an adjustment to the opening balance of retained earnings related to initial direct costs that, as of January 1, 2019, had not started to amortize and are no longer allowed to be capitalized in accordance with ASU 2016-02, totaling approximately $3.9 million to Dividends in Excess of Earnings of Boston Properties, Inc. and Partners’ Capital of Boston Properties Limited Partnership, approximately $0.4 million to Noncontrolling interests - Common Units of Boston Properties, Inc. and Noncontrolling Interest - Redeemable Partnership Units of Boston Properties Limited Partnership and $70,000 to Noncontrolling Interests - Property Partnerships of Boston Properties, Inc. and Noncontrolling Interests in Property Partnerships of Boston Properties Limited Partnership on the corresponding Consolidated Balance Sheets.

The Company made the policy election, when it is the lessee, to not apply the revenue recognition requirements of Topic 842 to short-term leases. This policy election is made by class of underlying assets and as described below, the Company considers real estate to be a class of underlying assets, and will not be further delineating it into specific uses of the real estate asset as the risk profiles are similar in nature. The Company will recognize the lease payments in net income on a straight-line basis over the lease term.

Lease payments from operating leases are recognized on a straight-line basis over the term of the leases. The cumulative difference between lease revenue recognized under this method and the contractual lease payment terms is recorded as deferred rent receivable on the Company’s Consolidated Balance Sheets. The Company reviews its trade accounts receivable, including its straight-line rent receivable, related to base rents, straight-line rent, expense reimbursements and other revenues for collectability. The Company analyzes its accounts receivable, customer creditworthiness and current economic trends when evaluating the adequacy of the collectability of the lessee’s total accounts receivable balance on a lease-by-lease basis. In addition, tenants in bankruptcy are analyzed and considerations are made in connection with the expected recovery of pre-petition and post-petition claims. If a lessee’s accounts receivable balance is considered uncollectible, the Company will write-off the receivable balances associated with the lease to Lease revenue and cease to recognize lease income, including straight-line rent, unless cash is received. If the Company subsequently determines that it is probable it will collect substantially all the remaining lessee’s lease payments under the lease term, the Company will then reinstate the straight-line balance, adjusting for the amount related to the period when the lease payments were considered not probable. The Company’s reported net earnings are directly affected by management’s estimate of the collectability of its trade accounts receivable.

In January 2018, the FASB issued ASU 2018-01, “Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842” (“ASU 2018-01”), which provides an optional transition practical expedient to not evaluate, under Topic 842, existing or expired land easements that were not previously accounted for as leases under the leases guidance in Topic 840. An entity that elects this practical expedient should evaluate new or modified land easements under Topic 842 beginning at the date that the entity adopts Topic 842. An entity that does not elect this practical expedient should evaluate all existing or expired land easements in connection with the adoption of the new lease requirements in Topic 842 to assess whether they meet the definition of a lease. The effective date and transition requirements for ASU 2018-01 are the same as the effective date and transition requirements in ASU 2016-02. The Company adopted ASU 2018-01 on January 1, 2019.

Lessee

For leases in which the Company is the lessee (generally ground leases), on January 1, 2019, the Company recognized a right-of-use asset and a lease liability of approximately $151.8 million and $199.3 million, respectively. The lease liability was equal to the present value of the minimum lease payments in accordance with Topic ASC 840. In addition, the Company did not know the rate implicit in any of its ground leases that were classified as operating leases, and accordingly used the Company’s incremental borrowing rate (“IBR”) to determine the net present value of the minimum lease payments.

In order to determine the IBR, the Company utilized a market-based approach to estimate the incremental borrowing rate for each individual lease. The approach required significant judgment. Therefore, the Company utilized different data sets to estimate base IBRs via an analysis of the following weighted-components:


•	the interpolated rates from yields on outstanding U.S. Treasury issuances for up to 30 years and for years 31 and beyond, longer-term publicly traded educational institution debt issued by high credit quality educational institutions with maturity dates up to 2116,


•	observable mortgage rates spread over U.S. Treasury issuances, and


•	unlevered property yields and discount rates.

The Company then applied adjustments to account for considerations related to term and interpolated the IBR.

The Company has four non-cancelable ground lease obligations, which were classified as operating leases, with various initial term expiration dates through 2114. The Company recognizes ground rent expense on a straight-line basis over the term of the respective ground lease agreements. None of the amounts disclosed below for these ground leases contain variable payments, extension options or residual value guarantees. One of the ground leases does have an extension option. However, lease payments for this ground lease are based on fair market value and as such have not been included in the analysis below.

The Company has four finance lease obligations with various initial term expiration dates through 2094, see Note 3.

The following table provides lease cost information for the Company’s operating and finance leases for the year ended December 31, 2019 (in thousands):



Lease costs
Operating lease costs	$	14,573
Finance lease costs
Amortization of right of use asset (1)	$	29
Interest on lease liabilities (2)	$	47

_______________

(1)

The finance leases relate to either land, buildings or assets that remain in development. For land leases classified as finance leases because of a purchase option that the Company views as an economic incentive, the Company follows its existing policy and does not depreciate land because it is assumed to have an indefinite life. For all other finance leases, the Company would amortize the right of use asset over the shorter of the useful life of the asset or the lease term. If the finance lease relates to a property under development, the amortization of the right of use asset may be eligible for capitalization. For assets under development, depreciation may commence once the asset is placed in-service and depreciation would be recognized in accordance with the Company’s policy.


(2)	Three of the finance leases relate to assets under development and as such, the entire interest amount was capitalized.

The following table provides other quantitative information for the Company’s operating and finance leases as of December 31, 2019:



	December 31, 2019
Other information
Weighted-average remaining lease term (in years)
Operating leases	51
Finance leases	71
Weighted-average discount rate
Operating leases	5.7	%
Finance leases	6.2	%

The following table provides a maturity analysis for the Company’s future contractual minimum lease payments to be made by the Company as of December 31, 2018, under non-cancelable ground leases which expire on various dates through 2114:



Years Ending December 31,	(in thousands)
2019	$	11,425
2020	18,425
2021	25,310
2022	8,894
2023	9,084
Thereafter	567,232

The following table provides a maturity analysis for the Company’s future minimum lease payments, as of December 31, 2018, related to the four capital leases, through 2036:



Years Ending December 31,	(in thousands)
2019	$	1,441
2020	12,682
2021	2,123
2022	1,253
2023	944
Thereafter	73,241
Total expected minimum lease payments	91,684
Interest portion	(27,497		)
Present value of expected net minimum lease payments	$	64,187

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2019 (in thousands):



	Operating			Finance
2020	$	10,050		$	834
2021	24,973			5,960
2022	18,041			10,208
2023	10,322			9,708
2024 (1)	9,277			48,518
Thereafter	557,954			1,383,242
Total lease payments	630,617			1,458,470
Less: interest portion	(430,437		)	(1,234,428		)
Present value of lease payments	$	200,180		$	224,042

_______________


(1)	Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company is reasonably certain it will exercise.

Lessor

The Company leases primarily Class A office, retail and residential space to tenants. These leases may contain extension and termination options that are predominately at the sole discretion of the tenant, provided certain conditions are satisfied. In a few instances, the leases also contain purchase options, which would be exercisable at fair market value. Also, certain of the Company’s leases include rental payments that are based on a percentage of the tenant sales in excess of contractual amounts.

ASU 2018-11 provides lessors a practical expedient to not separate nonlease components from the associated lease component if certain criteria stated above are met for each class of underlying assets. The guidance in Topic 842 defines “underlying asset” as “an asset that is the subject of a lease for which a right to use that asset has been conveyed to a lessee. The underlying asset could be a physically distinct portion of a single asset.” Based on the above guidance, the Company considers real estate assets as a class of underlying assets and will not be further delineating it into specific uses of the real estate asset as the risk profiles are similar in nature.

Lease components are elements of an arrangement that provide the customer with the right to use an identified asset. Nonlease components are distinct elements of a contract that are not related to securing the use of the leased asset and revenue is recognized in accordance with ASC 606. The Company considers common area maintenance (CAM) and service income associated with tenant work orders to be nonlease components because they represent delivery of a separate service but are not considered a cost of securing the identified asset. In the case of the Company’s business, the identified asset would be the leased real estate (office, retail or residential).

The Company assessed and concluded that the timing and pattern of transfer for nonlease components and the associated lease component are the same. The Company determined that the predominant component was the lease component and as such its leases will continue to qualify as operating leases and the Company has made a policy election to account for and present the lease component and the nonlease component as a single component in the revenue section of the Consolidated Statements of Operations labeled Lease. Prior to the adoption of Topic 842, nonlease components had been included within Recoveries from Tenants Revenue, Parking and Other Revenue and Development and Management Services Revenue on the Company’s Consolidated Statements of Operations.

In addition, under ASU 2016-02, lessors will only capitalize incremental direct leasing costs. As a result, starting January 1, 2019, the Company no longer capitalizes non-incremental legal costs and internal leasing wages. These costs are expensed as incurred. The expensing of these items is included within General and Administrative Expense on the Consolidated Statements of Operations.

The following table summarizes the components of lease revenue recognized during the year ended December 31, 2019 included within the Company’s Consolidated Statements of Operations (in thousands):



Lease Revenue
Fixed contractual payments	$	2,261,260
Variable lease payments	496,754
	$	2,758,014

The Company’s properties are leased to tenants under operating leases with initial term expiration dates ranging from 2020 to 2049. For the future contractual lease payments to be received by the Company, refer to Note 12.

New Accounting Pronouncements Issued but not yet Adopted

Financial Instruments - Credit Losses

In June 2016, the FASB issued ASU 2016-13, “Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments” (“ASU 2016-13”). ASU 2016-13 is intended to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date by replacing the current incurred loss impairment methodology with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. In November 2018, the FASB issued ASU 2018-19, “Codification Improvements to Topic 326, Financial Instruments - Credit Losses” (“ASU 2018-19”). ASU 2018-19 clarifies that receivables arising from operating leases are not within the scope of ASC 326-20, “Financial Instruments - Credit Losses - Measured at Amortized Cost,” which addresses financial assets measured at amortized cost basis, including net investments in leases arising from sales-type and direct financing leases. Instead, impairment of receivables arising from operating leases should be accounted for in accordance with ASC 842. ASU 2016-13 and ASU 2018-19 are effective for the Company for reporting periods beginning after December 15, 2019, with early adoption permitted. ASU 2016-13 and ASU 2018-19 are applicable to the Company with respect to (1) certain of its accounts receivable, except for amounts arising from operating leases accounted for under ASC 842, (2) its related party note receivable, (3) its note receivable and (4) certain of its off-balance sheet credit exposures. The Company adopted ASU 2016-13 and ASU 2018-19 effective January 1, 2020 using the modified retrospective approach. The

adoption of ASU 2016-13 and ASU 2018-19 did not have a material impact on the Company’s consolidated financial statements.

Fair Value Measurement

In August 2018, the FASB issued ASU 2018-13, “Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement” (“ASU 2018-13”). ASU 2018-13 is intended to improve the effectiveness of disclosures required by entities regarding recurring and nonrecurring fair value measurements. ASU 2018-13 is effective for the Company for reporting periods beginning after December 15, 2019, with early adoption permitted. The adoption of ASU 2018-13 will not have a material impact on the Company’s consolidated financial statements.

Derivatives and Hedging

In October 2018, the FASB issued ASU 2018-16, “Derivatives and Hedging (Topic 815): Inclusion of the Secured Overnight Financing Rate (SOFR) Overnight Index Swap (OIS) Rate as a Benchmark Interest Rate for Hedge Accounting Purposes” (“ASU 2018-16”). ASU 2018-16 permits the use of the overnight index swap rate based on the Secured Overnight Financing Rate (“SOFR”) to be used as a U.S. benchmark interest rate for purposes of applying hedge accounting under ASC 815. ASU 2018-16 is effective for the Company, which has already adopted ASU 2017-12, for reporting periods beginning after December 15, 2018 and is required to be adopted on a prospective basis for qualifying new or re-designated hedging relationships entered into on or after the date of adoption. The adoption of ASU 2018-16 will not have a material impact on the Company’s consolidated financial statements.

Consolidation

In October 2018, the FASB issued ASU 2018-17, “Consolidation (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities” (“ASU 2018-17”). ASU 2018-17 is intended to improve the accounting when considering indirect interests held through related parties under common control for determining whether fees paid to decision makers and service providers are variable interests. ASU 2018-17 is effective for the Company for reporting periods beginning after December 15, 2019, with early adoption permitted. The adoption of ASU 2018-17 will not have a material impact on the Company’s consolidated financial statements.

Boston Properties, Inc.

Equity Offering Costs

Underwriting commissions and offering costs have been reflected as a reduction of additional paid-in capital.

Treasury Stock

Boston Properties, Inc.’s share repurchases are reflected as treasury stock utilizing the cost method of accounting and are presented as a reduction to consolidated stockholders’ equity.

Dividends

Earnings and profits, which determine the taxability of dividends to stockholders, will differ from income reported for financial reporting purposes due to the differences for federal income tax purposes in the treatment of gains/losses on the sale of real property, revenue and expense recognition, compensation expense, and in the estimated useful lives and basis used to compute depreciation.

The tax treatment of common dividends per share for federal income tax purposes is as follows:



	For the year ended December 31,
	2019					2018					2017
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	2.99		94.84	%	$	2.79		78.17	%	$	2.86		98.29	%
Capital gain income	0.16			5.16	%	0.78			21.83	%	0.05			1.71	%
Total	$	3.15	(1)	100.00	%	$	3.57	(2)	100.00	%	$	2.91	(3)	100.00	%

_____________


(1)	The fourth quarter 2019 regular quarterly dividend was $0.98 per common share of which approximately $0.04 per common share was allocable to 2019 and approximately $0.94 per common share is allocable to 2020.


(2)	The fourth quarter 2018 regular quarterly dividend was $0.95 per common share of which approximately $0.69 per common share was allocable to 2018 and approximately $0.26 per common share is allocable to 2019.


(3)	The fourth quarter 2017 regular quarterly dividend was $0.80 per common share of which approximately $0.47 per common share was allocable to 2017 and approximately $0.33 per common share is allocable to 2018.

Income Taxes

Boston Properties, Inc. has elected to be treated as a REIT under Sections 856 through 860 of the Code, commencing with its taxable year ended December 31, 1997. As a result, it generally will not be subject to federal corporate income tax on its taxable income that is distributed to its stockholders. A REIT is subject to a number of organizational and operational requirements, including a requirement that it currently distribute at least 90% of its annual taxable income (with certain adjustments). Boston Properties, Inc.’s policy is to distribute at least 100% of its taxable income. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to Boston Properties, Inc.’s consolidated taxable REIT subsidiaries. Boston Properties, Inc.’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. Boston Properties, Inc. has no uncertain tax positions recognized as of December 31, 2019 and 2018.

The Company owns a hotel property that it leases to one of its taxable REIT subsidiaries and that is managed by Marriott International, Inc. The hotel taxable REIT subsidiary, a wholly owned subsidiary of Boston Properties Limited Partnership, is the lessee pursuant to the lease for the hotel property. As lessor, Boston Properties Limited Partnership is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of a management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, Boston Properties, Inc. has recorded a tax provision in its Consolidated Statements of Operations for the years ended December 31, 2019, 2018 and 2017.

Certain entities included in Boston Properties, Inc.’s consolidated financial statements are subject to certain state and local taxes. These taxes are recorded as operating expenses in the accompanying consolidated financial statements.

Boston Properties Limited Partnership

Income Taxes

The partners are required to report their respective share of Boston Properties Limited Partnership’s taxable income or loss on their respective tax returns and are liable for any related taxes thereon. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to Boston Properties Limited Partnership’s consolidated taxable REIT subsidiaries. Boston Properties Limited Partnership’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. Boston Properties Limited Partnership has no uncertain tax positions recognized as of December 31, 2019 and 2018.

The Company owns a hotel property which is managed through a taxable REIT subsidiary. The hotel taxable REIT subsidiary, a wholly owned subsidiary Boston Properties Limited Partnership, is the lessee pursuant to the lease for the hotel property. As lessor, Boston Properties Limited Partnership is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of a management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, Boston Properties Limited Partnership has recorded a tax provision in its Consolidated Statements of Operations for the years ended December 31, 2019, 2018 and 2017.

Certain entities included in Boston Properties Limited Partnership’s consolidated financial statements are subject to certain state and local taxes. These taxes are recorded as operating expenses in the accompanying consolidated financial statements.

Real Estate

9 Months Ended

Sep. 30, 2019

Real Estate [Abstract]

Real Estate

3. Real Estate

Boston Properties, Inc.

Real estate consisted of the following at December 31, 2019 and December 31, 2018 (in thousands):



	2019			2018
Land	$	5,111,606		$	5,072,568
Right of use assets - finance leases	237,394			—
Right of use assets - operating leases	148,640			—
Land held for future development (1)	254,828			200,498
Buildings and improvements	13,646,054			13,356,751
Tenant improvements	2,656,439			2,396,932
Furniture, fixtures and equipment	44,313			44,351
Construction in progress	789,736			578,796
Total	22,889,010			21,649,896
Less: Accumulated depreciation	(5,266,798		)	(4,897,777		)
	$	17,622,212		$	16,752,119

_______________


(1)	Includes pre-development costs.

Boston Properties Limited Partnership

Real estate consisted of the following at December 31, 2019 and December 31, 2018 (in thousands):



	2019			2018
Land	$	5,011,153		$	4,971,475
Right of use assets - finance leases	237,394			—
Right of use assets - operating leases	148,640			—
Land held for future development (1)	254,828			200,498
Buildings and improvements	13,351,286			13,059,488
Tenant improvements	2,656,439			2,396,932
Furniture, fixtures and equipment	44,313			44,351
Construction in progress	789,736			578,796
Total	22,493,789			21,251,540
Less: Accumulated depreciation	(5,162,908		)	(4,800,475		)
	$	17,330,881		$	16,451,065

_______________


(1)	Includes pre-development costs.

Developments/Redevelopments

On May 9, 2019, the Company entered into a 15-year lease with Google, LLC for approximately 379,000 net rentable square feet of Class A office space in a build-to-suit development project located at the Company’s 325 Main Street property at Kendall Center in Cambridge, Massachusetts. 325 Main Street consisted of an approximately 115,000 net rentable square foot Class A office property that was demolished and is being developed into an approximately 420,000 net rentable square foot Class A office property, including approximately 41,000 net rentable square feet of retail space. On May 9, 2019, the Company commenced development of the project. Boston Properties, Inc. and Boston Properties Limited Partnership recognized approximately $9.9 million and $9.5 million, respectively, of depreciation expense associated with the acceleration of depreciation on the assets being removed from service and demolished as part of the redevelopment of the property.

On June 1, 2019, the Company partially placed in-service 20 CityPoint, a Class A office project with approximately 211,000 net rentable square feet located in Waltham, Massachusetts.

On September 30, 2019, the Company commenced the redevelopment of 200 West Street, a Class A office project with approximately 261,000 net rentable square feet located in Waltham, Massachusetts. The redevelopment is a conversion of a 126,000 square foot portion of the property to laboratory space.

On October 24, 2019, the Company completed and placed in-service 145 Broadway, a build-to-suit Class A office project with approximately 483,000 net rentable square feet located in Cambridge, Massachusetts.

Ground Leases

On January 24, 2019, the ground lessor under the Company’s 65-year ground lease for land totaling approximately 5.6 acres at Platform 16 located in San Jose, California made available for lease to the Company the remaining land parcels. As a result, the Company recognized the remaining portion of the right of use finance lease asset and finance lease liability. The Company entered into the ground lease in 2018, however, at the inception of the ground lease only a portion of the land was available for lease from the lessor, resulting in the Company recognizing only a portion of the ground lease. In the aggregate, the land will support the development of approximately 1.1 million square feet of commercial office space. The ground lease provides the Company with the right to purchase all of the land during a 12-month period commencing February 1, 2020 at a purchase price of approximately $134.8 million. The Company was reasonably certain it would exercise the option to purchase the land and as a result, the Company concluded that the lease should be accounted for as a finance lease. As a result, the Company recorded an approximately $122.6 million right of use asset - finance lease and a lease liability - finance lease on the Company’s Consolidated Balance Sheets reflecting the remaining land parcels made available for lease to the Company. Finance lease assets and liabilities are accounted for at the lower of fair market value or the present value of future lease payments. For land leases classified as finance leases because of a purchase option that the Company views as an economic incentive, the Company follows its existing policy and does not depreciate land because it is assumed to have an indefinite life. See also “Dispositions” below and Notes 5 and 19.

As of January 24, 2019, the lease payments from the finance lease related to the remaining parcels made available for lease to the Company were as follows (in thousands):



Period from January 24, 2019 through December 31, 2019	$	17,918
2020	109,460
Total expected minimum lease payments	127,378
Interest portion	(4,815		)
Present value of expected net lease payments	$	122,563

On July 16, 2019, the Company executed a 75-year ground lease with The George Washington University for land parcels at 2100 Pennsylvania Avenue located in Washington, DC and commenced development of an approximately 470,000 net rentable square foot Class A office property pursuant to a development agreement that the Company entered into with The George Washington University in 2016. The development agreement provided for the execution of the ground lease upon completion of the entitlement process and relocation of existing tenants. Also in 2016, the Company made a deposit of $15.0 million that, upon execution of the ground lease, is credited against ground rent payable under the ground lease. The present value of the lease payments exceeds substantially all of the fair value of the underlying asset and as a result, the Company has concluded that the ground lease should be accounted for as a finance lease. As a result, the Company recorded an approximately $185.1 million right of use asset - finance lease and an approximately $165.0 million lease liability - finance lease on the Company’s Consolidated Balance Sheets. The difference between the right of use asset - finance lease and lease liability - finance lease is the $15.0 million deposit that was made in 2016 and approximately $5.1 million of initial direct costs. Although the finance lease is for land only, as this was not classified as a finance lease because of a purchase option, the right of use asset will be amortized over the shorter of the useful life of the asset or the lease term. As land is assumed to have an indefinite life, the right of use asset - finance lease will be amortized on a straight-line basis over the 75-year term. In 2017, the Company entered into a 16-year lease with a tenant for approximately 300,000 net rentable square feet of space at the property.

As of July 16, 2019, the lease payments from the finance lease were as follows (in thousands):



Period from July 16, 2019 through December 31, 2019	$	—
2020	—
2021	3,863
2022	8,576
2023	8,669
Thereafter	1,358,518
Total expected minimum lease payments	1,379,626
Interest portion	(1,214,649		)
Present value of expected net lease payments	$	164,977

Acquisitions

On January 10, 2019, the Company acquired land parcels at its Carnegie Center property located in Princeton, New Jersey for a gross purchase price of approximately $51.5 million, which includes an aggregate of approximately $8.6 million of additional amounts that are payable in the future to the seller upon the development or sale of each of the parcels. The land parcels could support approximately 1.7 million square feet of development.

On August 27, 2019, the Company acquired 880 and 890 Winter Street located in Waltham, Massachusetts for a gross purchase price of approximately $106.0 million in cash. 880 and 890 Winter Street consists of two Class A office properties aggregating approximately 392,000 net rentable square feet. The following table summarizes the allocation of the purchase price, including transaction costs, of 880 and 890 Winter Street at the date of acquisition (in thousands):



Land	$	29,510
Building and improvements	59,788
Tenant improvements	6,024
In-place lease intangibles	11,494
Above-market lease intangibles	246
Below-market lease intangibles	(1,092		)
Net assets acquired	$	105,970

The following table summarizes the estimated annual amortization of the acquired in-place lease intangibles, the acquired above-market lease intangibles and the acquired below-market lease intangibles for 880 and 890 Winter Street for the remainder of 2019 and each of the next five succeeding fiscal years (in thousands):



	Acquired In-Place Lease Intangibles		Acquired Above-Market Lease Intangibles		Acquired Below- Market Lease Intangibles
Period from August 27, 2019 through December 31, 2019	$	1,801	$	28	$	(226	)
2020	4,485		80		(599		)
2021	2,391		80		(237		)
2022	1,121		43		(30		)
2023	179		15		—
2024	60		—		—

880 and 890 Winter Street contributed approximately $4.9 million of revenue and approximately ($0.6) million of earnings to the Company for the period from August 27, 2019 through December 31, 2019.

Dispositions

On January 24, 2019, the Company completed the sale of its 2600 Tower Oaks Boulevard property located in Rockville, Maryland for a gross sale price of approximately $22.7 million. Net cash proceeds totaled approximately $21.4 million, resulting in a loss on sale of real estate totaling approximately $0.6 million. The Company recognized an impairment loss totaling approximately $3.1 million for Boston Properties, Inc. and approximately $1.5 million for Boston Properties Limited Partnership during the year ended December 31, 2018. 2600 Tower Oaks Boulevard is an approximately 179,000 net rentable square foot Class A office property. 2600 Tower Oaks contributed approximately $(0.2) million of net loss to the Company for the period from January 1, 2019 through January 23, 2019 and contributed approximately $(0.6) million and $(0.1) million of net loss to the Company for the years ended December 31, 2018 and 2017, respectively.

At March 31, 2019, the Company evaluated the expected hold period of its One Tower Center property located in East Brunswick, New Jersey and, based on a shorter-than-expected hold period, the Company reduced the carrying value of the property to its estimated fair value at March 31, 2019 and recognized an impairment loss totaling approximately $24.0 million for Boston Properties, Inc. and approximately $22.3 million for Boston Properties Limited Partnership. The Company’s estimated fair value was based on a pending offer from a third party to acquire the property and the subsequent execution of a purchase and sale agreement on April 18, 2019 for a gross sale price of $38.0 million. On June 3, 2019, the Company completed the sale of the property. Net cash proceeds totaled approximately $36.6 million, resulting in a loss on sale of real estate totaling approximately $0.8 million. One Tower Center is an approximately 410,000 net rentable square foot Class A office property. One Tower Center contributed approximately $(0.9) million of net loss to the Company for the period from January 1, 2019 through June 2, 2019 and contributed approximately $(2.7) million and $(3.5) million of net loss to the Company for the years ended December 31, 2018 and 2017, respectively.

On June 28, 2019, the Company completed the sale of its 164 Lexington Road property located in Billerica, Massachusetts for a gross sale price of $4.0 million. Net cash proceeds totaled approximately $3.8 million, resulting in a gain on sale of real estate totaling approximately $2.5 million for Boston Properties, Inc. and approximately $2.6 million for Boston Properties Limited Partnership. 164 Lexington Road is an approximately 64,000 net rentable square foot Class A office property. 164 Lexington Road contributed approximately $(0.1) million of net loss to the Company for the period from January 1, 2019 through June 27, 2019 and contributed approximately $(0.2) million and $(0.2) million of net loss to the Company for the years ended December 31, 2018 and 2017, respectively.

On September 20, 2019, the Company entered into a joint venture with Canada Pension Plan Investment Board (“CPPIB”) to develop Platform 16 located in San Jose, California. Platform 16 consists of a 65-year ground lease for land totaling approximately 5.6 acres that will support the development of approximately 1.1 million square feet of commercial office space. During 2018, the Company entered into the ground lease, which provides for the right to purchase all of the land during a 12-month period commencing February 1, 2020 at a purchase price of approximately $134.8 million. The Company contributed the ground lease interest and improvements totaling approximately $28.2 million for its initial 55% interest in the joint venture. CPPIB contributed cash totaling approximately $23.1 million for its initial 45% interest in the joint venture. Upon the CPPIB contribution, the Company ceased accounting for the joint venture entity on a consolidated basis and is accounting for the joint venture entity on an unconsolidated basis using the equity method of accounting, as it has reduced its ownership interest and no longer has a controlling financial or operating interest in the joint venture entity (See Note 5). The Company did not recognize a gain on the retained or sold interest in the real estate contributed to the joint venture, as the fair value of the real estate approximated its carrying value.

On December 20, 2019, the Company completed the sale of the remaining parcel of land at its Washingtonian North property located in Gaithersburg, Maryland for a gross sale price of approximately $7.8 million. Net cash proceeds totaled approximately $7.3 million, resulting in a loss on sale of real estate totaling approximately $0.1 million. The Company recognized an impairment loss totaling approximately $1.8 million during the year ended December 31, 2016.

Deferred Charges

12 Months Ended

Dec. 31, 2019

Deferred Charges [Abstract]

Deferred Charges

4. Deferred Charges

Deferred charges consisted of the following at December 31, 2019 and December 31, 2018 (in thousands):



	2019			2018
Leasing costs, including lease related intangibles	$	1,155,958		$	1,191,297
Financing costs	12,728			12,796
	1,168,686			1,204,093
Less: Accumulated amortization	(479,473		)	(525,369		)
	$	689,213		$	678,724

The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands).



	Acquired In-Place Lease Intangibles
2020	$	17,536
2021	11,001
2022	5,918
2023	4,286
2024	2,510

Investments in Unconsolidated Joint Ventures

12 Months Ended

Dec. 31, 2019

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures

5. Investments in Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at December 31, 2019 and 2018:



					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			December 31, 2019			December 31, 2018
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.0	%		$	(4,872	)	$	(6,424	)
BP/CRF Metropolitan Square, LLC	Metropolitan Square	20.0	%		9,134			2,644
901 New York, LLC	901 New York Avenue	25.0	%	(2)	(12,113		)	(13,640		)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.3	%	(3)	36,789			38,214
Annapolis Junction NFM LLC	Annapolis Junction	50.0	%	(4)	25,391			25,268
540 Madison Venture LLC	540 Madison Avenue	60.0	%	(5)	2,953			66,391
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.0	%		(5,439		)	(5,026		)
501 K Street LLC	1001 6th Street	50.0	%	(6)	42,496			42,557
Podium Developer LLC	The Hub on Causeway - Podium	50.0	%		49,466			69,302
Residential Tower Developer LLC	Hub50House	50.0	%		55,092			47,505
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.0	%		9,883			3,022
Office Tower Developer LLC	100 Causeway Street	50.0	%		56,606			23,804
1265 Main Office JV LLC	1265 Main Street	50.0	%		3,780			3,918
BNY Tower Holdings LLC	Dock 72	50.0	%		94,804			82,520
BNYTA Amenity Operator LLC	Dock 72	50.0	%		—			N/A
CA-Colorado Center Limited Partnership	Colorado Center	50.0	%		252,069			253,495
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.0	%		56,247			69,724
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.0	%		67,499			46,993
SMBP Venture LP	Santa Monica Business Park	55.0	%		163,937			180,952
Platform 16 Holdings LP	Platform 16	55.0	%	(7)	29,501			N/A
					$	933,223		$	931,219

_______________


(1)	Investments with deficit balances aggregating approximately $22.4 million and $25.1 million at December 31, 2019 and 2018, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.


(2)	The Company’s economic ownership has increased based on the achievement of certain return thresholds.


(3)	The Company’s wholly-owned subsidiary that owns Wisconsin Place Office also owns a 33.3% interest in the joint venture entity that owns the land, parking garage and infrastructure of the project.


(4)	The joint venture owns three in-service buildings and two undeveloped land parcels.


(5)	The property was sold on June 27, 2019. As of December 31, 2019, the investment is comprised of undistributed cash. See note below for additional details.


(6)	Under the joint venture agreement for this land parcel, the partner will be entitled to up to two additional payments from the venture based on increases in total entitled square footage of the project above 520,000 square feet and achieving certain project returns at stabilization.


(7)	This entity is a VIE (See Note 1).

Certain of the Company’s unconsolidated joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of its interest in the joint ventures. With limited exceptions under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners. Under certain of the Company’s joint venture agreements, if certain return thresholds are achieved the partners or the Company will be entitled to an additional promoted interest or payments.

The combined summarized balance sheets of the Company’s unconsolidated joint ventures are as follows:



	December 31, 2019		December 31, 2018
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	3,904,400	$	3,545,906
Other assets	502,706		543,512
Total assets	$	4,407,106	$	4,089,418
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	2,218,853	$	2,017,609
Other liabilities (2)	749,675		582,006
Members’/Partners’ equity	1,438,578		1,489,803
Total liabilities and members’/partners’ equity	$	4,407,106	$	4,089,418
Company’s share of equity	$	591,905	$	622,498
Basis differentials (3)	341,318		308,721
Carrying value of the Company’s investments in unconsolidated joint ventures (4)	$	933,223	$	931,219

_______________


(1)	At December 31, 2019, this amount includes right of use assets - finance leases and right of use assets - operating leases totaling approximately $383.9 million and $12.1 million, respectively.


(2)	At December 31, 2019, this amount includes lease liabilities - finance leases and lease liabilities - operating leases totaling approximately $510.8 million and $17.3 million, respectively.

(3)

This amount represents the aggregate difference between the Company’s historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials result from impairments of investments, acquisitions through joint ventures with no change in control and upon the transfer of assets that were previously owned by the Company into a joint venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level. At December 31, 2019 and 2018, there was an aggregate basis differential of approximately $311.3 million and $316.7 million, respectively, between the carrying value of the Company’s investment in the joint venture that owns Colorado Center and the joint venture’s basis in the assets and liabilities, which differential (excluding land) shall be amortized over the remaining lives of the related assets and liabilities.


(4)	Investments with deficit balances aggregating approximately $22.4 million and $25.1 million at December 31, 2019 and 2018, respectively, have been reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

The combined summarized statements of operations of the Company’s unconsolidated joint ventures are as follows:



	For the year ended December 31,
	2019			2018			2017
	(in thousands)
Total revenue (1)	$	322,817		$	271,951		$	222,517
Expenses
Operating	122,992			106,610			90,542
Transaction costs	1,000			—			—
Depreciation and amortization (2)	102,296			103,079			57,079
Total expenses	226,288			209,689			147,621
Other income (expense)
Gains on sales of real estate (3)	32,706			16,951			—
Interest expense	(84,409		)	(71,308		)	(46,371		)
Net income	$	44,826		$	7,905		$	28,525

Company’s share of net income	$	24,423		$	8,084		$	18,439
Basis differential (3)(4)	22,169			(5,862		)	(7,207		)
Income from unconsolidated joint ventures	$	46,592		$	2,222		$	11,232

_______________


(1)	Includes straight-line rent adjustments of approximately $32.4 million, $15.9 million and $21.7 million for the years ended December 31, 2019, 2018 and 2017, respectively.


(2)	During the year ended December 31, 2018, the joint venture that owns Metropolitan Square in Washington, DC, commenced a renovation project and recorded accelerated depreciation expense of approximately $22.4 million related to the remaining book value of the assets to be replaced. The Company’s share of the accelerated depreciation expense totaled approximately $4.5 million.

(3)

For the year ended December 31, 2019, represents the gain on sale of 540 Madison Avenue recognized by the joint venture, as described below. During 2008, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture resulting in a basis differential between the carrying value of the Company’s investment in the joint venture and the joint venture’s basis in the assets and liabilities of the property. As a result of the historical basis difference, the Company recognized a gain on sale of real estate totaling approximately $47.2 million for the year ended December 31, 2019, which consists of its share of the gain on sale reported by the joint venture as well as an adjustment for the basis differential. The gain on sale of real estate is included in Income from Unconsolidated Joint Ventures in the Company’s Consolidated Statements of Operations.


(4)	Includes straight-line rent adjustments of approximately $2.1 million, $2.4 million and $1.9 million for the years ended December 31, 2019, 2018 and 2017, respectively. Also includes net above-/below-market rent adjustments of approximately $1.7 million, $1.6 million and $2.9 million for the years ended December 31, 2019, 2018 and 2017, respectively.

On January 24, 2019, a joint venture in which the Company has a 50% interest extended the loan collateralized by its Annapolis Junction Building Six property. At the time of the extension, the outstanding balance of the loan totaled approximately $13.0 million and was scheduled to mature on November 17, 2019, with a one-year extension option, subject to certain conditions. The extended loan has a total commitment amount of approximately $14.3 million, bears interest at a variable rate equal to LIBOR plus 2.00% per annum and matures on November 17, 2020. Annapolis Junction Building Six is a Class A office property with approximately 119,000 net rentable square feet located in Annapolis, Maryland.

On April 26, 2019, a joint venture in which the Company has a 50% interest obtained construction financing with a total commitment of $255.0 million collateralized by its 7750 Wisconsin Avenue development project located in Bethesda, Maryland. The construction financing bears interest at a variable rate equal to LIBOR plus 1.25% per annum and matures on April 26, 2023, with two, one-year extension options, subject to certain conditions. As of December 31, 2019, approximately $64.5 million has been drawn under the loan. 7750 Wisconsin Avenue is a 734,000 net rentable square foot build-to-suit Class A office project and below-grade parking garage.

On May 28, 2019, joint ventures in which the Company has a 50% interest and that own The Hub on Causeway - Podium and 100 Causeway Street development projects entered into an infrastructure development assistance agreement (the “IDAA”) with the Commonwealth of Massachusetts and the City of Boston. Per the IDAA, The Hub on Causeway - Podium development project would be reimbursed for certain costs of public infrastructure improvements using the proceeds of up to $30.0 million in aggregate principal amount of municipal bonds issued by the Commonwealth of Massachusetts. On September 16, 2019, the joint venture received the full reimbursement of costs for the public infrastructure improvements totaling approximately $28.8 million, which has been reflected as a reduction to the carrying value of the real estate of The Hub on Causeway - Podium property. The construction loan agreement for The Hub on Causeway - Podium was modified to require the joint venture to pay down the construction loan principal balance using the proceeds received from the reimbursement of costs of the public infrastructure improvements and on September 16, 2019, the joint venture that owns The Hub on Causeway - Podium development project paid down the construction loan principal balance in the amount of approximately $28.8 million. On November 22, 2019, the joint venture that owns The Hub on Causeway - Podium development project completed and fully placed in-service The Hub on Causeway - Podium development project, an approximately 382,000 net rentable square foot project containing retail and office space located in Boston, Massachusetts.

On June 27, 2019, a joint venture in which the Company has a 60% interest completed the sale of 540 Madison Avenue in New York City for a gross sale price of approximately $310.3 million, including the assumption by the buyer of the mortgage loan collateralized by the property totaling $120.0 million. The mortgage loan bore interest at a variable rate equal to LIBOR plus 1.10% per annum and was scheduled to mature on June 5, 2023. Net cash proceeds totaled approximately $178.7 million, of which the Company’s share was approximately $107.1 million, after the payment of transaction costs. During 2008, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture. As a result, the Company recognized a gain on sale of real estate totaling approximately $47.2 million, which is included in Income from Unconsolidated Joint

Ventures in the accompanying Consolidated Statements of Operations. 540 Madison Avenue is an approximately 284,000 net rentable square foot Class A office property.

On September 5, 2019, a joint venture in which the Company has a 50% interest obtained construction financing with a total commitment of $400.0 million collateralized by its 100 Causeway Street development project located in Boston, Massachusetts. The construction financing bears interest at a variable rate equal to LIBOR plus 1.50% per annum (LIBOR plus 1.375% per annum upon stabilization, as defined in the loan agreement) and matures on September 5, 2023, with two, one-year extension options, subject to certain conditions. As of December 31, 2019, approximately $81.1 million has been drawn under the loan. 100 Causeway Street is an approximately 632,000 net rentable square foot Class A office project.

On September 20, 2019, the Company entered into a joint venture with CPPIB to develop Platform 16 located in San Jose, California. Platform 16 consists of a 65-year ground lease for land totaling approximately 5.6 acres that will support the development of approximately 1.1 million square feet of commercial office space (See Note 19). The Company contributed the ground lease interest and improvements totaling approximately $28.2 million for its initial 55% interest in the joint venture (See Note 3). CPPIB contributed cash totaling approximately $23.1 million for its initial 45% interest in the joint venture. The Company will provide customary development, property management and leasing services to the joint venture.

On October 1, 2019, a joint venture in which the Company has a 50% interest partially placed in-service Dock 72, a Class A office project with approximately 670,000 net rentable square feet located in Brooklyn, New York.

On October 1, 2019, a joint venture in which the Company has a 50% interest partially placed in-service Hub50House, an approximately 320,000 square foot project comprised of 440 residential units located in Boston, Massachusetts.

On December 6, 2019, a joint venture in which the Company has a 50% interest extended the mortgage loan collateralized by Annapolis Junction Building Seven and Building Eight. At the time of the extension, the outstanding balance of the loan totaled approximately $34.8 million, bore interest at a variable rate equal to LIBOR plus 2.35% per annum and was scheduled to mature on December 7, 2019, with three, one-year extension options, subject to certain conditions. The extended loan matures on March 6, 2020. Annapolis Junction Building Seven and Building Eight are Class A office properties with approximately 127,000 and 126,000 net rentable square feet, respectively, located in Annapolis, Maryland.

Mortgage Notes Payable, Net

12 Months Ended

Dec. 31, 2019

Loans Payable [Abstract]

Mortgage Notes Payable, Net

6. Mortgage Notes Payable, Net

The Company had outstanding mortgage notes payable totaling approximately $2.9 billion and $3.0 billion as of December 31, 2019 and 2018, respectively, each collateralized by one or more buildings and related land included in real estate assets. The mortgage notes payable are generally due in monthly installments and mature at various dates through June 9, 2027.

Fixed rate mortgage notes payable totaled approximately $2.9 billion and $3.0 billion at December 31, 2019 and 2018, respectively, with contractual interest rates ranging from 3.43% to 6.94% per annum at December 31, 2019 and 3.43% to 7.69% at December 31, 2018 (with a weighted-average interest rate of 3.73% and 3.77% per annum at December 31, 2019 and 2018, respectively). There were no variable rate mortgage loans at December 31, 2019 and 2018.

On December 19, 2019, the Company used available cash to repay the bond financing collateralized by its New Dominion Technology Park, Building One property totaling approximately $26.5 million. The bond financing bore interest at a weighted-average fixed rate of approximately 7.69% per annum and was scheduled to mature on January 15, 2021. The Company recognized a loss from early extinguishment of debt totaling approximately $1.5 million, which amount included the payment of a prepayment penalty totaling approximately $1.4 million. New Dominion Technology Park, Building One is an approximately 235,000 net rentable square foot Class A office property located in Herndon, Virginia (See Note 19).

No mortgage loans at December 31, 2019 and December 31, 2018 had been accounted for at fair value. Prior to December 31, 2017, the Company had mortgage loans that were accounted for at fair value and the impact of recording them at fair value resulted in a decrease to interest expense of approximately $19.6 million for the year ended December 31, 2017.

Contractual aggregate principal payments of mortgage notes payable at December 31, 2019 are as follows (in thousands):



	Principal Payments
2020	$	17,168
2021	17,276
2022	614,710
2023	—
2024	—
Thereafter	2,300,000
Total aggregate principal payments	2,949,154
Deferred financing costs, net	(26,746		)
Total carrying value of mortgage notes payable, net	$	2,922,408

Unsecured Senior Notes

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Unsecured Senior Notes

7. Unsecured Senior Notes

The following summarizes the unsecured senior notes outstanding as of December 31, 2019 (dollars in thousands):



	Coupon/ Stated Rate		Effective Rate(1)		Principal Amount			Maturity Date(2)
10 Year Unsecured Senior Notes	4.125	%	4.289	%	$	850,000		May 15, 2021
11 Year Unsecured Senior Notes	3.850	%	3.954	%	1,000,000			February 1, 2023
10.5 Year Unsecured Senior Notes	3.125	%	3.279	%	500,000			September 1, 2023
10.5 Year Unsecured Senior Notes	3.800	%	3.916	%	700,000			February 1, 2024
7 Year Unsecured Senior Notes	3.200	%	3.350	%	850,000			January 15, 2025
10 Year Unsecured Senior Notes	3.650	%	3.766	%	1,000,000			February 1, 2026
10 Year Unsecured Senior Notes	2.750	%	3.495	%	1,000,000			October 1, 2026
10 Year Unsecured Senior Notes	4.500	%	4.628	%	1,000,000			December 1, 2028
10 Year Unsecured Senior Notes	3.400	%	3.505	%	850,000			June 21, 2029
10.5 Year Unsecured Senior Notes	2.900	%	2.984	%	700,000			March 15, 2030
Total principal					8,450,000
Net unamortized discount					(17,451		)
Deferred financing costs, net					(42,090		)
Total					$	8,390,459

_______________


(1)	Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.


(2)	No principal amounts are due prior to maturity.

On June 21, 2019, Boston Properties Limited Partnership completed a public offering of $850.0 million in aggregate principal amount of its 3.400% unsecured senior notes due 2029. The notes were priced at 99.815% of the principal amount to yield an effective rate (including financing fees) of approximately 3.505% per annum to maturity. The notes will mature on June 21, 2029, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $841.4 million after deducting underwriting discounts and transaction expenses.

On September 3, 2019, Boston Properties Limited Partnership completed a public offering of $700.0 million in aggregate principal amount of its 2.900% unsecured senior notes due 2030. The notes were priced at 99.954% of the principal amount to yield an effective rate (including financing fees) of approximately 2.984% per annum to maturity. The notes will mature on March 15, 2030, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $693.8 million after deducting underwriting discounts and transaction expenses.

On September 18, 2019, Boston Properties Limited Partnership completed the redemption of $700.0 million in aggregate principal amount of its 5.625% senior notes due November 15, 2020. The redemption price was approximately $740.7 million. The redemption price included approximately $13.5 million of accrued and unpaid interest to, but not including, the redemption date. Excluding the accrued and unpaid interest, the redemption price was approximately 103.90% of the principal amount being redeemed. The Company recognized a loss from early extinguishment of debt totaling approximately $28.0 million, which amount included the payment of the redemption premium totaling approximately $27.3 million.

The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60%, (2) a secured debt leverage ratio not to exceed 50%, (3) an interest coverage ratio of greater than 1.50, and (4) an unencumbered asset value of not less than 150% of unsecured debt. At December 31, 2019, Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.

Unsecured Credit Facility	12 Months Ended
Unsecured Credit Facility	Dec. 31, 2019
Line of Credit Facility [Abstract]
Unsecured Credit Facility [Text Block]	8. Unsecured Credit Facility On April 24, 2017, Boston Properties Limited Partnership amended and restated its unsecured revolving credit agreement (as amended and restated, the “2017 Credit Facility”). Among other things, the 2017 Credit Facility (1) increased the total commitment of the revolving line of credit (the “Revolving Facility”) from $1.0 billion to $1.5 billion, (2) extended the maturity date from July 26, 2018 to April 24, 2022, (3) reduced the per annum variable interest rates, and (4) added a $500.0 million delayed draw term loan facility (the “Delayed Draw Facility”) that permitted Boston Properties Limited Partnership to draw upon it provided that amounts drawn and subsequently repaid may not be borrowed again. In addition, Boston Properties Limited Partnership may increase the total commitment under the 2017 Credit Facility by up to $500.0 million through increases in the Revolving Facility or the Delayed Draw Facility, or both, subject to syndication of the increase and other conditions. On April 24, 2018, Boston Properties Limited Partnership exercised its option to draw $500.0 million on its Delayed Draw Facility. The Delayed Draw Facility bears interest at a variable rate equal to LIBOR plus 0.90% per annum based on Boston Properties Limited Partnership’s current credit rating and matures on April 24, 2022. At Boston Properties Limited Partnership’s option, loans under the Revolving Facility and Delayed Draw Facility will bear interest at a rate per annum equal to (1) (a) in the case of loans denominated in Dollars, Euro or Sterling, LIBOR, and (b) in the case of loans denominated in Canadian Dollars, CDOR, in each case, plus a margin ranging from 77.5 to 155 basis points for the Revolving Commitment and 85 to 175 basis points for the Delayed Draw Facility, based on Boston Properties Limited Partnership’s credit rating or (2) an alternate base rate equal to the greatest of (x) the Administrative Agent’s prime rate, (y) the Federal Funds rate plus 0.50% or (z) LIBOR for a one-month period plus 1.00%, in each case, plus a margin ranging from 0 to 55 basis points for the Revolving Facility and 0 to 75 basis points for the Delayed Draw Facility, based on Boston Properties Limited Partnership’s credit rating. The 2017 Credit Facility also contains a competitive bid option for up to 65% of the Revolving Facility that allows banks that are part of the lender consortium to bid to make loan advances to Boston Properties Limited Partnership at a reduced interest rate. In addition, Boston Properties Limited Partnership is obligated to pay (1) in quarterly installments a facility fee on the total commitment under the Revolving Facility at a rate per annum ranging from 0.10% to 0.30% based on Boston Properties Limited Partnership’s credit rating, (2) an annual fee on the undrawn amount of each letter of credit equal to the LIBOR margin on the Revolving Facility and (3) a fee on the unused commitments under the Delayed Draw Facility equal to 0.15% per annum. Based on Boston Properties Limited Partnership’s December 31, 2019 credit rating, (1) the applicable Eurocurrency margins for the Revolving Facility and Delayed Draw Facility are 0.825% and 0.90%, respectively, (2) the alternate base rate margin is zero basis points for each of the Revolving Facility and Delayed Draw Facility and (3) the facility fee on the Revolving Facility commitment is 0.125% per annum. At December 31, 2019 and 2018, Boston Properties Limited Partnership had $500.0 million of borrowings outstanding under its Delayed Draw Facility and no amounts outstanding under its Revolving Facility. The 2017 Credit Facility contains customary representations and warranties, affirmative and negative covenants and events of default provisions, including failure to pay indebtedness, breaches of covenants, and bankruptcy and other insolvency events, which could result in the acceleration of all amounts and cancellation of all commitments outstanding under the Credit Agreement. Among other covenants, the 2017 Credit Facility requires that Boston Properties Limited Partnership maintain on an ongoing basis: (1) a leverage ratio not to exceed 60%, however, the leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (2) a secured debt leverage ratio not to exceed 55%, (3) a fixed charge coverage ratio of at least 1.40, (4) an unsecured debt leverage ratio not to exceed 60%, however, the unsecured debt leverage ratio may increase to no greater than 65% provided that it is reduced to 60% within one year, (5) an unsecured debt interest coverage ratio of at least 1.75 and (6) limitations on permitted investments. At December 31, 2019, Boston Properties Limited Partnership was in compliance with each of these financial and other covenant requirements.

Commitments And Contingencies	12 Months Ended
Commitments And Contingencies	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	9. Commitments and Contingencies General In the normal course of business, the Company guarantees its performance of services or indemnifies third parties against its negligence. In addition, in the normal course of business, the Company guarantees to certain tenants the obligations of its subsidiaries for the payment of tenant improvement allowances and brokerage commissions in connection with their leases and limited costs arising from delays in delivery of their premises. The Company has letter of credit and performance obligations related to lender and development requirements that total approximately $21.0 million. Certain of the Company’s joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of its interest in the joint ventures. With limited exception, under these provisions, the Company is not compelled to purchase the interest of its outside joint venture partners. From time to time, under certain of the Company’s joint venture agreements, if certain return thresholds are achieved, either the Company or its partners may be entitled to an additional promoted interest or payments. See also Note 10. From time to time, the Company (or ventures in which the Company has an ownership interest) has agreed, and may in the future agree, to (1) guarantee portions of the principal, interest and other amounts in connection with their borrowings, (2) provide customary environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, misrepresentation and bankruptcy) in connection with their borrowings and (3) provide guarantees to lenders, tenants and other third parties for the completion of development projects. The Company has agreements with its outside partners whereby the partners agree to reimburse the joint venture for their share of any payments made under the guarantee. In some cases, the Company earns a fee from the applicable joint venture for providing the guarantee. In connection with the refinancing of 767 Fifth Avenue’s (the General Motors Building) secured loan by the Company’s consolidated joint venture entity, 767 Venture, LLC, the Company guaranteed the consolidated entity’s obligation to fund various reserves for tenant improvement costs and allowances, leasing commissions and free rent obligations in lieu of cash deposits. As of December 31, 2019, the maximum funding obligation under the guarantee was approximately $70.2 million. The Company earns a fee from the joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee. As of December 31, 2019, no amounts related to the guarantee are recorded as liabilities in the Company’s consolidated financial statements. Pursuant to the lease agreement with Marriott, the Company has guaranteed the completion of the office building and parking garage on behalf of its 7750 Wisconsin Avenue joint venture and has also agreed to provide any financing guaranty that may be required with respect to third-party construction financing. The Company earns fees from the joint venture for providing the guarantees and any amounts the Company pays under the guarantee(s) will be deemed to be capital contributions by the Company to the joint venture. The Company has also agreed to fund construction costs through capital contributions to the joint venture in the event of unavailability or insufficiency of third-party construction financing. In addition, the Company has guaranteed to Marriott, as hotel manager, the completion of a hotel being developed by an affiliate of The Bernstein Companies (the Company’s partner in the 7750 Wisconsin Avenue joint venture) adjacent to the office property, for which the Company earns a fee from the affiliate of The Bernstein Companies. In addition, the Company entered into agreements with affiliates of The Bernstein Companies whereby the Company could be required to act as a mezzanine and/or mortgage lender and finance the construction of the hotel property. To secure such financing arrangements, affiliates of The Bernstein Companies are required to provide certain security, which varies depending on the specific loan, by pledges of their equity interest in the office property, a fee mortgage on the hotel property, or both. As of December 31, 2019, no amounts related to the contingent aspect of any of the guarantees are recorded as liabilities in the Company’s consolidated financial statements. In connection with the sale and development of the Company’s 6595 Springfield Center Drive development project, the Company has guaranteed the completion of the project and the payment of certain cost overruns in accordance with the development management agreement with the buyer. Although the project has been sold and the lease with the Federal Government tenant has been assigned to the buyer, pursuant to the terms of the Federal Government lease, the Federal Government tenant is not obligated to release the prior owner/landlord from such landlord’s obligations under the lease until completion of the construction. As a result, the entity which previously owned the land remains liable to the Federal Government tenant for the completion of the construction obligations under the lease. The buyer is obligated to fund the balance of the costs to meet such construction obligations, subject to the Company’s obligation to fund cost overruns (if any), as noted above. An affiliate of the buyer has provided a guaranty of the obligations of the buyer to fund such construction costs and the buyer has agreed to use commercially reasonable efforts to require the construction lender to provide certain remedies to the Company in the event the buyer does not fund such construction obligations. As of December 31, 2019, no amounts related to the contingent aspect of the guarantee are recorded as a liability in the Company’s consolidated financial statements (See Note 3). In connection with the redevelopment of the Company’s 325 Main Street property located in Cambridge, Massachusetts, the Company is required, pursuant to the local zoning ordinance, to commence construction of a residential building of at least 200,000 square feet with 25% of the project designated as income-restricted (with a minimum of 20% of the square footage devoted to home ownership units) prior to the occupancy of the 325 Main Street property. 325 Main Street consisted of an approximately 115,000 net rentable square foot Class A office property that was demolished and is being developed into an approximately 420,000 net rentable square foot Class A office property, including approximately 41,000 net rentable square feet of retail space (See Note 3). In 2009, the Company filed a general unsecured creditor’s claim against Lehman Brothers, Inc. for approximately $45.3 million related to its rejection of a lease at 399 Park Avenue in New York City. On January 10, 2014, the trustee for the liquidation of the business of Lehman Brothers allowed the Company’s claim in the amount of approximately $45.2 million. During the years 2014 through 2018, the Company received distributions aggregating approximately $18.0 million, leaving a remaining claim of approximately $27.2 million. The Company will continue to evaluate whether to attempt to sell the remaining claim or wait until the trustee distributes proceeds from the Lehman Brothers estate. Given the inherent uncertainties in bankruptcy proceedings, there can be no assurance as to the timing or amount of additional proceeds, if any, that the Company may ultimately realize on the remaining claim, whether by sale to a third party or by one or more distributions from the trustee. Accordingly, the Company has not recorded any estimated recoveries associated with this gain contingency within its Consolidated Financial Statements at December 31, 2019. Concentrations of Credit Risk Management of the Company performs ongoing credit evaluations of tenants and may require tenants to provide some form of credit support such as corporate guarantees and/or other financial guarantees. Although the Company’s properties are geographically diverse and the tenants operate in a variety of industries, to the extent the Company has a significant concentration of rental revenue from any single tenant, the inability of that tenant to make its lease payments could have an adverse effect on the Company. Insurance The Company’s property insurance program per occurrence limits are $1.0 billion for its portfolio insurance program, including coverage for acts of terrorism other than nuclear, biological, chemical or radiological terrorism (“Terrorism Coverage”). The Company also carries $250 million of Terrorism Coverage for 601 Lexington Avenue, New York, New York (“601 Lexington Avenue”) in excess of the $1.0 billion of coverage in the Company’s property insurance program. Certain properties, including the General Motors Building located at 767 Fifth Avenue in New York, New York (“767 Fifth Avenue”), are currently insured in separate insurance programs. The property insurance program per occurrence limits for 767 Fifth Avenue are $1.625 billion, including Terrorism Coverage. The Company also currently carries nuclear, biological, chemical and radiological terrorism insurance coverage for acts of terrorism certified under the Federal Terrorism Risk Insurance Act (as amended, “TRIA”) (“NBCR Coverage”), which is provided by IXP as a direct insurer, for the properties in the Company’s portfolio, including 767 Fifth Avenue, but excluding certain other properties owned in joint ventures with third parties or which the Company manages. The per occurrence limit for NBCR Coverage is $1.0 billion. Under TRIA, after the payment of the required deductible and coinsurance, the NBCR Coverage provided by IXP is backstopped by the Federal Government if the aggregate industry insured losses resulting from a certified act of terrorism exceed a “program trigger.” In 2019, the program trigger was $180 million and the coinsurance was 19%, however, both will increase in subsequent years pursuant to TRIA. If the Federal Government pays out for a loss under TRIA, it is mandatory that the Federal Government recoup the full amount of the loss from insurers offering TRIA coverage after the payment of the loss pursuant to a formula in TRIA. The Company may elect to terminate the NBCR Coverage if the Federal Government seeks recoupment for losses paid under TRIA, if TRIA is not extended after its expiration on December 31, 2027, if there is a change in its portfolio or for any other reason. The Company intends to continue to monitor the scope, nature and cost of available terrorism insurance. The Company also currently carries earthquake insurance on its properties located in areas known to be subject to earthquakes. In addition, this insurance is subject to a deductible in the amount of 3% of the value of the affected property. Specifically, the Company currently carries earthquake insurance which covers its San Francisco and Los Angeles regions with a $240 million per occurrence limit, and a $240 million annual aggregate limit, $20 million of which is provided by IXP, as a direct insurer. The amount of the Company’s earthquake insurance coverage may not be sufficient to cover losses from earthquakes. In addition, the amount of earthquake coverage could impact the Company’s ability to finance properties subject to earthquake risk. The Company may discontinue earthquake insurance or change the structure of its earthquake insurance program on some or all of its properties in the future if the premiums exceed the Company’s estimation of the value of the coverage. IXP, a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company’s earthquake insurance coverage for its Greater San Francisco and Los Angeles properties and the Company’s NBCR Coverage. Insofar as the Company owns IXP, it is responsible for its liquidity and capital resources, and the accounts of IXP are part of the Company’s consolidated financial statements. In particular, if a loss occurs which is covered by the Company’s NBCR Coverage but is less than the applicable program trigger under TRIA, IXP would be responsible for the full amount of the loss without any backstop by the Federal Government. IXP would also be responsible for any recoupment charges by the Federal Government in the event losses are paid out and its insurance policy is maintained after the payout by the Federal Government. If the Company experiences a loss and IXP is required to pay under its insurance policy, the Company would ultimately record the loss to the extent of the required payment. Therefore, insurance coverage provided by IXP should not be considered as the equivalent of third-party insurance, but rather as a modified form of self-insurance. In addition, Boston Properties Limited Partnership has issued a guarantee to cover liabilities of IXP in the amount of $20.0 million. The Company continues to monitor the state of the insurance market in general, and the scope and costs of coverage for acts of terrorism and California earthquake risk in particular, but the Company cannot anticipate what coverage will be available on commercially reasonable terms in future policy years. There are other types of losses, such as from wars, for which the Company cannot obtain insurance at all or at a reasonable cost. With respect to such losses and losses from acts of terrorism, earthquakes or other catastrophic events, if the Company experiences a loss that is uninsured or that exceeds policy limits, the Company could lose the capital invested in the damaged properties, as well as the anticipated future revenues from those properties. Depending on the specific circumstances of each affected property, it is possible that the Company could be liable for mortgage indebtedness or other obligations related to the property. Any such loss could materially and adversely affect the Company’s business and financial condition and results of operations. Legal Matters The Company is subject to various legal proceedings and claims that arise in the ordinary course of business. These matters are generally covered by insurance. Management believes that the final outcome of such matters will not have a material adverse effect on the financial position, results of operations or liquidity of the Company. State and Local Tax Matters Because Boston Properties, Inc. is organized and qualifies as a REIT, it is generally not subject to federal income taxes, but is subject to certain state and local taxes. In the normal course of business, certain entities through which the Company owns real estate either have undergone, or are currently undergoing, tax audits. Although the Company believes that it has substantial arguments in favor of its positions in the ongoing audits, in some instances there is no controlling precedent or interpretive guidance on the specific point at issue. Collectively, tax deficiency notices received to date from the jurisdictions conducting the ongoing audits have not been material. However, there can be no assurance that future audits will not occur with increased frequency or that the ultimate result of such audits will not have a material adverse effect on the Company’s results of operations. Environmental Matters It is the Company’s policy to retain independent environmental consultants to conduct or update Phase I environmental assessments (which generally do not involve invasive techniques such as soil or ground water sampling) and asbestos surveys in connection with the Company’s acquisition of properties. These pre-purchase environmental assessments have not revealed environmental conditions that the Company believes will have a material adverse effect on its business, assets, financial condition, results of operations or liquidity, and the Company is not otherwise aware of environmental conditions with respect to its properties that the Company believes would have such a material adverse effect. However, from time to time environmental conditions at the Company’s properties have required and may in the future require environmental testing and/or regulatory filings, as well as remedial action. In February 1999, the Company (through a joint venture) acquired from Exxon Corporation a property in Massachusetts that was formerly used as a petroleum bulk storage and distribution facility and was known by the state regulatory authority to contain soil and groundwater contamination. The Company developed an office park on the property. The Company engaged a specially licensed environmental consultant to oversee the management of contaminated soil and groundwater that was disturbed in the course of construction. Under the property acquisition agreement, Exxon agreed to (1) bear the liability arising from releases or discharges of oil and hazardous substances which occurred at the site prior to the Company’s ownership, (2) continue monitoring and/or remediating such releases and discharges as necessary and appropriate to comply with applicable requirements, and (3) indemnify the Company for certain losses arising from preexisting site conditions. Any indemnity claim may be subject to various defenses, and there can be no assurance that the amounts paid under the indemnity, if any, would be sufficient to cover the liabilities arising from any such releases and discharges. Environmental investigations at some of the Company’s properties and certain properties owned by affiliates of the Company have identified groundwater contamination migrating from off-site source properties. In each case the Company engaged a licensed environmental consultant to perform the necessary investigations and assessments and to prepare any required submittals to the regulatory authorities. In each case the environmental consultant concluded that the properties qualify under the regulatory program or the regulatory practice for a status which eliminates certain deadlines for conducting response actions at a site. The Company also believes that these properties qualify for liability relief under certain statutory provisions or regulatory practices regarding upgradient releases. Although the Company believes that the current or former owners of the upgradient source properties may bear responsibility for some or all of the costs of addressing the identified groundwater contamination, the Company will take such further response actions (if any) that it deems necessary or advisable. Other than periodic testing at some of these properties, no such additional response actions are anticipated at this time. Some of the Company’s properties and certain properties owned by the Company’s affiliates are located in urban, industrial and other previously developed areas where fill or current or historical uses of the areas have caused site contamination. Accordingly, it is sometimes necessary to institute special soil and/or groundwater handling procedures and/or include particular building design features in connection with development, construction and other property operations in order to achieve regulatory closure and/or ensure that contaminated materials are addressed in an appropriate manner. In these situations, it is the Company’s practice to investigate the nature and extent of detected contamination, including potential issues associated with contaminant migration, assess potential liability risks and estimate the costs of required response actions and special handling procedures. The Company then uses this information as part of its decision-making process with respect to the acquisition, deal structure and/or development of the property. For example, the Company owns a parcel in Massachusetts which was formerly used as a quarry/asphalt batching facility. Pre-purchase testing indicated that the site contained relatively low levels of certain contaminants. The Company has developed an office park on this property. Prior to and during redevelopment activities, the Company engaged a specially licensed environmental consultant to monitor environmental conditions at the site and prepare necessary regulatory submittals based on the results of an environmental risk characterization. A submittal has been made to the regulatory authorities in order to achieve regulatory closure at this site. The submittal included an environmental deed restriction that mandates compliance with certain protective measures in a portion of the site where low levels of residual soil contamination have been left in place in accordance with applicable laws. The Company expects that resolution of the environmental matters relating to the above will not have a material impact on its business, assets, financial condition, results of operations or liquidity. However, the Company cannot assure you that it has identified all environmental liabilities at its properties, that all necessary remediation actions have been or will be undertaken at the Company’s properties or that the Company will be indemnified, in full or at all, in the event that such environmental liabilities arise.

Noncontrolling Interests

12 Months Ended

Dec. 31, 2019

Noncontrolling Interest [Abstract]

Noncontrolling Interests

10. Noncontrolling Interests

Noncontrolling interests relate to the interests in Boston Properties Limited Partnership not owned by Boston Properties, Inc. and interests in consolidated property partnerships not wholly-owned by the Company. As of December 31, 2019, the noncontrolling interests in Boston Properties Limited Partnership consisted of 16,764,466 OP Units, 1,143,215 LTIP Units (including 118,067 2012 OPP Units, 68,659 2013 MYLTIP Units, 23,100 2014 MYLTIP Units, 28,724 2015 MYLTIP Units and 98,706 2016 MYLTIP Units), 394,921 2017 MYLTIP Units, 336,195 2018 MYLTIP Units and 220,734 2019 MYLTIP Units held by parties other than Boston Properties, Inc.

Noncontrolling Interest—Common Units

During the years ended December 31, 2019 and 2018, 144,481 and 83,136 OP Units, respectively, were presented by the holders for redemption (including 92,678 and 48,389 OP Units, respectively, issued upon conversion of LTIP Units, 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units and 2016 MYLTIP Units) and were redeemed by Boston Properties, Inc. in exchange for an equal number of shares of Common Stock.

At December 31, 2019, Boston Properties Limited Partnership had outstanding 394,921 2017 MYLTIP Units, 336,195 2018 MYLTIP Units and 220,734 2019 MYLTIP Units (See Note 16). Prior to the applicable measurement date (February 6, 2020 for 2017 MYLTIP Units (See Note 19), February 5, 2021 for 2018 MYLTIP Units and February 4, 2022 for 2019 MYLTIP Units), holders of MYLTIP Units will be entitled to receive per unit distributions equal to one-tenth (10%) of the regular quarterly distributions payable on an OP Unit, but will not be entitled to receive any special distributions. After the measurement date, the number of MYLTIP Units, both vested and unvested, that MYLTIP award recipients have earned, if any, based on the establishment of a performance pool, will be entitled to receive distributions in an amount per unit equal to distributions, both regular and special, payable on an OP Unit.

On February 3, 2017, the measurement period for the Company’s 2014 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 27.7% of target or an aggregate of approximately $3.5 million (after giving effect to employee separations and the unallocated reserve). As a result, an aggregate of 447,386 2014 MYLTIP Units that had been previously granted were automatically forfeited.

On February 4, 2018, the measurement period for the Company’s 2015 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 22.0% of target or an aggregate of approximately $3.6 million (after giving effect to employee separations). As a result, an aggregate of 337,847 2015 MYLTIP Units that had been previously granted were automatically forfeited.

On February 9, 2019, the measurement period for the Company’s 2016 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 69.5% of target or an aggregate of approximately $13.6 million (after giving effect to employee separations). As a result, an aggregate of 364,980 2016 MYLTIP Units that had been previously granted were automatically forfeited.

The following table presents Boston Properties Limited Partnership’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units and 2015 MYLTIP Units and, after the February 9, 2019 measurement date, the 2016 MYLTIP Units) and its distributions on the 2016 MYLTIP Units (prior to the February 9, 2019 measurement date), 2017 MYLTIP Units, 2018 MYLTIP Units and 2019 MYLTIP Units (after the February 5, 2019 issuance date) that occurred during the year ended December 31, 2019:



Record Date	Payment Date	Distributions per OP Unit and LTIP Unit		Distributions per MYLTIP Unit
December 31, 2019	January 30, 2020		$0.98		$0.098
September 30, 2019	October 31, 2019		$0.95		$0.095
June 28, 2019	July 31, 2019		$0.95		$0.095
March 29, 2019	April 30, 2019		$0.95		$0.095
December 31, 2018	January 30, 2019		$0.95		$0.095

The following table presents Boston Properties Limited Partnership’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units and, after the February 4, 2018 measurement date, the 2015 MYLTIP Units) and its distributions on the 2015 MYLTIP Units (prior to the February 4, 2018 measurement date), 2016 MYLTIP Units, 2017 MYLTIP Units and 2018 MYLTIP Units (after the February 6, 2018 issuance date) that occurred during the year ended December 31, 2018:



Record Date	Payment Date	Distributions per OP Unit and LTIP Unit		Distributions per MYLTIP Unit
December 31, 2018	January 30, 2019		$0.95		$0.095
September 28, 2018	October 31, 2018		$0.95		$0.095
June 29, 2018	July 31, 2018		$0.80		$0.080
March 29, 2018	April 30, 2018		$0.80		$0.080
December 29, 2017	January 30, 2018		$0.80		$0.080

A holder of an OP Unit may present the OP Unit to Boston Properties Limited Partnership for redemption at any time (subject to restrictions agreed upon at the time of issuance of OP Units to particular holders that may restrict such redemption right for a period of time, generally one year from issuance). Upon presentation of an OP Unit for redemption, Boston Properties Limited Partnership must redeem the OP Unit for cash equal to the then value of a share of common stock of Boston Properties, Inc. Boston Properties, Inc. may, in its sole discretion, elect to assume and satisfy the redemption obligation by paying either cash or issuing one share of Common Stock. The value of the OP Units (not owned by Boston Properties, Inc. and LTIP Units (including the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units) assuming that all conditions had been met for the conversion thereof) had all of such units been redeemed at December 31, 2019 was approximately $2.5 billion based on the last reported price of a share of Common Stock on the New York Stock Exchange of $137.86 per share on December 31, 2019.

Noncontrolling Interests—Property Partnerships

The noncontrolling interests in property partnerships consist of the outside equity interests in ventures that are consolidated with the financial results of the Company because the Company exercises control over the entities that own the properties. The equity interests in these ventures that are not owned by the Company, totaling approximately $1.7 billion at December 31, 2019 and 2018, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.

On May 12, 2016, the partners in the Company’s consolidated entity that owns Salesforce Tower located in San Francisco, California amended the venture agreement. Under the original venture agreement, if the Company elected to fund the construction of Salesforce Tower without a construction loan (or a construction loan of less than 50% of project costs) and the venture commenced vertical construction of the project, then the partner’s capital funding obligation would be limited, in which event the Company would fund up to 2.5% of the total project costs (i.e., 50% of the partner’s 5% interest in the venture) in the form of a loan to the partner. This loan would bear interest at the then prevailing market interest rates for construction loans. Under the amended venture agreement, the partners agreed to structure this funding by the Company as preferred equity rather than a loan. The preferred equity contributed by the Company earned a preferred return equal to LIBOR plus 3.00% per annum and was payable to the Company out of any distributions to which the partner would otherwise be entitled until such preferred equity and preferred return was repaid to the Company. The Company contributed an aggregate of approximately $22.6 million of preferred equity to the venture. Also, under the amended venture agreement, (a) from and after the stabilization date, the partner had the right to cause the Company to purchase all (but not less than all) of the partner’s interest and (b) from and after the third anniversary of the stabilization date, the Company had the right to acquire all (but not less than all) of the partner’s interest, in each case, at an agreed upon purchase price or appraised value. In addition, if certain threshold returns were achieved the partner may be entitled to receive an additional promoted interest with respect to cash flow distributions. The term stabilization date was defined in the agreement to generally mean the first date after completion upon which Salesforce Tower is (1) at least 90% leased and (2) 50% occupied by tenants that are paying rent. Salesforce Tower is an approximately 1,421,000 net rentable square foot Class A office property.

On January 18, 2019, the Company and its partner further amended the venture agreement. Per the amendment, the partner exercised its right to cause the Company to purchase, on April 1, 2019, its 5% ownership interest and promoted profits interest in the venture for cash totaling approximately $210.9 million, which amount was reduced by approximately $24.1 million, consisting of the repayment of the Company’s preferred equity and preferred return as provided for in the amended venture agreement.

On April 1, 2019, the Company completed the acquisition of its partner’s 5% ownership interest and promoted profits interest in the consolidated entity for cash totaling approximately $210.9 million, which amount was reduced by approximately $24.1 million to $186.8 million to reflect the repayment of the Company’s preferred equity and preferred return in the venture, as described above. The Company now owns 100% of Salesforce Tower. The Company has accounted for the transaction as an equity transaction for financial reporting purposes and has reflected the difference between the fair value of the total consideration paid and the related carrying value of the noncontrolling interest - property partnership totaling approximately $162.5 million as a decrease to Additional Paid-in Capital and Partners’ Capital in the Consolidated Balance Sheets of Boston Properties, Inc. and Boston Properties Limited Partnership, respectively.

On June 6, 2017, in conjunction with the refinancing of the indebtedness of the Company’s consolidated entity in which it has a 60% interest and that owns 767 Fifth Avenue (the General Motors Building) located in New York City, the members of the consolidated entity amended the limited liability company agreement to provide for the contribution of the remaining unpaid principal balance of the members’ notes payable totaling approximately $273.9 million (of which the Company’s share of approximately $164.4 million is eliminated in consolidation) to equity in the consolidated entity, resulting in an increase of approximately $109.6 million to Noncontrolling Interests in Property Partnerships on the Company’s Consolidated Balance Sheets. There were no changes to the ownership interests or rights of the members as a result of the amendment.

Stockholders' Equity / Partners' Capital

12 Months Ended

Dec. 31, 2019

Equity [Abstract]

Stockholders' Equity / Partners' Capital

11. Stockholders’ Equity / Partners’ Capital

Boston Properties, Inc.

As of December 31, 2019, Boston Properties, Inc. had 154,790,298 shares of Common Stock outstanding.

As of December 31, 2019, Boston Properties, Inc. owned 1,726,980 general partnership units and 153,063,318 limited partnership units in Boston Properties Limited Partnership.

On June 2, 2017, Boston Properties, Inc. renewed its “at the market” (“ATM”) stock offering program through which it may sell from time to time up to an aggregate of $600.0 million of its common stock through sales agents over a three-year period. This program replaced the Company’s prior $600.0 million ATM stock offering program that was scheduled to expire on June 3, 2017. The Company intends to use the net proceeds from any offering for general business purposes, which may include investment opportunities and debt reduction. No shares of common stock have been issued under this ATM stock offering program.

During the year ended December 31, 2019, Boston Properties, Inc. issued 145,088 shares of Common Stock upon the exercise of options to purchase Common Stock. During the year ended December 31, 2018, there were no options to purchase Common Stock exercised.

During the years ended December 31, 2019 and 2018, Boston Properties, Inc. issued 144,481 and 83,136 shares of Common Stock, respectively, in connection with the redemption of an equal number of redeemable OP Units from limited partners.

The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per OP Unit and LTIP Unit paid or payable in 2019 and 2018:



Record Date	Payment Date	Dividend (Per Share)		Distribution (Per Unit)
December 31, 2019	January 30, 2020		$0.98		$0.98
September 30, 2019	October 31, 2019		$0.95		$0.95
June 28, 2019	July 31, 2019		$0.95		$0.95
March 29, 2019	April 30, 2019		$0.95		$0.95

December 31, 2018	January 30, 2019		$0.95		$0.95
September 28, 2018	October 31, 2018		$0.95		$0.95
June 29, 2018	July 31, 2018		$0.80		$0.80
March 29, 2018	April 30, 2018		$0.80		$0.80
December 29, 2017	January 30, 2018		$0.80		$0.80

Preferred Stock

As of December 31, 2019, Boston Properties, Inc. had 80,000 shares (8,000,000 depositary shares each representing 1/100th of a share) outstanding of its 5.25% Series B Cumulative Redeemable Preferred Stock with a liquidation preference of $2,500.00 per share ($25.00 per depositary share). Boston Properties, Inc. pays cumulative cash dividends on the Series B Preferred Stock at a rate of 5.25% per annum of the $2,500.00 liquidation preference per share. Boston Properties, Inc. did not redeem the Series B Preferred Stock prior to March 27, 2018, except in certain circumstances relating to the preservation of Boston Properties, Inc.’s REIT status. On and after March 27, 2018, Boston Properties, Inc., at its option, may redeem the Series B Preferred Stock for a cash redemption price of $2,500.00 per share ($25.00 per depositary share), plus all accrued and unpaid dividends. The Series B Preferred Stock is not redeemable by the holders, has no maturity date and is not convertible into any other security of Boston Properties, Inc. or its affiliates.

The following table presents Boston Properties Inc.’s dividends per share on its outstanding Series B Preferred Stock paid or payable in 2019 and 2018:



Record Date	Payment Date	Dividend (Per Share)
February 4, 2020	February 18, 2020		$32.8125
November 1, 2019	November 15, 2019		$32.8125
August 2, 2019	August 15, 2019		$32.8125
May 3, 2019	May 15, 2019		$32.8125

February 4, 2019	February 15, 2019		$32.8125
November 2, 2018	November 15, 2018		$32.8125
August 3, 2018	August 15, 2018		$32.8125
May 4, 2018	May 15, 2018		$32.8125
February 2, 2018	February 15, 2018		$32.8125

Future Minimum Rents

12 Months Ended

Dec. 31, 2019

Future Minimum Rents [Abstract]

Future Minimum Rents [Text Block]

12. Future Minimum Rents

On January 1, 2019, the Company adopted ASU 2016-02, “Leases” (see “New Accounting Pronouncements Adopted—Leases” section of Note 2).

The Company’s properties are leased to tenants under operating leases with initial term expiration dates ranging from 2020 to 2049.

The future contractual minimum lease payments to be received (excluding operating expense reimbursements) by the Company as of December 31, 2018, under non-cancelable operating leases which expire on various dates through 2049:



Years Ending December 31,	(in thousands)
2019	$	2,088,171
2020	2,106,963
2021	2,015,031
2022	1,838,699
2023	1,736,636
Thereafter	12,295,464

The future contractual lease payments to be received (excluding operating expense reimbursements) by the Company as of December 31, 2019, under non-cancelable operating leases which expire on various dates through 2049:



Years Ending December 31,	(in thousands)
2020	$	2,205,675
2021	2,222,643
2022	2,126,968
2023	2,068,871
2024	1,974,144
Thereafter	13,892,504

No single tenant represented more than 10.0% of the Company’s total rental revenue for the years ended December 31, 2018 and 2017 and no single tenant represented more than 10.0% of the Company’s total lease revenue for the year ended December 31, 2019.

Segment Information

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

13. Segment Information

The following tables present reconciliations of Net Income Attributable to Boston Properties, Inc. Common Shareholders to the Company’s share of Net Operating Income and Net Income Attributable to Boston Properties Limited Partnership Common Unitholders to the Company’s share of Net Operating Income for the years ended December 31, 2019, 2018 and 2017.

Boston Properties, Inc.



	Year ended December 31,
	2019		2018			2017
	(in thousands)
Net income attributable to Boston Properties, Inc. common shareholders	$	511,034	$	572,347		$	451,939
Add:
Preferred dividends	10,500		10,500			10,500
Noncontrolling interest—common units of the Operating Partnership	59,345		66,807			52,210
Noncontrolling interests in property partnerships	71,120		62,909			47,832
Interest expense	412,717		378,168			374,481
Losses (gains) from early extinguishments of debt	29,540		16,490			(496		)
Impairment losses	24,038		11,812			—
Net operating income from unconsolidated joint ventures	97,716		79,893			64,008
Depreciation and amortization expense	677,764		645,649			617,547
Transaction costs	1,984		1,604			668
Payroll and related costs from management services contracts	10,386		9,590			—
General and administrative expense	140,777		121,722			113,715
Less:
Net operating income attributable to noncontrolling interests in property partnerships	183,989		177,365			174,245
Gains (losses) from investments in securities	6,417		(1,865		)	3,678
Interest and other income	18,939		10,823			5,783
Gains on sales of real estate	709		182,356			7,663
Income from unconsolidated joint ventures	46,592		2,222			11,232
Direct reimbursements of payroll and related costs from management services contracts	10,386		9,590			—
Development and management services revenue	40,039		45,158			34,605
Company’s share of Net Operating Income	$	1,739,850	$	1,551,842		$	1,495,198

Boston Properties Limited Partnership



	Year ended December 31,
		2019		2018			2017
		(in thousands)
Net income attributable to Boston Properties Limited Partnership common unitholders		$	580,102	$	656,903		$	512,866
Add:
Preferred distributions		10,500		10,500			10,500
Noncontrolling interests in property partnerships		71,120		62,909			47,832
Interest expense		412,717		378,168			374,481
Losses (gains) from early extinguishments of debt		29,540		16,490			(496		)
Impairment losses		22,272		10,181			—
Net operating income from unconsolidated joint ventures		97,716		79,893			64,008
Depreciation and amortization expense		669,956		637,891			609,407
Transaction costs		1,984		1,604			668
Payroll and related costs from management services contracts		10,386		9,590			—
General and administrative expense		140,777		121,722			113,715
Less:
Net operating income attributable to noncontrolling interests in property partnerships		183,989		177,365			174,245
Gains (losses) from investments in securities		6,417		(1,865		)	3,678
Interest and other income		18,939		10,823			5,783
Gains on sales of real estate		858		190,716			8,240
Income from unconsolidated joint ventures		46,592		2,222			11,232
Direct reimbursements of payroll and related costs from management services contracts		10,386		9,590			—
Development and management services revenue		40,039		45,158			34,605
Company’s share of Net Operating Income		$	1,739,850	$	1,551,842		$	1,495,198

Net operating income (“NOI”) is a non-GAAP financial measure equal to net income attributable to Boston Properties, Inc. common shareholders and net income attributable to Boston Properties Limited Partnership common unitholders, as applicable, the most directly comparable GAAP financial measures, plus (1) preferred dividends/distributions, net income attributable to noncontrolling interests, interest expense, losses (gains) from early extinguishments of debt, impairment losses, depreciation and amortization expense, transaction costs, payroll and related costs from management services contracts and corporate general and administrative expense less (2) gains (losses) from investments in securities, interest and other income, gains on sales of real estate, income from unconsolidated joint ventures, direct reimbursements of payroll and related costs from management services contracts and development and management services revenue. The Company believes NOI is useful to investors as a performance measure and believes it provides useful information to investors regarding its results of operations and financial condition because, when compared across periods, it reflects the impact on operations from trends in occupancy rates, rental rates, operating costs and acquisition and development activity on an unleveraged basis, providing perspective not immediately apparent from net income attributable to Boston Properties, Inc. common shareholders and net income attributable to Boston Properties Limited Partnership common unitholders. For example, interest expense is not necessarily linked to the operating performance of a real estate asset and is often incurred at the corporate level as opposed to the property level. Similarly, interest expense may be incurred at the property level even though the financing proceeds may be used at the corporate level (e.g., used for other investment activity). In addition, depreciation and amortization expense, because of historical cost accounting and useful life estimates, may distort operating performance measures at the property level. NOI presented by the Company may not be comparable to NOI reported by other REITs or real estate companies that define NOI differently.

Asset information by segment is not reported because the Company does not use this measure to assess performance. Therefore, depreciation and amortization expense is not allocated among segments. Preferred dividends/distributions, interest expense, losses (gains) from early extinguishments of debt, impairment losses, depreciation and amortization expense, transaction costs, payroll and related costs from management services contracts, corporate general and administrative expense, gains (losses) from investments in securities, interest and other income, gains on sales of real estate, direct reimbursements of payroll and related costs from management services contracts and development and management services revenue are not included in NOI and are provided as reconciling items to the Company’s reconciliations of its share of NOI to net income attributable to common shareholders/unitholders.

The Company’s segments are based on the Company’s method of internal reporting which classifies its operations by geographic area. The Company’s segments by geographic area are Boston, Los Angeles, New York, San Francisco and Washington, DC. The Company also presents information for each segment by property type, including Office, Residential and Hotel.

Beginning in 2019, the Company modified the presentation of its geographic area classification for all periods presented to include the Los Angeles geographic area to align with its method of internal reporting. The Company expanded its presence in the Los Angeles geographic area with its equity method investment in Santa Monica Business Park located in Santa Monica, California. As of December 31, 2019, the Company has equity interests in a portfolio of 27 office and retail properties in the Los Angeles geographic area aggregating approximately 2.3 million net rentable square feet, all of which are owned through investments in unconsolidated joint ventures. The Company began presenting the Los Angeles geographic area as a reportable segment to align with its method of internal reporting given the increased significance as a result of commencing a full reporting period of ownership of the Santa Monica Business Park portfolio. The inclusion of the Los Angeles geographic area has also resulted in a change in the reported measure of segment profit or loss from NOI to the Company’s share of NOI. This change has been reflected in all periods presented and the impact of the change can been seen within the tables below. The Company has not presented rental revenue and rental expenses for properties owned through investments in unconsolidated joint ventures, including those in the Los Angeles geographic area, as the Company accounts for these properties using the equity method of accounting.

Information by geographic area and property type (dollars in thousands):

For the year ended December 31, 2019:



	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	895,098		$	—		$	1,011,912		$	533,189		$	384,435		$	2,824,634
Residential	13,786			—			—			—			23,128			36,914
Hotel	48,589			—			—			—			—			48,589
Total	957,473			—			1,011,912			533,189			407,563			2,910,137
% of Grand Totals	32.90		%	—		%	34.78		%	18.32		%	14.00		%	100.00		%
Rental Expenses:
Office	322,282			—			389,532			177,994			144,217			1,034,025
Residential	5,071			—			—			—			10,914			15,985
Hotel	34,004			—			—			—			—			34,004
Total	361,357			—			389,532			177,994			155,131			1,084,014
% of Grand Totals	33.34		%	—		%	35.93		%	16.42		%	14.31		%	100.00		%
Net operating income	$	596,116		$	—		$	622,380		$	355,195		$	252,432		$	1,826,123
% of Grand Totals	32.64		%	—		%	34.09		%	19.45		%	13.82		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(40,109		)	—			(143,432		)	(448		)	—			(183,989		)
Add: Company’s share of net operating income from unconsolidated joint ventures	5,494			61,338			4,174			—			26,710			97,716
Company’s share of net operating income	$	561,501		$	61,338		$	483,122		$	354,747		$	279,142		$	1,739,850
% of Grand Totals	32.27		%	3.53		%	27.77		%	20.39		%	16.04		%	100.00		%

_______________


(1)	Rental Revenue is equal to Total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

For the year ended December 31, 2018:



	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	838,341		$	—		$	959,050		$	397,180		$	396,088		$	2,590,659
Residential	6,694			—			—			—			15,857			22,551
Hotel	49,118			—			—			—			—			49,118
Total	894,153			—			959,050			397,180			411,945			2,662,328
% of Grand Totals	33.59		%	—		%	36.02		%	14.92		%	15.47		%	100.00		%
Rental Expenses:
Office	315,653			—			377,992			130,016			142,886			966,547
Residential	3,632			—			—			—			8,972			12,604
Hotel	33,863			—			—			—			—			33,863
Total	353,148			—			377,992			130,016			151,858			1,013,014
% of Grand Totals	34.86		%	—		%	37.32		%	12.83		%	14.99		%	100.00		%
Net operating income	$	541,005		$	—		$	581,058		$	267,164		$	260,087		$	1,649,314
% of Grand Totals	32.80		%	—		%	35.23		%	16.20		%	15.77		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(33,862		)	—			(143,562		)	59			—			(177,365		)
Add: Company’s share of net operating income from unconsolidated joint ventures	2,866			42,750			6,590			—			27,687			79,893
Company’s share of net operating income	$	510,009		$	42,750		$	444,086		$	267,223		$	287,774		$	1,551,842
% of Grand Totals	32.86		%	2.75		%	28.63		%	17.22		%	18.54		%	100.00		%

_______________


(1)	Rental Revenue is equal to total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

For the year ended December 31, 2017:



	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	776,279		$	—		$	969,371		$	345,519		$	414,103		$	2,505,272
Residential	4,745			—			—			—			11,851			16,596
Hotel	45,603			—			—			—			—			45,603
Total	826,627			—			969,371			345,519			425,954			2,567,471
% of Grand Totals	32.20		%	—		%	37.75		%	13.46		%	16.59		%	100.00		%
Rental Expenses:
Office	301,097			—			372,810			105,253			144,515			923,675
Residential	2,044			—			—			—			4,258			6,302
Hotel	32,059			—			—			—			—			32,059
Total	335,200			—			372,810			105,253			148,773			962,036
% of Grand Totals	34.84		%	—		%	38.76		%	10.94		%	15.46		%	100.00		%
Net operating income	$	491,427		$	—		$	596,561		$	240,266		$	277,181		$	1,605,435
% of Grand Totals	30.61		%	—		%	37.15		%	14.97		%	17.27		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(31,857		)	—			(142,916		)	528			—			(174,245		)
Add: Company’s share of net operating income from unconsolidated joint ventures	1,962			26,816			8,832			—			26,398			64,008
Company’s share of net operating income	$	461,532		$	26,816		$	462,477		$	240,794		$	303,579		$	1,495,198
% of Grand Totals	30.87		%	1.79		%	30.94		%	16.10		%	20.30		%	100.00		%

_______________

(1)

Rental Revenue is equal to total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

Earnings Per Share / Common Unit

12 Months Ended

Dec. 31, 2019

Earnings Per Share [Abstract]

Earnings Per Share / Common Unit

14. Earnings Per Share / Common Unit

Boston Properties, Inc.

The following table provides a reconciliation of both the net income attributable to Boston Properties, Inc. common shareholders and the number of common shares used in the computation of basic earnings per share (“EPS”), which is calculated by dividing net income attributable to Boston Properties, Inc. common shareholders by the weighted-average number of common shares outstanding during the period. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of Boston Properties, Inc. and Boston Properties Limited Partnership’s LTIP Units, 2012 OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic EPS of Boston Properties, Inc. using the two-class method. Participating securities are included in the computation of diluted EPS of Boston Properties, Inc. using the if-converted method if the impact is dilutive. Because the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units required, and the 2017-2019 MYLTIP Units require, Boston Properties, Inc. to outperform absolute and relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, Boston Properties, Inc. excludes such units from the diluted EPS calculation. Other potentially dilutive common shares, including stock options, restricted stock and other securities of Boston Properties Limited Partnership that are exchangeable for Boston Properties, Inc.’s Common Stock, and the related impact on earnings, are considered when calculating diluted EPS.



	For the Year Ended December 31, 2019
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	511,034		154,582	$	3.31
Effect of Dilutive Securities:
Stock Based Compensation	—			301	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	511,034		154,883	$	3.30

	For the Year ended December 31, 2018
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	572,347		154,427	$	3.71
Allocation of undistributed earnings to participating securities	(101		)	—	—
Net income attributable to Boston Properties, Inc. common shareholders	$	572,246		154,427	$	3.71
Effect of Dilutive Securities:
Stock Based Compensation	—			255	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	572,246		154,682	$	3.70

	For the Year ended December 31, 2017
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	451,939		154,190	$	2.93
Effect of Dilutive Securities:
Stock Based Compensation	—			200	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	451,939		154,390	$	2.93

Boston Properties Limited Partnership

The following table provides a reconciliation of both the net income attributable to Boston Properties Limited Partnership common unitholders and the number of common units used in the computation of basic earnings per common unit, which is calculated by dividing net income attributable to Boston Properties Limited Partnership common unitholders by the weighted-average number of common units outstanding during the period. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of Boston Properties, Inc. and Boston Properties Limited Partnership’s LTIP Units, 2012 OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic earnings per common unit using the two-class method. Participating securities are included in the computation of diluted earnings per common unit using the if-converted method if the impact is dilutive. Because the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units, 2015 MYLTIP Units and 2016 MYLTIP Units required, and the 2017-2019 MYLTIP Units require, Boston Properties, Inc. to outperform absolute and relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, Boston Properties Limited Partnership excludes such units from the diluted earnings per common unit calculation. Other potentially dilutive common units and the related impact on earnings are considered when calculating diluted earnings per common unit. Included in the number of units (the denominator) below are approximately 17,618,000, 17,485,000 and 17,471,000 redeemable common units for the years ended December 31, 2019, 2018 and 2017, respectively.



	For the Year Ended December 31, 2019
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	580,102	172,200	$	3.37
Effect of Dilutive Securities:
Stock Based Compensation	—		301	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	580,102	172,501	$	3.36



	For the Year ended December 31, 2018
	Income (Numerator)			Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	656,903		171,912	$	3.82
Allocation of undistributed earnings to participating securities	(113		)	—	—
Net income attributable to Boston Properties Limited Partnership common unitholders	$	656,790		171,912	$	3.82
Effect of Dilutive Securities:
Stock Based Compensation	—			255	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	656,790		172,167	$	3.81



	For the Year ended December 31, 2017
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	512,866	171,661	$	2.99
Effect of Dilutive Securities:
Stock Based Compensation	—		200	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	512,866	171,861	$	2.98

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2019
Employee Benefit Plans [Abstract]
Compensation and Employee Benefit Plans [Text Block]	15. Employee Benefit Plans Effective January 1, 1985, the predecessor of the Company adopted a 401(k) Savings Plan (the “Plan”) for its employees. Upon formation, the Company adopted the Plan and the terms of the Plan. Under the Plan, as amended, the Company’s matching contribution equals 200% of the first 3% of participant’s eligible earnings contributed (utilizing earnings that are not in excess of an amount established by the IRS ($280,000, $275,000 and $270,000 in 2019, 2018 and 2017, respectively), indexed for inflation) with no vesting requirement. The Company’s aggregate matching contribution for the years ended December 31, 2019, 2018 and 2017 was approximately $4.2 million, $4.1 million and $4.1 million, respectively. The Company also maintains a deferred compensation plan that is designed to allow officers of Boston Properties, Inc. to defer a portion of the officer’s current income on a pre-tax basis and receive a tax-deferred return on these deferrals based on the performance of specific investments selected by the officer. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2019 and 2018, the Company had maintained approximately $36.0 million and $28.2 million, respectively, in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the plan participants and earnings on the deferred compensation pursuant to investments elected by the plan participants. The Company’s liability as of December 31, 2019 and 2018 was approximately $36.0 million and $28.2 million, respectively, which are included in the accompanying Consolidated Balance Sheets.

Stock Option and Incentive Plan

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Option and Incentive Plan

16. Stock Option and Incentive Plan

At Boston Properties, Inc.’s 2012 annual meeting of stockholders held on May 15, 2012, its stockholders approved the Boston Properties, Inc. 2012 Stock Option and Incentive Plan (the “2012 Plan”). The 2012 Plan replaced the 1997 Stock Option and Incentive Plan (the “1997 Plan”). The material terms of the 2012 Plan include, among other things: (1) the maximum number of shares of common stock reserved and available for issuance under the 2012 Plan is the sum of (i) 13,000,000 newly authorized shares, plus (ii) the number of shares available for grant under the 1997 Stock Plan immediately prior to the effective date of the 2012 Plan, plus (iii) any shares underlying grants under the 1997 Plan that are forfeited, canceled or terminated (other than by exercise) in the future; (2) “full-value” awards (i.e., awards other than stock options) are multiplied by a 2.32 conversion ratio to calculate the number of shares available under the 2012 Plan that are used for each full-value award, as opposed to a 1.0 conversion ratio for each stock option awarded under the 2012 Plan; (3) shares tendered or held back for taxes will not be added back to the reserved pool under the 2012 Plan; (4) stock options may not be re-priced without stockholder approval; and (5) the term of the 2012 Plan is for 10 years from the date of stockholder approval.

On February 5, 2019, Boston Properties, Inc.’s Compensation Committee approved the 2019 MYLTIP awards under the 2012 Plan to certain officers and employees of Boston Properties, Inc. The 2019 MYLTIP awards utilize Boston Properties, Inc.’s TSR over a three-year measurement period, on an annualized, compounded basis, as the performance metric. Earned awards will be based on Boston Properties, Inc.’s TSR relative to the Nareit Office Index, adjusted to include Vornado Realty Trust. Earned awards will range from zero to a maximum of 220,734

LTIP Units depending on Boston Properties, Inc.’s TSR relative to the Nareit Office Index, adjusted to include Vornado Realty Trust, with a target of approximately 110,367 LTIP Units and linear interpolation between zero and maximum. Earned awards (if any) will vest 50% on February 4, 2022 and 50% on February 4, 2023, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by Boston Properties, Inc. without cause, or termination of employment by the award recipient for good reason, death, disability or retirement. If there is a change of control prior to February 4, 2022, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2019 MYLTIP awards are in the form of LTIP Units issued on the grant date which (i) are subject to forfeiture to the extent awards are not earned and (ii) prior to the performance measurement date are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units. Under ASC 718 “Compensation - Stock Compensation”, the 2019 MYLTIP awards have an aggregate value of approximately $13.5 million, which amount will generally be amortized into earnings over the four year plan period under the graded vesting method.

Boston Properties, Inc. issued 26,503, 20,320 and 37,414 shares of restricted common stock and Boston Properties Limited Partnership issued 181,919, 205,838 and 113,918 LTIP Units to employees and non-employee directors under the 2012 Plan during the years ended December 31, 2019, 2018 and 2017, respectively. Boston Properties, Inc. did not issue any non-qualified stock options under the 2012 Plan during the years ended December 31, 2019, 2018 and 2017. Boston Properties Limited Partnership issued 220,734 2019 MYLTIP Units, 342,659 2018 MYLTIP Units and 400,000 2017 MYLTIP Units to employees under the 2012 Plan during the years ended December 31, 2019, 2018 and 2017, respectively. Employees and non-employee directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit, OPP Unit and MYLTIP Unit. When issued, LTIP Units are not economically equivalent in value to a share of Common Stock, but over time can increase in value to one-for-one parity with Common Stock if there is sufficient appreciation in the value of the Company’s assets. The aggregate value of the LTIP Units is included in noncontrolling interests in the Consolidated Balance Sheets. Grants of restricted stock and LTIP Units to employees vest in four equal annual installments. Restricted stock is measured at fair value on the date of grant based on the number of shares granted and the closing price of Boston Properties, Inc.’s Common Stock on the date of grant as quoted on the New York Stock Exchange. Such value is recognized as an expense ratably over the corresponding employee service period. Non-qualified stock options, which are valued using the Black-Scholes option-pricing model, are recognized as an expense ratably over the corresponding employee service period. As the 2012 OPP Awards, 2013 MYLTIP Awards, 2014 MYLTIP Awards, 2015 MYLTIP Awards, 2016 MYLTIP Awards, 2017 MYLTIP Awards, 2018 MYLTIP Awards and 2019 MYLTIP Awards are subject to both a service condition and a market condition, the Company recognizes the compensation expense related to the 2012 OPP Awards, 2013 MYLTIP Awards, 2014 MYLTIP Awards, 2015 MYLTIP Awards 2016 MYLTIP Awards, 2017 MYLTIP Awards, 2018 MYLTIP Awards and 2019 MYLTIP Awards under the graded vesting attribution method. Under the graded vesting attribution method, each portion of the award that vests at a different date is accounted for as a separate award and recognized over the period appropriate to that portion so that the compensation cost for each portion should be recognized in full by the time that portion vests. The Company recognizes forfeitures as they occur on its awards of stock-based compensation. Dividends paid on both vested and unvested shares of restricted stock are charged directly to Dividends in Excess of Earnings in Boston Properties, Inc.’s Consolidated Balance Sheets and Partners’ Capital in Boston Properties Limited Partnership’s Consolidated Balance Sheets. Aggregate stock-based compensation expense associated with restricted stock, non-qualified stock options, LTIP Units, 2013 MYLTIP Units, 2014 MYLTIP Units, 2015 MYLTIP Units, 2016 MYLTIP Units, 2017 MYLTIP Units, 2018 MYLTIP Units and 2019 MYLTIP Units was approximately $39.8 million, $38.0 million and $33.2 million for the years ended December 31, 2019, 2018 and 2017, respectively. At December 31,

2019, there was (1) an aggregate of approximately $23.3 million of unrecognized compensation expense related to unvested restricted stock and LTIP Units and (2) an aggregate of approximately $12.4 million of unrecognized compensation expense related to unvested 2017 MYLTIP Units, 2018 MYLTIP Units and 2019 MYLTIP Units that is expected to be recognized over a weighted-average period of approximately 2.4 years.

The shares of restricted stock were valued at approximately $3.5 million ($131.27 per share weighted-average), $2.4 million ($119.27 per share weighted-average) and $4.9 million ($130.32 per share weighted-average) for the years ended December 31, 2019, 2018 and 2017, respectively.

LTIP Units were valued using a Monte Carlo simulation method model in accordance with the provisions of ASC 718. LTIP Units issued during the years ended December 31, 2019, 2018 and 2017 were valued at approximately $22.1 million, $22.7 million and $13.6 million, respectively. The weighted-average per unit fair value of LTIP Unit grants in 2019, 2018 and 2017 was $121.50, $110.29 and $119.41, respectively. The per unit fair value of each LTIP Unit granted in 2019, 2018 and 2017 was estimated on the date of grant using the following assumptions; an expected life of 5.7 years, 5.7 years and 5.7 years, a risk-free interest rate of 2.68%, 2.63% and 2.14% and an expected price volatility of 27.0%, 27.0% and 28.0%, respectively.

There were no non-qualified stock options granted during the years ended December 31, 2019, 2018 and 2017.

A summary of the status of Boston Properties, Inc.’s stock options as of December 31, 2019, 2018 and 2017 and changes during the years then ended are presented below:



	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2016	547,129		$	96.38
Exercised	(6,688	)	$	99.15
Outstanding at December 31, 2017	540,441		$	96.35
Exercised	—		$	—
Outstanding at December 31, 2018	540,441		$	96.35
Exercised	(145,088	)	$	96.27
Outstanding at December 31, 2019	395,353		$	96.37

The following table summarizes information about Boston Properties, Inc.’s stock options outstanding at December 31, 2019:



Options Outstanding				Options Exercisable
Number Outstanding at 12/31/19	Weighted-Average Remaining Contractual Life	Exercise Price		Number Exercisable at 12/31/19	Exercise Price
81,458	1.1 years	$	86.86	81,458	$	86.86
54,282	3.3 years	$	95.69	54,282	$	95.69
142,422	3.1 years	$	98.46	142,422	$	98.46
117,191	2.1 years	$	100.77	117,191	$	100.77

The total intrinsic value of the outstanding and exercisable stock options as of December 31, 2019 was approximately $16.4 million. In addition, Boston Properties, Inc. had 540,441 options exercisable at a weighted-average exercise price of $96.35 at December 31, 2018 and 2017.

Boston Properties, Inc. adopted the 1999 Non-Qualified Employee Stock Purchase Plan (the “Stock Purchase Plan”) to encourage the ownership of Common Stock by eligible employees. The Stock Purchase Plan became effective on January 1, 1999 with an aggregate maximum of 250,000 shares of Common Stock available for issuance. The Stock Purchase Plan provides for eligible employees to purchase on the business day immediately following the end of the biannual purchase periods (i.e., January 1-June 30 and July 1-December 31) shares of Common Stock at a purchase price equal to 85% of the average closing prices of the Common Stock during the last ten business days of the purchase period. Boston Properties, Inc. issued 5,862, 6,268 and 6,317 shares with the weighted-average purchase price equal to $104.11 per share, $107.20 per share and $105.97 per share under the Stock Purchase Plan during the years ended December 31, 2019, 2018 and 2017, respectively.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2019
Related Party Transaction [Line Items]
Related Party Transactions Disclosure [Text Block]	17. Related Party Transactions A firm controlled by Mr. Raymond A. Ritchey’s brother was paid aggregate leasing commissions of approximately $21,000, $921,000 and $368,000 for the years ended December 31, 2019, 2018 and 2017, respectively, related to certain exclusive leasing arrangements for certain Northern Virginia properties. Mr. Ritchey is a Senior Executive Vice President of Boston Properties, Inc. In accordance with Boston Properties, Inc.’s 2012 Plan, and as approved by its Board of Directors, seven non-employee directors made elections to receive deferred stock units in lieu of cash fees for 2019. As a result of these elections, the aggregate cash fees otherwise payable to a non-employee director during a fiscal quarter are converted into a number of deferred stock units equal to the aggregate cash fees divided by the last reported sales price of a share of Boston Properties, Inc.’s Common Stock on the last trading of the applicable fiscal quarter. The deferred stock units are also credited with dividend equivalents as dividends are paid by Boston Properties, Inc. The deferred stock units may be settled in shares of Common Stock upon the cessation of such director’s service on the Board of Directors of Boston Properties, Inc. The Company modified the terms of the non-employee director compensation program to provide, subject to certain conditions, the non-employee directors holding deferred stock units with the ability to elect, following cessation of their service on the Company’s Board of Directors, to diversify their investment elections into non-employer securities on a pre-tax basis and receive tax-deferred returns on such deferrals, which will ultimately be settled in cash. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the non-employee director in the future. At December 31, 2019, the Company had maintained approximately $0.7 million in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the non-employee director and earnings on the deferred compensation pursuant to investments elected by the non-employee director. The Company’s liability as of December 31, 2019 was approximately $0.7 million, which is included in the accompanying Consolidated Balance Sheets. The modification of the terms of the non-employee director compensation program required a change to the classification of these deferred stock units from permanent equity to temporary equity on the Consolidated Balance Sheets of Boston Properties, Inc. and Boston Properties Limited Partnership within Redeemable Deferred Stock Units (See Note 2). On May 21, 2019, in connection with the cessation of a director’s service on the Board of Directors of Boston Properties, Inc., Boston Properties, Inc. issued 17,949 shares of Common Stock in settlement of a portion of the director’s outstanding deferred stock units. In addition, on September 3, 2019, the Company converted 4,917 of such director’s deferred stock units as a result of such director’s election to diversify their investment elections into non-employer securities. On May 23, 2018, in connection with the cessation of a director’s service on the Board of Directors of Boston Properties, Inc., Boston Properties, Inc. issued 36,836 shares of Common Stock in settlement of the director’s outstanding deferred stock units. At December 31, 2019 and 2018, Boston Properties, Inc. had outstanding 60,676 and 74,966 deferred stock units, respectively.

Selected Interim Financial Information (unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information [Text Block]

18. Selected Interim Financial Information (unaudited)

Boston Properties, Inc.

The tables below reflect Boston Properties, Inc.’s selected quarterly information for the years ended December 31, 2019 and 2018.



	2019 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per share amounts)
Total revenue	$	725,767	$	733,741	$	743,553	$	757,501
Net income	$	131,159	$	203,461	$	141,370	$	176,009
Net income attributable to Boston Properties, Inc. common shareholders	$	98,105	$	164,318	$	107,771	$	140,824
Income attributable to Boston Properties, Inc. per share—basic	$	0.63	$	1.06	$	0.70	$	0.91
Income attributable to Boston Properties, Inc. per share—diluted	$	0.63	$	1.06	$	0.70	$	0.91



	2018 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per share amounts)
Total revenue	$	661,151	$	664,484	$	686,284	$	705,157
Net income	$	216,312	$	160,565	$	150,445	$	185,241
Net income attributable to Boston Properties, Inc. common shareholders	$	176,021	$	128,681	$	119,118	$	148,529
Income attributable to Boston Properties, Inc. per share—basic	$	1.14	$	0.83	$	0.77	$	0.96
Income attributable to Boston Properties, Inc. per share—diluted	$	1.14	$	0.83	$	0.77	$	0.96

Boston Properties Limited Partnership

The tables below reflect Boston Properties Limited Partnership’s selected quarterly information for the years ended December 31, 2019 and 2018.



	2019 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per unit amounts)
Total revenue	$	725,767	$	733,741	$	743,553	$	757,501
Net income	$	134,837	$	205,822	$	143,212	$	177,851
Net income attributable to Boston Properties Limited Partnership common unitholders	$	113,382	$	185,715	$	122,117	$	158,888
Income attributable to Boston Properties Limited Partnership per unit—basic	$	0.66	$	1.08	$	0.71	$	0.92
Income attributable to Boston Properties Limited Partnership per unit—diluted	$	0.66	$	1.08	$	0.71	$	0.92



	2018 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per unit amounts)
Total revenue	$	661,151	$	664,484	$	686,284	$	705,157
Net income	$	220,766	$	162,986	$	153,676	$	192,884
Net income attributable to Boston Properties Limited Partnership common unitholders	$	200,907	$	145,961	$	136,201	$	173,834
Income attributable to Boston Properties Limited Partnership per unit—basic	$	1.17	$	0.85	$	0.79	$	1.01
Income attributable to Boston Properties Limited Partnership per unit—diluted	$	1.17	$	0.85	$	0.79	$	1.01

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	19. Subsequent Events On January 28, 2020, the Company entered into a joint venture with a third party to own, operate and develop properties at its Gateway Commons complex located in South San Francisco, California. The Company contributed its 601, 611 and 651 Gateway properties and development rights with an agreed upon value aggregating approximately $350.0 million for its 50% interest in the joint venture. 601, 611 and 651 Gateway consist of three Class A office properties aggregating approximately 768,000 net rentable square feet. The partner contributed three properties and development rights with an agreed upon value aggregating approximately $280.8 million at closing and will contribute cash totaling approximately $69.2 million in the future for its 50% ownership interest in the joint venture. On January 28, 2020, a joint venture in which the Company has a 55% interest commenced development of the first phase of its Platform 16 project located in San Jose, California. The first phase of the Platform 16 development project consists of an approximately 390,000 net rentable square foot Class A office building and a below-grade parking garage. On February 20, 2020, the joint venture acquired the land under the ground lease for a purchase price totaling approximately $134.8 million. The joint venture had previously made a deposit totaling $15.0 million, which deposit was credited against the purchase price. Platform 16 consists of a parcel of land totaling approximately 5.6 acres that will support the development of approximately 1.1 million square feet of commercial office space (See Notes 3 and 5). On January 28, 2020, the Company exercised its option to acquire real property at 425 Fourth Street located in San Francisco, California for a purchase price totaling approximately $134.1 million. 425 Fourth Street will support the development of approximately 804,000 square feet of primarily commercial office space. The Company expects to complete the acquisition during the second quarter of 2020. On January 31, 2020 and February 4, 2020, Boston Properties, Inc. issued an aggregate of 24,503 shares of restricted Common Stock and Boston Properties Limited Partnership issued an aggregate of 196,927 LTIP Units under the 2012 Plan to certain employees of Boston Properties, Inc. On February 4, 2020, Boston Properties, Inc.’s Compensation Committee approved the 2020 Multi-Year Long-Term Incentive Program (the “2020 MYLTIP”) awards under Boston Properties, Inc.’s 2012 Plan to certain officers and employees of Boston Properties, Inc. Earned awards will range from zero to a maximum of 203,278 LTIP Units depending on Boston Properties, Inc.’s TSR relative to the FTSE Nareit Office Index, adjusted to include Vornado Realty Trust, with a target of approximately 101,638 LTIP Units and linear interpolation between zero and maximum. Under ASC 718, the 2020 MYLTIP awards have an aggregate value of approximately $13.7 million. On February 6, 2020, the measurement period for the Company’s 2017 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 83.8% of target or an aggregate of approximately $17.6 million (after giving effect to employee separations). As a result, an aggregate of 270,942 2017 MYLTIP Units that had been previously granted were automatically forfeited. On February 20, 2020, the Company completed the sale of its New Dominion Technology Park located in Herndon, Virginia for a gross sale price of $256.0 million. New Dominion Technology Park is comprised of two Class A office properties aggregating approximately 493,000 net rentable square feet (See Note 6).

Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2019

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

Real Estate and Accumulated Depreciation Disclosure [Text Block]

Item 15. Exhibits and Financial Statement Schedules

(a) Financial Statement Schedule

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances		Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

					Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,274,028	$	1,796,252	$	1,532,654	$	202,612	$	1,796,252	$	1,735,266	$	—	$	—	$	3,531,518	$	313,158	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—		92,077		948,357		556,458		115,638		1,478,578		2,676		—		1,596,892		596,740		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—		179,697		847,410		415,228		195,987		1,246,348		—		—		1,442,335		633,711		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—		339,200		700,358		300,519		354,107		985,970		—		—		1,340,077		358,960		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	644,778		241,600		494,782		454,902		289,639		688,550		—		213,095		1,191,284		289,482		1977/1997	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—		200,349		946,205		—		200,349		946,205		—		—		1,146,554		38,727		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—		219,543		667,884		210,160		250,134		829,529		17,924		—		1,097,587		214,533		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—		285,263		603,167		51,928		285,263		655,095		—		—		940,358		116,857		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—		131,067		435,954		102,984		131,067		538,938		—		—		670,005		122,799		1971-1975/2017	2012	(1)
Times Square Tower	Office	New York, NY	—		165,413		380,438		113,222		169,193		489,880		—		—		659,073		217,303		2004	2000	(1)
Carnegie Center	Office	Princeton, NJ	—		142,666		316,856		152,280		94,240		462,882		54,680		—		611,802		208,331		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Atlantic Wharf	Office	Boston, MA	—		63,988		454,537		18,709		63,988		473,246		—		—		537,234		131,828		2011	2007	(1)
510 Madison Avenue	Office	New York, NY	—		103,000		253,665		25,495		103,000		279,160		—		—		382,160		72,213		2012	2010	(1)
Fountain Square	Office	Reston, VA	—		56,853		306,298		12,140		56,853		318,438		—		—		375,291		78,498		1986-1990	2012	(1)
599 Lexington Avenue	Office	New York, NY	—		81,040		100,507		188,572		87,852		282,267		—		—		370,119		183,291		1986	1997	(1)
680 Folsom Street	Office	San Francisco, CA	—		72,545		219,766		7,907		72,545		227,673		—		—		300,218		46,777		2014	2012	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—		—		183,541		113,627		109,038		188,130		—		—		297,168		59,190		2011	2008	(1)
145 Broadway	Office	Cambridge, MA	—		121		273,013		23,246		23,367		273,013		—		—		296,380		1,511		2019	1997	(1)
South of Market and Democracy Tower	Office	Reston, VA	—		13,603		237,479		26,415		13,687		263,810		—		—		277,497		99,478		2008-2009	2003	(1)
601 Massachusetts Avenue	Office	Washington, DC	—		95,310		165,173		3,945		95,322		169,106		—		—		264,428		24,502		2016	2008	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—		18,789		148,451		80,077		18,789		228,528		—		—		247,317		79,824		1985-1989	2011	(1)
Gateway Center	Office	San Francisco, CA	—		28,255		139,245		61,791		30,627		198,664		—		—		229,291		106,680		1984/1986/2002	1999	(1)
535 Mission Street	Office	San Francisco, CA	—		40,933		148,378		3,276		40,933		151,654		—		—		192,587		26,293		2015	2013	(1)
Reservoir Place	Office	Waltham, MA	—		18,605		104,124		53,718		20,108		156,339		—		—		176,447		70,870		1955/1987/2017	1997/1998	(1)
Mountain View Research Park	Office	Mountain View, CA	—		95,066		68,373		12,704		95,066		81,077		—		—		176,143		19,807		1977-1981/2007-2013	2013	(1)
1330 Connecticut Avenue	Office	Washington, DC	—		25,982		82,311		36,847		27,135		118,005		—		—		145,140		32,775		1984/2018	2004	(1)

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances	Original		Costs Capitalized Subsequent to Acquisition		Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

				Land	Building
Kingstowne Towne Center	Office	Alexandria, VA	—	18,021	109,038	3,376		18,062	112,373	—	—	130,435	44,294	2003-2006	2007	(1)
One Freedom Square	Office	Reston, VA	—	9,929	84,504	34,372		11,293	117,512	—	—	128,805	59,006	2000	2003	(1)
Capital Gallery	Office	Washington, DC	—	4,725	29,565	88,704		8,662	114,332	—	—	122,994	71,631	1981/2006	2007	(1)
Weston Corporate Center	Office	Weston, MA	—	25,753	92,312	(123	)	25,854	92,088	—	—	117,942	29,227	2010	2001	(1)
Two Freedom Square	Office	Reston, VA	—	13,930	77,739	23,209		15,420	99,458	—	—	114,878	50,668	2001	2003	(1)
One and Two Reston Overlook	Office	Reston, VA	—	16,456	66,192	24,181		16,179	90,650	—	—	106,829	51,503	1999	2000	(1)
Discovery Square	Office	Reston, VA	—	11,198	71,782	20,905		12,533	91,352	—	—	103,885	43,619	2001	2003	(1)
140 Kendrick Street	Office	Needham, MA	—	18,095	66,905	17,574		19,092	83,482	—	—	102,574	35,721	2000	2004	(1)
355 Main Street	Office	Cambridge, MA	—	18,863	53,346	27,582		21,173	78,618	—	—	99,791	26,439	1981/1996/2013	2006	(1)
880 & 890 Winter Street	Office	Waltham, MA	—	29,510	65,812	—		29,510	65,812	—	—	95,322	1,458	1998-1999	2019	(1)
10 CityPoint	Office	Waltham, MA	—	1,953	85,752	4,697		2,290	90,112	—	—	92,402	10,928	2016	1997	(1)
90 Broadway	Office	Cambridge, MA	—	19,104	52,078	19,857		20,785	70,254	—	—	91,039	23,621	1983/1998/2013	2006	(1)
230 CityPoint	Office	Waltham, MA	—	13,189	49,823	22,057		13,807	71,262	—	—	85,069	29,255	1992	2005	(1)
77 CityPoint	Office	Waltham, MA	—	13,847	60,383	10,556		14,023	70,763	—	—	84,786	27,172	2008	2001	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—	10,385	60,694	13,165		11,097	73,147	—	—	84,244	35,567	2003	1999	(1)
3625-3635 Peterson Way	Office	Santa Clara, CA	—	63,206	14,879	752		63,206	14,879	752	—	78,837	11,172	1979	2016	(1)
2440 West El Camino Real	Office	Mountain View, CA	—	16,741	51,285	5,454		16,741	56,739	—	—	73,480	13,090	1987/2003	2011	(1)
191 Spring Street	Office	Lexington, MA	—	2,850	59,751	7,695		3,151	67,145	—	—	70,296	21,917	1971/1995/2018	1997	(1)
300 Binney Street	Office	Cambridge, MA	—	18,080	51,262	140		18,080	51,402	—	—	69,482	11,146	2013	2009	(1)
Wisconsin Place	Office	Chevy Chase, MD	—	—	53,349	14,924		—	68,273	—	—	68,273	25,934	2009	2004	(1)
Reston Corporate Center	Office	Reston, VA	—	9,135	50,857	6,236		10,148	56,080	—	—	66,228	29,860	1984	1998	(1)
New Dominion Technology Park, Bldg. Two	Office	Herndon, VA	—	5,584	51,868	4,157		6,510	55,099	—	—	61,609	26,894	2004	1998	(1)
255 Main Street	Office	Cambridge, MA	—	134	25,110	34,124		548	58,820	—	—	59,368	33,543	1987	1997	(1)
University Place	Office	Cambridge, MA	3,602	—	37,091	16,001		7,418	45,674	—	—	53,092	29,423	1985	1998	(1)
New Dominion Technology Park, Bldg. One	Office	Herndon, VA	—	3,880	43,227	3,927		4,583	46,451	—	—	51,034	29,141	2001	1998	(1)
Sumner Square	Office	Washington, DC	—	624	28,745	21,344		3,535	47,178	—	—	50,713	27,093	1985	1999	(1)
200 West Street	Office	Waltham, MA	—	16,148	24,983	8,211		16,813	30,425	—	2,104	49,342	17,001	1999	1997	(1)
North First Business Park	Office	San Jose, CA	—	23,398	13,069	4,571		23,377	17,661	—	—	41,038	16,411	1981	2007	(1)
150 Broadway	Office	Cambridge, MA	—	850	25,042	8,540		1,323	33,109	—	—	34,432	19,875	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—	1,299	12,943	11,406		2,395	23,253	—	—	25,648	11,870	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—	998	1,426	18,547		1,264	19,707	—	—	20,971	14,312	1982	1997	(1)
201 Spring Street	Office	Lexington, MA	—	2,849	15,303	1,172		3,124	16,200	—	—	19,324	8,587	1997	1997	(1)
The Point	Office	Waltham, MA	—	6,395	10,040	421		6,492	10,364	—	—	16,856	1,349	2015	2007	(1)
33 Hayden Avenue	Office	Lexington, MA	—	266	3,234	12,898		425	15,973	—	—	16,398	5,678	1979	1997	(1)
690 Folsom Street	Office	San Francisco, CA	—	3,219	11,038	1,157		3,219	12,195	—	—	15,414	2,284	2015	2012	(1)

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances	Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

				Land	Building
92-100 Hayden Avenue	Office	Lexington, MA	—	594	6,748	7,529	802	14,069	—	—	14,871	12,041	1985	1997	(1)
181 Spring Street	Office	Lexington, MA	—	1,066	9,520	2,177	1,160	11,603	—	—	12,763	5,597	1999	1997	(1)
195 West Street	Office	Waltham, MA	—	1,611	6,652	4,218	1,858	10,623	—	—	12,481	8,352	1990	1997	(1)
7501 Boston Boulevard, Building Seven	Office	Springfield, VA	—	665	9,273	816	791	9,963	—	—	10,754	5,393	1997	1997	(1)
7435 Boston Boulevard, Building One	Office	Springfield, VA	—	392	3,822	4,983	659	8,538	—	—	9,197	6,344	1982	1997	(1)
7450 Boston Boulevard, Building Three	Office	Springfield, VA	—	1,165	4,681	2,591	1,430	7,007	—	—	8,437	3,575	1987	1998	(1)
32 Hartwell Avenue	Office	Lexington, MA	—	168	1,943	6,115	314	7,912	—	—	8,226	1,975	1968/1979/1987	1997	(1)
250 Binney Street	Office	Cambridge, MA	—	110	4,483	3,593	273	7,913	—	—	8,186	5,829	1983	1997	(1)
8000 Grainger Court, Building Five	Office	Springfield, VA	—	366	4,282	3,198	601	7,245	—	—	7,846	5,752	1984	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—	5,477	1,090	676	5,477	1,766	—	—	7,243	690	1977	2012	(1)
7300 Boston Boulevard, Building Thirteen	Office	Springfield, VA	—	608	4,773	1,007	661	5,727	—	—	6,388	1,984	2002	1997	(1)
17 Hartwell Avenue	Office	Lexington, MA	—	26	150	6,064	65	6,175	—	—	6,240	1,966	1968	1997	(1)
7601 Boston Boulevard, Building Eight	Office	Springfield, VA	—	200	878	5,060	551	5,587	—	—	6,138	4,689	1986	1997	(1)
7500 Boston Boulevard, Building Six	Office	Springfield, VA	—	138	3,749	1,640	367	5,160	—	—	5,527	4,237	1985	1997	(1)
8000 Corporate Court, Building Eleven	Office	Springfield, VA	—	136	3,071	1,596	774	4,029	—	—	4,803	3,191	1989	1997	(1)
7375 Boston Boulevard, Building Ten	Office	Springfield, VA	—	23	2,685	1,032	93	3,647	—	—	3,740	2,606	1988	1997	(1)
7374 Boston Boulevard, Building Four	Office	Springfield, VA	—	241	1,605	1,828	398	3,276	—	—	3,674	2,779	1984	1997	(1)
7451 Boston Boulevard, Building Two	Office	Springfield, VA	—	249	1,542	1,667	613	2,845	—	—	3,458	2,610	1982	1997	(1)
Signature at Reston	Residential	Reston, VA	—	27,076	190,580	393	27,076	190,973	—	—	218,049	8,773	2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—	9,243	127,248	2,939	9,245	130,185	—	—	139,430	4,566	2018	2015	(1)
The Avant at Reston Town Center	Residential	Reston, VA	—	20,350	91,995	830	20,350	92,825	—	—	113,175	14,728	2014	2010	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—	3,529	54,891	1,897	3,529	56,788	—	—	60,317	12,639	2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—	478	37,918	35,813	1,201	73,008	—	—	74,209	46,605	1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—	—	35,035	7,329	103	42,261	—	—	42,364	13,512	1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—	1,256	15,697	1,552	1,434	17,071	—	—	18,505	6,031	2006	2004	(1)
Kendall Center Blue Garage	Garage	Cambridge, MA	—	1,163	11,633	2,151	1,579	13,368	—	—	14,947	9,728	1990	1997	(1)
The Skylyne (MacArthur Station Residences)	Development	Oakland, CA	—	—	—	226,526	29,807	—	—	196,719	226,526	—	N/A	N/A	N/A
2100 Pennsylvania Avenue	Development	Washington, DC	—	—	—	224,380	185,129	—	—	39,251	224,380	1,024	N/A	N/A	N/A
Reston Gateway	Development	Reston, VA	—	—	—	150,632	—	—	—	150,632	150,632	—	N/A	1998	N/A
17Fifty Presidents Street	Development	Reston, VA	—	—	—	99,816	—	—	—	99,816	99,816	—	N/A	2013	N/A

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances				Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements				Building and Improvements				Land Held for Development				Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

							Land		Building
20 CityPoint	Development	Waltham, MA	—				4,721		52,039		20,007		4,721				52,039				—				20,007		76,767		1,136		N/A	2007	N/A
325 Main Street	Development	Cambridge, MA	—				174		—		68,903		965				—				—				68,112		69,077		—		N/A	1997	N/A
North First Master Plan	Land	San Jose, CA	—				35,004		—		3,932		—				—				38,936				—		38,936		—		N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—				—		—		34,889		—				—				34,889				—		34,889		—		N/A	2006	N/A
425 Fourth Street	Land	San Francisco, CA	—				—		—		22,074		—				—				22,074				—		22,074		—		N/A	N/A	N/A
Springfield Metro Center	Land	Springfield, VA	—				—		—		19,844		—				—				19,844				—		19,844		—		N/A	2007	N/A
Reston Gateway Master Plan	Land	Reston, VA	—				—		—		18,292		—				—				18,292				—		18,292		—		N/A	1998	N/A
214 Third Avenue	Land	Waltham, MA	—				—		—		17,692		—				—				17,692				—		17,692		—		N/A	2006	N/A
103 Fourth Avenue	Land	Waltham, MA	—				—		—		12,826		—				—				12,826				—		12,826		—		N/A	2007	N/A
Crane Meadow	Land	Marlborough, MA	—				—		—		8,866		—				—				8,866				—		8,866		—		N/A	2000	N/A
Broad Run Business Park	Land	Loudoun County, VA	—				—		—		2,396		—				—				2,396				—		2,396		—		N/A	1998	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—				—		—		1,693		—				—				1,693				—		1,693		—		N/A	1997	N/A
Weston Quarry	Land	Weston, MA	—				—		—		1,249		—				—				1,249				—		1,249		—		N/A	2001	N/A
Reston Overlook Master Plan	Land	Reston, VA	—				—		—		39		—				—				39				—		39		—		N/A	2000	N/A

			$	2,922,408	(2	)	$	5,024,060	$	13,057,336	$	4,763,301	$	5,474,337	(3	)	$	16,325,796	(4	)	$	254,828	(5	)	$	789,736	$	22,844,697	$	5,239,179

Note: Total Real Estate does not include Furniture, Fixtures and Equipment totaling approximately $44,313. Accumulated Depreciation does not include approximately $27,619 of accumulated depreciation related to Furniture, Fixtures and Equipment.

The aggregate cost and accumulated depreciation for tax purposes was approximately $18.6 billion and $4.0 billion, respectively.


(1)	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.


(2)	Includes unamortized deferred financing costs totaling approximately $(26.7) million.


(3)	Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $214,091 and $148,640, respectively.


(4)	Includes Right of Use Assets - Finance Leases of approximately $23,303.

(5)

Includes pre-development costs.

Boston Properties, Inc.

Real Estate and Accumulated Depreciation

December 31, 2019, 2018 and 2017

(dollars in thousands)

A summary of activity for real estate and accumulated depreciation is as follows:



	2019			2018			2017
Real Estate:
Balance at the beginning of the year	$	21,605,545		$	21,058,714		$	20,114,576
Additions to/improvements of real estate	1,671,898			1,043,379			1,099,286
Assets sold/written-off	(432,746		)	(496,548		)	(155,148		)
Balance at the end of the year	$	22,844,697		$	21,605,545		$	21,058,714
Accumulated Depreciation:
Balance at the beginning of the year	$	4,871,102		$	4,566,570		$	4,201,891
Depreciation expense	564,938			533,342			497,059
Assets sold/written-off	(196,861		)	(228,810		)	(132,380		)
Balance at the end of the year	$	5,239,179		$	4,871,102		$	4,566,570

Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

Real Estate and Accumulated Depreciation Disclosure [Text Block]

Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

					Original				Costs Capitalized Subsequent to Acquisition			Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances		Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,274,028	$	1,796,252	$	1,532,654	$	202,612		$	1,796,252	$	1,735,266	$	—	$	—	$	3,531,518	$	313,158	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—		92,077		948,357		496,088			100,540		1,433,306		2,676		—		1,536,522		580,797		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—		179,697		847,410		352,847			180,420		1,199,534		—		—		1,379,954		617,163		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—		339,200		700,358		240,911			339,200		941,269		—		—		1,280,469		343,191		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	644,778		241,600		494,782		417,816			279,281		661,822		—		213,095		1,154,198		280,028		1977/1997	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—		200,349		946,205		—			200,349		946,205		—		—		1,146,554		38,727		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—		219,543		667,884		210,160			250,134		829,529		17,924		—		1,097,587		214,533		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—		285,263		603,167		51,928			285,263		655,095		—		—		940,358		116,857		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—		131,067		435,954		102,984			131,067		538,938		—		—		670,005		122,799		1971-1975/2017	2012	(1)
Times Square Tower	Office	New York, NY	—		165,413		380,438		75,243			159,694		461,400		—		—		621,094		207,272		2004	2000	(1)
Carnegie Center	Office	Princeton, NJ	—		142,666		316,856		137,317			90,498		451,661		54,680		—		596,839		204,380		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Atlantic Wharf	Office	Boston, MA	—		63,988		454,537		18,709			63,988		473,246		—		—		537,234		131,828		2011	2007	(1)
510 Madison Avenue	Office	New York, NY	—		103,000		253,665		25,495			103,000		279,160		—		—		382,160		72,213		2012	2010	(1)
Fountain Square	Office	Reston, VA	—		56,853		306,298		12,140			56,853		318,438		—		—		375,291		78,498		1986-1990	2012	(1)
599 Lexington Avenue	Office	New York, NY	—		81,040		100,507		161,330			81,040		261,837		—		—		342,877		176,101		1986	1997	(1)
680 Folsom Street	Office	San Francisco, CA	—		72,545		219,766		7,907			72,545		227,673		—		—		300,218		46,777		2014	2012	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—		—		183,541		113,627			109,038		188,130		—		—		297,168		59,190		2011	2008	(1)
145 Broadway	Office	Cambridge, MA	—		121		273,013		23,043			23,164		273,013		—		—		296,177		1,511		2019	1997	(1)
South of Market and Democracy Tower	Office	Reston, VA	—		13,603		237,479		26,079			13,603		263,558		—		—		277,161		99,406		2008-2009	2003	(1)
601 Massachusetts Avenue	Office	Washington, DC	—		95,310		165,173		3,933			95,310		169,106		—		—		264,416		24,502		2016	2008	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—		18,789		148,451		80,077			18,789		228,528		—		—		247,317		79,824		1985-1989	2011	(1)
Gateway Center	Office	San Francisco, CA	—		28,255		139,245		55,402			29,029		193,873		—		—		222,902		104,993		1984/1986/2002	1999	(1)
535 Mission Street	Office	San Francisco, CA	—		40,933		148,378		3,276			40,933		151,654		—		—		192,587		26,293		2015	2013	(1)
Mountain View Research Park	Office	Mountain View, CA	—		95,066		68,373		12,704			95,066		81,077		—		—		176,143		19,807		1977-1981/2007-2013	2013	(1)
Reservoir Place	Office	Waltham, MA	—		18,605		104,124		49,643			19,089		153,283		—		—		172,372		69,794		1955/1987/2017	1997/1998	(1)
1330 Connecticut Avenue	Office	Washington, DC	—		25,982		82,311		32,234			25,982		114,545		—		—		140,527		31,553		1984/2018	2004	(1)
Kingstowne Towne Center	Office	Alexandria, VA	—		18,021		109,038		3,212			18,021		112,250		—		—		130,271		44,258		2003-2006	2007	(1)
One Freedom Square	Office	Reston, VA	—		9,929		84,504		28,735			9,883		113,285		—		—		123,168		57,516		2000	2003	(1)
Weston Corporate Center	Office	Weston, MA	—		25,753		92,312		(123		)	25,854		92,088		—		—		117,942		29,227		2010	2001	(1)
Capital Gallery	Office	Washington, DC	—		4,725		29,565		78,573			6,128		106,735		—		—		112,863		68,953		1981/2006	2007	(1)
Two Freedom Square	Office	Reston, VA	—		13,930		77,739		16,997			13,866		94,800		—		—		108,666		49,028		2001	2003	(1)

Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

				Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances	Land	Building
One and Two Reston Overlook	Office	Reston, VA	—	16,456	66,192	19,763	15,074	87,337	—	—	102,411	50,336	1999	2000	(1)
355 Main Street	Office	Cambridge, MA	—	18,863	53,346	27,284	21,098	78,395	—	—	99,493	26,362	1981/1996/2013	2006	(1)
140 Kendrick Street	Office	Needham, MA	—	18,095	66,905	13,584	18,095	80,489	—	—	98,584	34,667	2000	2004	(1)
Discovery Square	Office	Reston, VA	—	11,198	71,782	15,360	11,146	87,194	—	—	98,340	42,152	2001	2003	(1)
880 & 890 Winter Street	Office	Waltham, MA	—	29,510	65,812	—	29,510	65,812	—	—	95,322	1,458	1998-1999	2019	(1)
10 CityPoint	Office	Waltham, MA	—	1,953	85,752	4,534	2,127	90,112	—	—	92,239	10,928	2016	1997	(1)
90 Broadway	Office	Cambridge, MA	—	19,104	52,078	19,678	20,741	70,119	—	—	90,860	23,581	1983/1998/2013	2006	(1)
77 CityPoint	Office	Waltham, MA	—	13,847	60,383	10,451	13,997	70,684	—	—	84,681	27,148	2008	2001	(1)
230 CityPoint	Office	Waltham, MA	—	13,189	49,823	20,440	13,403	70,049	—	—	83,452	28,831	1992	2005	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—	10,385	60,694	10,178	10,350	70,907	—	—	81,257	34,777	2003	1999	(1)
3625-3635 Peterson Way	Office	Santa Clara, CA	—	63,206	14,879	752	63,206	14,879	752	—	78,837	11,172	1979	2016	(1)
2440 West El Camino Real	Office	Mountain View, CA	—	16,741	51,285	5,454	16,741	56,739	—	—	73,480	13,090	1987/2003	2011	(1)
191 Spring Street	Office	Lexington, MA	—	2,850	59,751	7,063	2,850	66,814	—	—	69,664	21,801	1971/1995/2018	1997	(1)
300 Binney Street	Office	Cambridge, MA	—	18,080	51,262	140	18,080	51,402	—	—	69,482	11,146	2013	2009	(1)
Wisconsin Place	Office	Chevy Chase, MD	—	—	53,349	14,924	—	68,273	—	—	68,273	25,934	2009	2004	(1)
Reston Corporate Center	Office	Reston, VA	—	9,135	50,857	3,625	9,496	54,121	—	—	63,617	29,170	1984	1998	(1)
New Dominion Technology Park, Bldg. Two	Office	Herndon, VA	—	5,584	51,868	412	5,574	52,290	—	—	57,864	25,900	2004	1998	(1)
255 Main Street	Office	Cambridge, MA	—	134	25,110	32,468	134	57,578	—	—	57,712	33,108	1987	1997	(1)
University Place	Office	Cambridge, MA	3,602	—	37,091	14,551	7,055	44,587	—	—	51,642	29,044	1985	1998	(1)
Sumner Square	Office	Washington, DC	—	624	28,745	19,264	3,015	45,618	—	—	48,633	26,547	1985	1999	(1)
New Dominion Technology Park, Bldg. One	Office	Herndon, VA	—	3,880	43,227	1,117	3,880	44,344	—	—	48,224	28,398	2001	1998	(1)
200 West Street	Office	Waltham, MA	—	16,148	24,983	5,550	16,148	28,429	—	2,104	46,681	16,298	1999	1997	(1)
North First Business Park	Office	San Jose, CA	—	23,398	13,069	4,548	23,371	17,644	—	—	41,015	16,411	1981	2007	(1)
150 Broadway	Office	Cambridge, MA	—	850	25,042	6,535	822	31,605	—	—	32,427	19,342	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—	1,299	12,943	9,300	1,868	21,674	—	—	23,542	11,312	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—	998	1,426	17,783	1,073	19,134	—	—	20,207	14,114	1982	1997	(1)
201 Spring Street	Office	Lexington, MA	—	2,849	15,303	73	2,849	15,376	—	—	18,225	8,295	1997	1997	(1)
The Point	Office	Waltham, MA	—	6,395	10,040	421	6,492	10,364	—	—	16,856	1,349	2015	2007	(1)
33 Hayden Avenue	Office	Lexington, MA	—	266	3,234	12,261	266	15,495	—	—	15,761	5,510	1979	1997	(1)
690 Folsom Street	Office	San Francisco, CA	—	3,219	11,038	1,157	3,219	12,195	—	—	15,414	2,284	2015	2012	(1)
92-100 Hayden Avenue	Office	Lexington, MA	—	594	6,748	6,800	619	13,523	—	—	14,142	11,847	1985	1997	(1)
181 Spring Street	Office	Lexington, MA	—	1,066	9,520	1,800	1,066	11,320	—	—	12,386	5,498	1999	1997	(1)
195 West Street	Office	Waltham, MA	—	1,611	6,652	3,229	1,611	9,881	—	—	11,492	8,087	1990	1997	(1)
7501 Boston Boulevard, Building Seven	Office	Springfield, VA	—	665	9,273	311	665	9,584	—	—	10,249	5,257	1997	1997	(1)

Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

				Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances	Land	Building
7435 Boston Boulevard, Building One	Office	Springfield, VA	—	392	3,822	4,290	486	8,018	—	—	8,504	6,162	1982	1997	(1)
7450 Boston Boulevard, Building Three	Office	Springfield, VA	—	1,165	4,681	2,177	1,327	6,696	—	—	8,023	3,462	1987	1998	(1)
32 Hartwell Avenue	Office	Lexington, MA	—	168	1,943	5,529	168	7,472	—	—	7,640	1,819	1968/1979/1987	1997	(1)
250 Binney Street	Office	Cambridge, MA	—	110	4,483	2,939	110	7,422	—	—	7,532	5,660	1983	1997	(1)
8000 Grainger Court, Building Five	Office	Springfield, VA	—	366	4,282	2,604	453	6,799	—	—	7,252	5,597	1984	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—	5,477	1,090	676	5,477	1,766	—	—	7,243	690	1977	2012	(1)
7300 Boston Boulevard, Building Thirteen	Office	Springfield, VA	—	608	4,773	795	608	5,568	—	—	6,176	1,928	2002	1997	(1)
17 Hartwell Avenue	Office	Lexington, MA	—	26	150	5,907	26	6,057	—	—	6,083	1,924	1968	1997	(1)
7601 Boston Boulevard, Building Eight	Office	Springfield, VA	—	200	878	4,367	378	5,067	—	—	5,445	4,507	1986	1997	(1)
7500 Boston Boulevard, Building Six	Office	Springfield, VA	—	138	3,749	1,107	234	4,760	—	—	4,994	4,097	1985	1997	(1)
8000 Corporate Court, Building Eleven	Office	Springfield, VA	—	136	3,071	1,245	686	3,766	—	—	4,452	3,094	1989	1997	(1)
7375 Boston Boulevard, Building Ten	Office	Springfield, VA	—	23	2,685	851	47	3,512	—	—	3,559	2,562	1988	1997	(1)
7374 Boston Boulevard, Building Four	Office	Springfield, VA	—	241	1,605	1,445	303	2,988	—	—	3,291	2,681	1984	1997	(1)
7451 Boston Boulevard, Building Two	Office	Springfield, VA	—	249	1,542	1,354	535	2,610	—	—	3,145	2,526	1982	1997	(1)
Signature at Reston	Residential	Reston, VA	—	27,076	190,580	393	27,076	190,973	—	—	218,049	8,773	2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—	9,243	127,248	2,939	9,245	130,185	—	—	139,430	4,566	2018	2015	(1)
The Avant at Reston Town Center	Residential	Reston, VA	—	20,350	91,995	830	20,350	92,825	—	—	113,175	14,728	2014	2010	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—	3,529	54,891	1,897	3,529	56,788	—	—	60,317	12,639	2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—	478	37,918	32,922	478	70,840	—	—	71,318	45,842	1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—	—	35,035	6,915	—	41,950	—	—	41,950	13,404	1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—	1,256	15,697	840	1,256	16,537	—	—	17,793	5,847	2006	2004	(1)
Kendall Center Blue Garage	Garage	Cambridge, MA	—	1,163	11,633	486	1,163	12,119	—	—	13,282	9,290	1990	1997	(1)
The Skylyne (MacArthur Station Residences)	Development	Oakland, CA	—	—	—	226,526	29,807	—	—	196,719	226,526	—	N/A	N/A	N/A
2100 Pennsylvania Avenue	Development	Washington, DC	—	—	—	224,380	185,129	—	—	39,251	224,380	1,024	N/A	N/A	N/A
Reston Gateway	Development	Reston, VA	—	—	—	150,632	—	—	—	150,632	150,632	—	N/A	1998	N/A
17Fifty Presidents Street	Development	Reston, VA	—	—	—	99,816	—	—	—	99,816	99,816	—	N/A	2013	N/A
20 CityPoint	Development	Waltham, MA	—	4,721	52,039	20,007	4,721	52,039	—	20,007	76,767	1,136	N/A	2007	N/A
325 Main Street	Development	Cambridge, MA	—	174	—	68,710	772	—	—	68,112	68,884	—	N/A	1997	N/A
North First Master Plan	Land	San Jose, CA	—	35,004	—	3,932	—	—	38,936	—	38,936	—	N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—	—	—	34,889	—	—	34,889	—	34,889	—	N/A	2006	N/A

Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

							Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements				Building and Improvements				Land Held for Development				Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances				Land		Building
425 Fourth Street	Land	San Francisco, CA	—				—		—		22,074		—				—				22,074				—		22,074		—		N/A	N/A	N/A
Springfield Metro Center	Land	Springfield, VA	—				—		—		19,844		—				—				19,844				—		19,844		—		N/A	2007	N/A
Reston Gateway Master Plan	Land	Reston, VA	—				—		—		18,292		—				—				18,292				—		18,292		—		N/A	1998	N/A
214 Third Avenue	Land	Waltham, MA	—				—		—		17,692		—				—				17,692				—		17,692		—		N/A	2006	N/A
103 Fourth Avenue	Land	Waltham, MA	—				—		—		12,826		—				—				12,826				—		12,826		—		N/A	2007	N/A
Crane Meadow	Land	Marlborough, MA	—				—		—		8,866		—				—				8,866				—		8,866		—		N/A	2000	N/A
Broad Run Business Park	Land	Loudoun County, VA	—				—		—		2,396		—				—				2,396				—		2,396		—		N/A	1998	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—				—		—		1,693		—				—				1,693				—		1,693		—		N/A	1997	N/A
Weston Quarry	Land	Weston, MA	—				—		—		1,249		—				—				1,249				—		1,249		—		N/A	2001	N/A
Reston Overlook Master Plan	Land	Reston, VA	—				—		—		39		—				—				39				—		39		—		N/A	2000	N/A

			$	2,922,408	(2	)	$	5,024,060	$	13,057,336	$	4,368,080	$	5,373,884	(3	)	$	16,031,028	(4	)	$	254,828	(5	)	$	789,736	$	22,449,476	$	5,135,289

The aggregate cost and accumulated depreciation for tax purposes was approximately $20.7 billion and $4.5 billion, respectively.


(1)	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.


(2)	Includes unamortized deferred financing costs totaling approximately $(26.7) million.


(3)	Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $214,091 and $148,640, respectively.


(4)	Includes Right of Use Assets - Finance Leases of approximately $23,303.

(5)

Includes pre-development costs.

Boston Properties Limited Partnership

Real Estate and Accumulated Depreciation

December 31, 2019, 2018 and 2017

(dollars in thousands)

A summary of activity for real estate and accumulated depreciation is as follows:



	2019			2018			2017
Real Estate:
Balance at the beginning of the year	$	21,207,189		$	20,647,236		$	19,701,185
Additions to/improvements of real estate	1,671,898			1,043,379			1,099,286
Assets sold/written-off	(429,611		)	(483,426		)	(153,235		)
Balance at the end of the year	$	22,449,476		$	21,207,189		$	20,647,236
Accumulated Depreciation:
Balance at the beginning of the year	$	4,773,800		$	4,473,895		$	4,116,020
Depreciation expense	557,130			525,584			488,919
Assets sold/written-off	(195,641		)	(225,679		)	(131,044		)
Balance at the end of the year	$	5,135,289		$	4,773,800		$	4,473,895

Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

Real Estate and Accumulated Depreciation Activity of Real Estate and Accumulated Depreciation (Notes)

12 Months Ended

Dec. 31, 2019

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Text Block]

Item 15. Exhibits and Financial Statement Schedules

(a) Financial Statement Schedule

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances		Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

					Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,274,028	$	1,796,252	$	1,532,654	$	202,612	$	1,796,252	$	1,735,266	$	—	$	—	$	3,531,518	$	313,158	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—		92,077		948,357		556,458		115,638		1,478,578		2,676		—		1,596,892		596,740		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—		179,697		847,410		415,228		195,987		1,246,348		—		—		1,442,335		633,711		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—		339,200		700,358		300,519		354,107		985,970		—		—		1,340,077		358,960		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	644,778		241,600		494,782		454,902		289,639		688,550		—		213,095		1,191,284		289,482		1977/1997	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—		200,349		946,205		—		200,349		946,205		—		—		1,146,554		38,727		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—		219,543		667,884		210,160		250,134		829,529		17,924		—		1,097,587		214,533		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—		285,263		603,167		51,928		285,263		655,095		—		—		940,358		116,857		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—		131,067		435,954		102,984		131,067		538,938		—		—		670,005		122,799		1971-1975/2017	2012	(1)
Times Square Tower	Office	New York, NY	—		165,413		380,438		113,222		169,193		489,880		—		—		659,073		217,303		2004	2000	(1)
Carnegie Center	Office	Princeton, NJ	—		142,666		316,856		152,280		94,240		462,882		54,680		—		611,802		208,331		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Atlantic Wharf	Office	Boston, MA	—		63,988		454,537		18,709		63,988		473,246		—		—		537,234		131,828		2011	2007	(1)
510 Madison Avenue	Office	New York, NY	—		103,000		253,665		25,495		103,000		279,160		—		—		382,160		72,213		2012	2010	(1)
Fountain Square	Office	Reston, VA	—		56,853		306,298		12,140		56,853		318,438		—		—		375,291		78,498		1986-1990	2012	(1)
599 Lexington Avenue	Office	New York, NY	—		81,040		100,507		188,572		87,852		282,267		—		—		370,119		183,291		1986	1997	(1)
680 Folsom Street	Office	San Francisco, CA	—		72,545		219,766		7,907		72,545		227,673		—		—		300,218		46,777		2014	2012	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—		—		183,541		113,627		109,038		188,130		—		—		297,168		59,190		2011	2008	(1)
145 Broadway	Office	Cambridge, MA	—		121		273,013		23,246		23,367		273,013		—		—		296,380		1,511		2019	1997	(1)
South of Market and Democracy Tower	Office	Reston, VA	—		13,603		237,479		26,415		13,687		263,810		—		—		277,497		99,478		2008-2009	2003	(1)
601 Massachusetts Avenue	Office	Washington, DC	—		95,310		165,173		3,945		95,322		169,106		—		—		264,428		24,502		2016	2008	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—		18,789		148,451		80,077		18,789		228,528		—		—		247,317		79,824		1985-1989	2011	(1)
Gateway Center	Office	San Francisco, CA	—		28,255		139,245		61,791		30,627		198,664		—		—		229,291		106,680		1984/1986/2002	1999	(1)
535 Mission Street	Office	San Francisco, CA	—		40,933		148,378		3,276		40,933		151,654		—		—		192,587		26,293		2015	2013	(1)
Reservoir Place	Office	Waltham, MA	—		18,605		104,124		53,718		20,108		156,339		—		—		176,447		70,870		1955/1987/2017	1997/1998	(1)
Mountain View Research Park	Office	Mountain View, CA	—		95,066		68,373		12,704		95,066		81,077		—		—		176,143		19,807		1977-1981/2007-2013	2013	(1)
1330 Connecticut Avenue	Office	Washington, DC	—		25,982		82,311		36,847		27,135		118,005		—		—		145,140		32,775		1984/2018	2004	(1)

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances	Original		Costs Capitalized Subsequent to Acquisition		Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

				Land	Building
Kingstowne Towne Center	Office	Alexandria, VA	—	18,021	109,038	3,376		18,062	112,373	—	—	130,435	44,294	2003-2006	2007	(1)
One Freedom Square	Office	Reston, VA	—	9,929	84,504	34,372		11,293	117,512	—	—	128,805	59,006	2000	2003	(1)
Capital Gallery	Office	Washington, DC	—	4,725	29,565	88,704		8,662	114,332	—	—	122,994	71,631	1981/2006	2007	(1)
Weston Corporate Center	Office	Weston, MA	—	25,753	92,312	(123	)	25,854	92,088	—	—	117,942	29,227	2010	2001	(1)
Two Freedom Square	Office	Reston, VA	—	13,930	77,739	23,209		15,420	99,458	—	—	114,878	50,668	2001	2003	(1)
One and Two Reston Overlook	Office	Reston, VA	—	16,456	66,192	24,181		16,179	90,650	—	—	106,829	51,503	1999	2000	(1)
Discovery Square	Office	Reston, VA	—	11,198	71,782	20,905		12,533	91,352	—	—	103,885	43,619	2001	2003	(1)
140 Kendrick Street	Office	Needham, MA	—	18,095	66,905	17,574		19,092	83,482	—	—	102,574	35,721	2000	2004	(1)
355 Main Street	Office	Cambridge, MA	—	18,863	53,346	27,582		21,173	78,618	—	—	99,791	26,439	1981/1996/2013	2006	(1)
880 & 890 Winter Street	Office	Waltham, MA	—	29,510	65,812	—		29,510	65,812	—	—	95,322	1,458	1998-1999	2019	(1)
10 CityPoint	Office	Waltham, MA	—	1,953	85,752	4,697		2,290	90,112	—	—	92,402	10,928	2016	1997	(1)
90 Broadway	Office	Cambridge, MA	—	19,104	52,078	19,857		20,785	70,254	—	—	91,039	23,621	1983/1998/2013	2006	(1)
230 CityPoint	Office	Waltham, MA	—	13,189	49,823	22,057		13,807	71,262	—	—	85,069	29,255	1992	2005	(1)
77 CityPoint	Office	Waltham, MA	—	13,847	60,383	10,556		14,023	70,763	—	—	84,786	27,172	2008	2001	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—	10,385	60,694	13,165		11,097	73,147	—	—	84,244	35,567	2003	1999	(1)
3625-3635 Peterson Way	Office	Santa Clara, CA	—	63,206	14,879	752		63,206	14,879	752	—	78,837	11,172	1979	2016	(1)
2440 West El Camino Real	Office	Mountain View, CA	—	16,741	51,285	5,454		16,741	56,739	—	—	73,480	13,090	1987/2003	2011	(1)
191 Spring Street	Office	Lexington, MA	—	2,850	59,751	7,695		3,151	67,145	—	—	70,296	21,917	1971/1995/2018	1997	(1)
300 Binney Street	Office	Cambridge, MA	—	18,080	51,262	140		18,080	51,402	—	—	69,482	11,146	2013	2009	(1)
Wisconsin Place	Office	Chevy Chase, MD	—	—	53,349	14,924		—	68,273	—	—	68,273	25,934	2009	2004	(1)
Reston Corporate Center	Office	Reston, VA	—	9,135	50,857	6,236		10,148	56,080	—	—	66,228	29,860	1984	1998	(1)
New Dominion Technology Park, Bldg. Two	Office	Herndon, VA	—	5,584	51,868	4,157		6,510	55,099	—	—	61,609	26,894	2004	1998	(1)
255 Main Street	Office	Cambridge, MA	—	134	25,110	34,124		548	58,820	—	—	59,368	33,543	1987	1997	(1)
University Place	Office	Cambridge, MA	3,602	—	37,091	16,001		7,418	45,674	—	—	53,092	29,423	1985	1998	(1)
New Dominion Technology Park, Bldg. One	Office	Herndon, VA	—	3,880	43,227	3,927		4,583	46,451	—	—	51,034	29,141	2001	1998	(1)
Sumner Square	Office	Washington, DC	—	624	28,745	21,344		3,535	47,178	—	—	50,713	27,093	1985	1999	(1)
200 West Street	Office	Waltham, MA	—	16,148	24,983	8,211		16,813	30,425	—	2,104	49,342	17,001	1999	1997	(1)
North First Business Park	Office	San Jose, CA	—	23,398	13,069	4,571		23,377	17,661	—	—	41,038	16,411	1981	2007	(1)
150 Broadway	Office	Cambridge, MA	—	850	25,042	8,540		1,323	33,109	—	—	34,432	19,875	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—	1,299	12,943	11,406		2,395	23,253	—	—	25,648	11,870	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—	998	1,426	18,547		1,264	19,707	—	—	20,971	14,312	1982	1997	(1)
201 Spring Street	Office	Lexington, MA	—	2,849	15,303	1,172		3,124	16,200	—	—	19,324	8,587	1997	1997	(1)
The Point	Office	Waltham, MA	—	6,395	10,040	421		6,492	10,364	—	—	16,856	1,349	2015	2007	(1)
33 Hayden Avenue	Office	Lexington, MA	—	266	3,234	12,898		425	15,973	—	—	16,398	5,678	1979	1997	(1)
690 Folsom Street	Office	San Francisco, CA	—	3,219	11,038	1,157		3,219	12,195	—	—	15,414	2,284	2015	2012	(1)

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances	Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

				Land	Building
92-100 Hayden Avenue	Office	Lexington, MA	—	594	6,748	7,529	802	14,069	—	—	14,871	12,041	1985	1997	(1)
181 Spring Street	Office	Lexington, MA	—	1,066	9,520	2,177	1,160	11,603	—	—	12,763	5,597	1999	1997	(1)
195 West Street	Office	Waltham, MA	—	1,611	6,652	4,218	1,858	10,623	—	—	12,481	8,352	1990	1997	(1)
7501 Boston Boulevard, Building Seven	Office	Springfield, VA	—	665	9,273	816	791	9,963	—	—	10,754	5,393	1997	1997	(1)
7435 Boston Boulevard, Building One	Office	Springfield, VA	—	392	3,822	4,983	659	8,538	—	—	9,197	6,344	1982	1997	(1)
7450 Boston Boulevard, Building Three	Office	Springfield, VA	—	1,165	4,681	2,591	1,430	7,007	—	—	8,437	3,575	1987	1998	(1)
32 Hartwell Avenue	Office	Lexington, MA	—	168	1,943	6,115	314	7,912	—	—	8,226	1,975	1968/1979/1987	1997	(1)
250 Binney Street	Office	Cambridge, MA	—	110	4,483	3,593	273	7,913	—	—	8,186	5,829	1983	1997	(1)
8000 Grainger Court, Building Five	Office	Springfield, VA	—	366	4,282	3,198	601	7,245	—	—	7,846	5,752	1984	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—	5,477	1,090	676	5,477	1,766	—	—	7,243	690	1977	2012	(1)
7300 Boston Boulevard, Building Thirteen	Office	Springfield, VA	—	608	4,773	1,007	661	5,727	—	—	6,388	1,984	2002	1997	(1)
17 Hartwell Avenue	Office	Lexington, MA	—	26	150	6,064	65	6,175	—	—	6,240	1,966	1968	1997	(1)
7601 Boston Boulevard, Building Eight	Office	Springfield, VA	—	200	878	5,060	551	5,587	—	—	6,138	4,689	1986	1997	(1)
7500 Boston Boulevard, Building Six	Office	Springfield, VA	—	138	3,749	1,640	367	5,160	—	—	5,527	4,237	1985	1997	(1)
8000 Corporate Court, Building Eleven	Office	Springfield, VA	—	136	3,071	1,596	774	4,029	—	—	4,803	3,191	1989	1997	(1)
7375 Boston Boulevard, Building Ten	Office	Springfield, VA	—	23	2,685	1,032	93	3,647	—	—	3,740	2,606	1988	1997	(1)
7374 Boston Boulevard, Building Four	Office	Springfield, VA	—	241	1,605	1,828	398	3,276	—	—	3,674	2,779	1984	1997	(1)
7451 Boston Boulevard, Building Two	Office	Springfield, VA	—	249	1,542	1,667	613	2,845	—	—	3,458	2,610	1982	1997	(1)
Signature at Reston	Residential	Reston, VA	—	27,076	190,580	393	27,076	190,973	—	—	218,049	8,773	2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—	9,243	127,248	2,939	9,245	130,185	—	—	139,430	4,566	2018	2015	(1)
The Avant at Reston Town Center	Residential	Reston, VA	—	20,350	91,995	830	20,350	92,825	—	—	113,175	14,728	2014	2010	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—	3,529	54,891	1,897	3,529	56,788	—	—	60,317	12,639	2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—	478	37,918	35,813	1,201	73,008	—	—	74,209	46,605	1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—	—	35,035	7,329	103	42,261	—	—	42,364	13,512	1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—	1,256	15,697	1,552	1,434	17,071	—	—	18,505	6,031	2006	2004	(1)
Kendall Center Blue Garage	Garage	Cambridge, MA	—	1,163	11,633	2,151	1,579	13,368	—	—	14,947	9,728	1990	1997	(1)
The Skylyne (MacArthur Station Residences)	Development	Oakland, CA	—	—	—	226,526	29,807	—	—	196,719	226,526	—	N/A	N/A	N/A
2100 Pennsylvania Avenue	Development	Washington, DC	—	—	—	224,380	185,129	—	—	39,251	224,380	1,024	N/A	N/A	N/A
Reston Gateway	Development	Reston, VA	—	—	—	150,632	—	—	—	150,632	150,632	—	N/A	1998	N/A
17Fifty Presidents Street	Development	Reston, VA	—	—	—	99,816	—	—	—	99,816	99,816	—	N/A	2013	N/A

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances				Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements				Building and Improvements				Land Held for Development				Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

							Land		Building
20 CityPoint	Development	Waltham, MA	—				4,721		52,039		20,007		4,721				52,039				—				20,007		76,767		1,136		N/A	2007	N/A
325 Main Street	Development	Cambridge, MA	—				174		—		68,903		965				—				—				68,112		69,077		—		N/A	1997	N/A
North First Master Plan	Land	San Jose, CA	—				35,004		—		3,932		—				—				38,936				—		38,936		—		N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—				—		—		34,889		—				—				34,889				—		34,889		—		N/A	2006	N/A
425 Fourth Street	Land	San Francisco, CA	—				—		—		22,074		—				—				22,074				—		22,074		—		N/A	N/A	N/A
Springfield Metro Center	Land	Springfield, VA	—				—		—		19,844		—				—				19,844				—		19,844		—		N/A	2007	N/A
Reston Gateway Master Plan	Land	Reston, VA	—				—		—		18,292		—				—				18,292				—		18,292		—		N/A	1998	N/A
214 Third Avenue	Land	Waltham, MA	—				—		—		17,692		—				—				17,692				—		17,692		—		N/A	2006	N/A
103 Fourth Avenue	Land	Waltham, MA	—				—		—		12,826		—				—				12,826				—		12,826		—		N/A	2007	N/A
Crane Meadow	Land	Marlborough, MA	—				—		—		8,866		—				—				8,866				—		8,866		—		N/A	2000	N/A
Broad Run Business Park	Land	Loudoun County, VA	—				—		—		2,396		—				—				2,396				—		2,396		—		N/A	1998	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—				—		—		1,693		—				—				1,693				—		1,693		—		N/A	1997	N/A
Weston Quarry	Land	Weston, MA	—				—		—		1,249		—				—				1,249				—		1,249		—		N/A	2001	N/A
Reston Overlook Master Plan	Land	Reston, VA	—				—		—		39		—				—				39				—		39		—		N/A	2000	N/A

			$	2,922,408	(2	)	$	5,024,060	$	13,057,336	$	4,763,301	$	5,474,337	(3	)	$	16,325,796	(4	)	$	254,828	(5	)	$	789,736	$	22,844,697	$	5,239,179

The aggregate cost and accumulated depreciation for tax purposes was approximately $18.6 billion and $4.0 billion, respectively.


(1)	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.


(2)	Includes unamortized deferred financing costs totaling approximately $(26.7) million.


(3)	Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $214,091 and $148,640, respectively.


(4)	Includes Right of Use Assets - Finance Leases of approximately $23,303.

(5)

Includes pre-development costs.

Boston Properties, Inc.

Real Estate and Accumulated Depreciation

December 31, 2019, 2018 and 2017

(dollars in thousands)

A summary of activity for real estate and accumulated depreciation is as follows:



	2019			2018			2017
Real Estate:
Balance at the beginning of the year	$	21,605,545		$	21,058,714		$	20,114,576
Additions to/improvements of real estate	1,671,898			1,043,379			1,099,286
Assets sold/written-off	(432,746		)	(496,548		)	(155,148		)
Balance at the end of the year	$	22,844,697		$	21,605,545		$	21,058,714
Accumulated Depreciation:
Balance at the beginning of the year	$	4,871,102		$	4,566,570		$	4,201,891
Depreciation expense	564,938			533,342			497,059
Assets sold/written-off	(196,861		)	(228,810		)	(132,380		)
Balance at the end of the year	$	5,239,179		$	4,871,102		$	4,566,570

Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

Organization (Policies)	12 Months Ended
Organization (Policies)	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements are presented using the accrual basis of accounting in conformity with accounting principles generally accepted in the United States of America. Boston Properties, Inc. does not have any other significant assets, liabilities or operations, other than its investment in Boston Properties Limited Partnership, nor does it have employees of its own. Boston Properties Limited Partnership, not Boston Properties, Inc., generally executes all significant business relationships other than transactions involving securities of Boston Properties, Inc. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income.
Variable Interest Entities (VIEs)	Variable Interest Entities (VIEs) Consolidated VIEs are those for which the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE.

Summary Of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Real Estate

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:



Land improvements		25 to 40 years
Buildings and improvements		10 to 40 years
Tenant improvements		Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment		3 to 7 years

Cash and Cash Equivalents

Cash Held in Escrows

Investments in Securities

Tenant and Other Receivables and Notes Receivables

Tenant and Other Receivables

Tenant and other accounts receivable, other than accrued rents receivable, are expected to be collected within one year.

Notes Receivable

Deferred Charges

Investments in Unconsolidated Joint Ventures

Revenue Recognition



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2020	$	5,440	$	10,673
2021	3,054		6,455
2022	357		5,699
2023	183		5,558
2024	135		4,043

Earnings Per Share and Earnings Per Common Unit

Earnings Per Share

Earnings Per Common Unit

Fair Value of Financial Instruments



	December 31, 2019				December 31, 2018
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable	$	80,000	$	81,931	$	80,000	$	80,000
Note receivable	15,920		14,978		19,468		19,468
Total	$	95,920	$	96,909	$	99,468	$	99,468

Mortgage notes payable, net	$	2,922,408	$	2,984,956	$	2,964,572	$	2,903,925
Unsecured senior notes, net	8,390,459		8,826,375		7,544,697		7,469,338
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	498,939		500,561		498,488		500,783
Total	$	11,811,806	$	12,311,892	$	11,007,757	$	10,874,046

Derivative Instruments and Hedging Activities

Stock-Based Employee Compensation Plans

Use of Estimates in the Preparation of Financial Statements

Lessee, Leases


•	the interpolated rates from yields on outstanding U.S. Treasury issuances for up to 30 years and for years 31 and beyond, longer-term publicly traded educational institution debt issued by high credit quality educational institutions with maturity dates up to 2116,


•	observable mortgage rates spread over U.S. Treasury issuances, and


•	unlevered property yields and discount rates.

The Company then applied adjustments to account for considerations related to term and interpolated the IBR.

Lessor, Leases

New Accounting Pronouncements

New Accounting Pronouncements Adopted

Leases

General Adoption

(1) the timing and pattern of transfer of the nonlease component(s) and associated lease components are the same; and

(2) the lease component, if accounted for separately, would be classified as an operating lease.

Lessee


•	the interpolated rates from yields on outstanding U.S. Treasury issuances for up to 30 years and for years 31 and beyond, longer-term publicly traded educational institution debt issued by high credit quality educational institutions with maturity dates up to 2116,


•	observable mortgage rates spread over U.S. Treasury issuances, and


•	unlevered property yields and discount rates.

The Company then applied adjustments to account for considerations related to term and interpolated the IBR.

The Company has four finance lease obligations with various initial term expiration dates through 2094, see Note 3.

The following table provides lease cost information for the Company’s operating and finance leases for the year ended December 31, 2019 (in thousands):



Lease costs
Operating lease costs	$	14,573
Finance lease costs
Amortization of right of use asset (1)	$	29
Interest on lease liabilities (2)	$	47

_______________

(1)


(2)	Three of the finance leases relate to assets under development and as such, the entire interest amount was capitalized.

The following table provides other quantitative information for the Company’s operating and finance leases as of December 31, 2019:



	December 31, 2019
Other information
Weighted-average remaining lease term (in years)
Operating leases	51
Finance leases	71
Weighted-average discount rate
Operating leases	5.7	%
Finance leases	6.2	%



Years Ending December 31,	(in thousands)
2019	$	11,425
2020	18,425
2021	25,310
2022	8,894
2023	9,084
Thereafter	567,232

The following table provides a maturity analysis for the Company’s future minimum lease payments, as of December 31, 2018, related to the four capital leases, through 2036:



Years Ending December 31,	(in thousands)
2019	$	1,441
2020	12,682
2021	2,123
2022	1,253
2023	944
Thereafter	73,241
Total expected minimum lease payments	91,684
Interest portion	(27,497		)
Present value of expected net minimum lease payments	$	64,187

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2019 (in thousands):



	Operating			Finance
2020	$	10,050		$	834
2021	24,973			5,960
2022	18,041			10,208
2023	10,322			9,708
2024 (1)	9,277			48,518
Thereafter	557,954			1,383,242
Total lease payments	630,617			1,458,470
Less: interest portion	(430,437		)	(1,234,428		)
Present value of lease payments	$	200,180		$	224,042

_______________


(1)	Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company is reasonably certain it will exercise.

Lessor

The following table summarizes the components of lease revenue recognized during the year ended December 31, 2019 included within the Company’s Consolidated Statements of Operations (in thousands):



Lease Revenue
Fixed contractual payments	$	2,261,260
Variable lease payments	496,754
	$	2,758,014

New Accounting Pronouncements Issued but not yet Adopted

Financial Instruments - Credit Losses

adoption of ASU 2016-13 and ASU 2018-19 did not have a material impact on the Company’s consolidated financial statements.

Fair Value Measurement

Derivatives and Hedging

Consolidation

Equity Offering Costs

Underwriting commissions and offering costs have been reflected as a reduction of additional paid-in capital.

Treasury Stock

Boston Properties, Inc.’s share repurchases are reflected as treasury stock utilizing the cost method of accounting and are presented as a reduction to consolidated stockholders’ equity.

Dividends

Income Taxes

Boston Properties Limited Partnership

Income Taxes

Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment [Table Text Block]

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:



Land improvements		25 to 40 years
Buildings and improvements		10 to 40 years
Tenant improvements		Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment		3 to 7 years

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2020	$	5,440	$	10,673
2021	3,054		6,455
2022	357		5,699
2023	183		5,558
2024	135		4,043

The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands).



	Acquired In-Place Lease Intangibles
2020	$	17,536
2021	11,001
2022	5,918
2023	4,286
2024	2,510

Fair Value, by Balance Sheet Grouping [Table Text Block]

The following table presents the aggregate carrying value of the Company’s related party note receivable, note receivable, mortgage notes payable, net, unsecured senior notes, net, unsecured line of credit and unsecured term loan, net and the Company’s corresponding estimate of fair value as of December 31, 2019 and December 31, 2018 (in thousands):



	December 31, 2019				December 31, 2018
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable	$	80,000	$	81,931	$	80,000	$	80,000
Note receivable	15,920		14,978		19,468		19,468
Total	$	95,920	$	96,909	$	99,468	$	99,468

Mortgage notes payable, net	$	2,922,408	$	2,984,956	$	2,964,572	$	2,903,925
Unsecured senior notes, net	8,390,459		8,826,375		7,544,697		7,469,338
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	498,939		500,561		498,488		500,783
Total	$	11,811,806	$	12,311,892	$	11,007,757	$	10,874,046

Lease, Cost [Table Text Block]

The following table provides lease cost information for the Company’s operating and finance leases for the year ended December 31, 2019 (in thousands):



Lease costs
Operating lease costs	$	14,573
Finance lease costs
Amortization of right of use asset (1)	$	29
Interest on lease liabilities (2)	$	47

_______________

(1)


(2)	Three of the finance leases relate to assets under development and as such, the entire interest amount was capitalized.

The following table provides other quantitative information for the Company’s operating and finance leases as of December 31, 2019:



	December 31, 2019
Other information
Weighted-average remaining lease term (in years)
Operating leases	51
Finance leases	71
Weighted-average discount rate
Operating leases	5.7	%
Finance leases	6.2	%

Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]



Years Ending December 31,	(in thousands)
2019	$	11,425
2020	18,425
2021	25,310
2022	8,894
2023	9,084
Thereafter	567,232

Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block]

The following table provides a maturity analysis for the Company’s future minimum lease payments, as of December 31, 2018, related to the four capital leases, through 2036:



Years Ending December 31,	(in thousands)
2019	$	1,441
2020	12,682
2021	2,123
2022	1,253
2023	944
Thereafter	73,241
Total expected minimum lease payments	91,684
Interest portion	(27,497		)
Present value of expected net minimum lease payments	$	64,187

Lessee, Operating and Finance Lease Liability [Table Text Block]

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2019 (in thousands):



	Operating			Finance
2020	$	10,050		$	834
2021	24,973			5,960
2022	18,041			10,208
2023	10,322			9,708
2024 (1)	9,277			48,518
Thereafter	557,954			1,383,242
Total lease payments	630,617			1,458,470
Less: interest portion	(430,437		)	(1,234,428		)
Present value of lease payments	$	200,180		$	224,042

_______________

(1)

Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company is reasonably certain it will exercise.

Operating Lease, Lease Income [Table Text Block]

The following table summarizes the components of lease revenue recognized during the year ended December 31, 2019 included within the Company’s Consolidated Statements of Operations (in thousands):



Lease Revenue
Fixed contractual payments	$	2,261,260
Variable lease payments	496,754
	$	2,758,014

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes, Table [Table Text Block]

The tax treatment of common dividends per share for federal income tax purposes is as follows:



	For the year ended December 31,
	2019					2018					2017
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	2.99		94.84	%	$	2.79		78.17	%	$	2.86		98.29	%
Capital gain income	0.16			5.16	%	0.78			21.83	%	0.05			1.71	%
Total	$	3.15	(1)	100.00	%	$	3.57	(2)	100.00	%	$	2.91	(3)	100.00	%

_____________


(1)	The fourth quarter 2019 regular quarterly dividend was $0.98 per common share of which approximately $0.04 per common share was allocable to 2019 and approximately $0.94 per common share is allocable to 2020.


(2)	The fourth quarter 2018 regular quarterly dividend was $0.95 per common share of which approximately $0.69 per common share was allocable to 2018 and approximately $0.26 per common share is allocable to 2019.

(3)

The fourth quarter 2017 regular quarterly dividend was $0.80 per common share of which approximately $0.47 per common share was allocable to 2017 and approximately $0.33 per common share is allocable to 2018.

The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per OP Unit and LTIP Unit paid or payable in 2019 and 2018:



Record Date	Payment Date	Dividend (Per Share)		Distribution (Per Unit)
December 31, 2019	January 30, 2020		$0.98		$0.98
September 30, 2019	October 31, 2019		$0.95		$0.95
June 28, 2019	July 31, 2019		$0.95		$0.95
March 29, 2019	April 30, 2019		$0.95		$0.95

December 31, 2018	January 30, 2019		$0.95		$0.95
September 28, 2018	October 31, 2018		$0.95		$0.95
June 29, 2018	July 31, 2018		$0.80		$0.80
March 29, 2018	April 30, 2018		$0.80		$0.80
December 29, 2017	January 30, 2018		$0.80		$0.80

Finance Lease, Liability, Maturity [Table Text Block]

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2019 (in thousands):



	Operating			Finance
2020	$	10,050		$	834
2021	24,973			5,960
2022	18,041			10,208
2023	10,322			9,708
2024 (1)	9,277			48,518
Thereafter	557,954			1,383,242
Total lease payments	630,617			1,458,470
Less: interest portion	(430,437		)	(1,234,428		)
Present value of lease payments	$	200,180		$	224,042

_______________

(1)

Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company is reasonably certain it will exercise.

Real Estate (Tables)

12 Months Ended

Aug. 27, 2019

Jul. 16, 2019

Jan. 24, 2019

Dec. 31, 2019

Schedule of Real Estate Properties

Boston Properties, Inc.

Real estate consisted of the following at December 31, 2019 and December 31, 2018 (in thousands):



	2019			2018
Land	$	5,111,606		$	5,072,568
Right of use assets - finance leases	237,394			—
Right of use assets - operating leases	148,640			—
Land held for future development (1)	254,828			200,498
Buildings and improvements	13,646,054			13,356,751
Tenant improvements	2,656,439			2,396,932
Furniture, fixtures and equipment	44,313			44,351
Construction in progress	789,736			578,796
Total	22,889,010			21,649,896
Less: Accumulated depreciation	(5,266,798		)	(4,897,777		)
	$	17,622,212		$	16,752,119

_______________

(1)

Includes pre-development costs.

Finance Lease, Liability, Maturity [Table Text Block]

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2019 (in thousands):



	Operating			Finance
2020	$	10,050		$	834
2021	24,973			5,960
2022	18,041			10,208
2023	10,322			9,708
2024 (1)	9,277			48,518
Thereafter	557,954			1,383,242
Total lease payments	630,617			1,458,470
Less: interest portion	(430,437		)	(1,234,428		)
Present value of lease payments	$	200,180		$	224,042

_______________

(1)

Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company is reasonably certain it will exercise.

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2020	$	5,440	$	10,673
2021	3,054		6,455
2022	357		5,699
2023	183		5,558
2024	135		4,043

The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands).



	Acquired In-Place Lease Intangibles
2020	$	17,536
2021	11,001
2022	5,918
2023	4,286
2024	2,510

880 & 890 Winter Street [Member]

Schedule of Business Acquisitions, by Acquisition [Table Text Block]

The following table summarizes the allocation of the purchase price, including transaction costs, of 880 and 890 Winter Street at the date of acquisition (in thousands):



Land	$	29,510
Building and improvements	59,788
Tenant improvements	6,024
In-place lease intangibles	11,494
Above-market lease intangibles	246
Below-market lease intangibles	(1,092		)
Net assets acquired	$	105,970

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]



	Acquired In-Place Lease Intangibles		Acquired Above-Market Lease Intangibles		Acquired Below- Market Lease Intangibles
Period from August 27, 2019 through December 31, 2019	$	1,801	$	28	$	(226	)
2020	4,485		80		(599		)
2021	2,391		80		(237		)
2022	1,121		43		(30		)
2023	179		15		—
2024	60		—		—

Finance Lease, Liability, Maturity [Table Text Block]

As of January 24, 2019, the lease payments from the finance lease related to the remaining parcels made available for lease to the Company were as follows (in thousands):



Period from January 24, 2019 through December 31, 2019	$	17,918
2020	109,460
Total expected minimum lease payments	127,378
Interest portion	(4,815		)
Present value of expected net lease payments	$	122,563

2100 Pennsylvania Avenue

Finance Lease, Liability, Maturity [Table Text Block]

As of July 16, 2019, the lease payments from the finance lease were as follows (in thousands):



Period from July 16, 2019 through December 31, 2019	$	—
2020	—
2021	3,863
2022	8,576
2023	8,669
Thereafter	1,358,518
Total expected minimum lease payments	1,379,626
Interest portion	(1,214,649		)
Present value of expected net lease payments	$	164,977

Schedule of Real Estate Properties

Boston Properties Limited Partnership

Real estate consisted of the following at December 31, 2019 and December 31, 2018 (in thousands):



	2019			2018
Land	$	5,011,153		$	4,971,475
Right of use assets - finance leases	237,394			—
Right of use assets - operating leases	148,640			—
Land held for future development (1)	254,828			200,498
Buildings and improvements	13,351,286			13,059,488
Tenant improvements	2,656,439			2,396,932
Furniture, fixtures and equipment	44,313			44,351
Construction in progress	789,736			578,796
Total	22,493,789			21,251,540
Less: Accumulated depreciation	(5,162,908		)	(4,800,475		)
	$	17,330,881		$	16,451,065

_______________

(1)

Includes pre-development costs.

Deferred Charges (Tables)

12 Months Ended

Dec. 31, 2019

Deferred Charges [Abstract]

Deferred Charges

Deferred charges consisted of the following at December 31, 2019 and December 31, 2018 (in thousands):



	2019			2018
Leasing costs, including lease related intangibles	$	1,155,958		$	1,191,297
Financing costs	12,728			12,796
	1,168,686			1,204,093
Less: Accumulated amortization	(479,473		)	(525,369		)
	$	689,213		$	678,724

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).



	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2020	$	5,440	$	10,673
2021	3,054		6,455
2022	357		5,699
2023	183		5,558
2024	135		4,043

The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands).



	Acquired In-Place Lease Intangibles
2020	$	17,536
2021	11,001
2022	5,918
2023	4,286
2024	2,510

Investments in Unconsolidated Joint Ventures (Tables)

12 Months Ended

Dec. 31, 2019

Schedule of Equity Method Investments [Line Items]

Investments In Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at December 31, 2019 and 2018:



					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			December 31, 2019			December 31, 2018
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.0	%		$	(4,872	)	$	(6,424	)
BP/CRF Metropolitan Square, LLC	Metropolitan Square	20.0	%		9,134			2,644
901 New York, LLC	901 New York Avenue	25.0	%	(2)	(12,113		)	(13,640		)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.3	%	(3)	36,789			38,214
Annapolis Junction NFM LLC	Annapolis Junction	50.0	%	(4)	25,391			25,268
540 Madison Venture LLC	540 Madison Avenue	60.0	%	(5)	2,953			66,391
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.0	%		(5,439		)	(5,026		)
501 K Street LLC	1001 6th Street	50.0	%	(6)	42,496			42,557
Podium Developer LLC	The Hub on Causeway - Podium	50.0	%		49,466			69,302
Residential Tower Developer LLC	Hub50House	50.0	%		55,092			47,505
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.0	%		9,883			3,022
Office Tower Developer LLC	100 Causeway Street	50.0	%		56,606			23,804
1265 Main Office JV LLC	1265 Main Street	50.0	%		3,780			3,918
BNY Tower Holdings LLC	Dock 72	50.0	%		94,804			82,520
BNYTA Amenity Operator LLC	Dock 72	50.0	%		—			N/A
CA-Colorado Center Limited Partnership	Colorado Center	50.0	%		252,069			253,495
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.0	%		56,247			69,724
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.0	%		67,499			46,993
SMBP Venture LP	Santa Monica Business Park	55.0	%		163,937			180,952
Platform 16 Holdings LP	Platform 16	55.0	%	(7)	29,501			N/A
					$	933,223		$	931,219

_______________


(1)	Investments with deficit balances aggregating approximately $22.4 million and $25.1 million at December 31, 2019 and 2018, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.


(2)	The Company’s economic ownership has increased based on the achievement of certain return thresholds.


(3)	The Company’s wholly-owned subsidiary that owns Wisconsin Place Office also owns a 33.3% interest in the joint venture entity that owns the land, parking garage and infrastructure of the project.


(4)	The joint venture owns three in-service buildings and two undeveloped land parcels.


(5)	The property was sold on June 27, 2019. As of December 31, 2019, the investment is comprised of undistributed cash. See note below for additional details.


(6)	Under the joint venture agreement for this land parcel, the partner will be entitled to up to two additional payments from the venture based on increases in total entitled square footage of the project above 520,000 square feet and achieving certain project returns at stabilization.

(7)

This entity is a VIE (See Note 1).

Schedule Of Balance Sheets Of The Unconsolidated Joint Ventures [Text Block]

The combined summarized balance sheets of the Company’s unconsolidated joint ventures are as follows:



	December 31, 2019		December 31, 2018
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	3,904,400	$	3,545,906
Other assets	502,706		543,512
Total assets	$	4,407,106	$	4,089,418
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	2,218,853	$	2,017,609
Other liabilities (2)	749,675		582,006
Members’/Partners’ equity	1,438,578		1,489,803
Total liabilities and members’/partners’ equity	$	4,407,106	$	4,089,418
Company’s share of equity	$	591,905	$	622,498
Basis differentials (3)	341,318		308,721
Carrying value of the Company’s investments in unconsolidated joint ventures (4)	$	933,223	$	931,219

_______________


(1)	At December 31, 2019, this amount includes right of use assets - finance leases and right of use assets - operating leases totaling approximately $383.9 million and $12.1 million, respectively.


(2)	At December 31, 2019, this amount includes lease liabilities - finance leases and lease liabilities - operating leases totaling approximately $510.8 million and $17.3 million, respectively.

(3)

(4)

Investments with deficit balances aggregating approximately $22.4 million and $25.1 million at December 31, 2019 and 2018, respectively, have been reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

Statements Of Operations Of The Joint Ventures

The combined summarized statements of operations of the Company’s unconsolidated joint ventures are as follows:



	For the year ended December 31,
	2019			2018			2017
	(in thousands)
Total revenue (1)	$	322,817		$	271,951		$	222,517
Expenses
Operating	122,992			106,610			90,542
Transaction costs	1,000			—			—
Depreciation and amortization (2)	102,296			103,079			57,079
Total expenses	226,288			209,689			147,621
Other income (expense)
Gains on sales of real estate (3)	32,706			16,951			—
Interest expense	(84,409		)	(71,308		)	(46,371		)
Net income	$	44,826		$	7,905		$	28,525

Company’s share of net income	$	24,423		$	8,084		$	18,439
Basis differential (3)(4)	22,169			(5,862		)	(7,207		)
Income from unconsolidated joint ventures	$	46,592		$	2,222		$	11,232

_______________


(1)	Includes straight-line rent adjustments of approximately $32.4 million, $15.9 million and $21.7 million for the years ended December 31, 2019, 2018 and 2017, respectively.


(2)	During the year ended December 31, 2018, the joint venture that owns Metropolitan Square in Washington, DC, commenced a renovation project and recorded accelerated depreciation expense of approximately $22.4 million related to the remaining book value of the assets to be replaced. The Company’s share of the accelerated depreciation expense totaled approximately $4.5 million.

(3)

(4)

Includes straight-line rent adjustments of approximately $2.1 million, $2.4 million and $1.9 million for the years ended December 31, 2019, 2018 and 2017, respectively. Also includes net above-/below-market rent adjustments of approximately $1.7 million, $1.6 million and $2.9 million for the years ended December 31, 2019, 2018 and 2017, respectively.

Mortgage Notes Payable, Net Schedule of Aggregate Principal Payments On Mortgage Notes (Tables)

12 Months Ended

Dec. 31, 2019

Mortgage Notes Payable [Abstract]

Schedule of Aggregate Principal Payments On Mortgage Notes [Table Text Block]

Contractual aggregate principal payments of mortgage notes payable at December 31, 2019 are as follows (in thousands):



	Principal Payments
2020	$	17,168
2021	17,276
2022	614,710
2023	—
2024	—
Thereafter	2,300,000
Total aggregate principal payments	2,949,154
Deferred financing costs, net	(26,746		)
Total carrying value of mortgage notes payable, net	$	2,922,408

Unsecured Senior Notes (Tables)

12 Months Ended

Dec. 31, 2019

Debt Disclosure [Abstract]

Schedule of Senior Notes

The following summarizes the unsecured senior notes outstanding as of December 31, 2019 (dollars in thousands):



	Coupon/ Stated Rate		Effective Rate(1)		Principal Amount			Maturity Date(2)
10 Year Unsecured Senior Notes	4.125	%	4.289	%	$	850,000		May 15, 2021
11 Year Unsecured Senior Notes	3.850	%	3.954	%	1,000,000			February 1, 2023
10.5 Year Unsecured Senior Notes	3.125	%	3.279	%	500,000			September 1, 2023
10.5 Year Unsecured Senior Notes	3.800	%	3.916	%	700,000			February 1, 2024
7 Year Unsecured Senior Notes	3.200	%	3.350	%	850,000			January 15, 2025
10 Year Unsecured Senior Notes	3.650	%	3.766	%	1,000,000			February 1, 2026
10 Year Unsecured Senior Notes	2.750	%	3.495	%	1,000,000			October 1, 2026
10 Year Unsecured Senior Notes	4.500	%	4.628	%	1,000,000			December 1, 2028
10 Year Unsecured Senior Notes	3.400	%	3.505	%	850,000			June 21, 2029
10.5 Year Unsecured Senior Notes	2.900	%	2.984	%	700,000			March 15, 2030
Total principal					8,450,000
Net unamortized discount					(17,451		)
Deferred financing costs, net					(42,090		)
Total					$	8,390,459

_______________


(1)	Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.

(2)

No principal amounts are due prior to maturity.

Noncontrolling Interest [Line Items]

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

Noncontrolling Interests (Tables)

12 Months Ended

Dec. 31, 2019

Distribution Declared to OP, LTIP, OPP and MYLTIP Units [Table Text Block]

The tax treatment of common dividends per share for federal income tax purposes is as follows:



	For the year ended December 31,
	2019					2018					2017
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	2.99		94.84	%	$	2.79		78.17	%	$	2.86		98.29	%
Capital gain income	0.16			5.16	%	0.78			21.83	%	0.05			1.71	%
Total	$	3.15	(1)	100.00	%	$	3.57	(2)	100.00	%	$	2.91	(3)	100.00	%

_____________


(1)	The fourth quarter 2019 regular quarterly dividend was $0.98 per common share of which approximately $0.04 per common share was allocable to 2019 and approximately $0.94 per common share is allocable to 2020.


(2)	The fourth quarter 2018 regular quarterly dividend was $0.95 per common share of which approximately $0.69 per common share was allocable to 2018 and approximately $0.26 per common share is allocable to 2019.

(3)

The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per OP Unit and LTIP Unit paid or payable in 2019 and 2018:



Record Date	Payment Date	Dividend (Per Share)		Distribution (Per Unit)
December 31, 2019	January 30, 2020		$0.98		$0.98
September 30, 2019	October 31, 2019		$0.95		$0.95
June 28, 2019	July 31, 2019		$0.95		$0.95
March 29, 2019	April 30, 2019		$0.95		$0.95

December 31, 2018	January 30, 2019		$0.95		$0.95
September 28, 2018	October 31, 2018		$0.95		$0.95
June 29, 2018	July 31, 2018		$0.80		$0.80
March 29, 2018	April 30, 2018		$0.80		$0.80
December 29, 2017	January 30, 2018		$0.80		$0.80

Noncontrolling Interests [Member]

Noncontrolling Interest [Line Items]

Distribution Declared to OP, LTIP, OPP and MYLTIP Units [Table Text Block]



Record Date	Payment Date	Distributions per OP Unit and LTIP Unit		Distributions per MYLTIP Unit
December 31, 2019	January 30, 2020		$0.98		$0.098
September 30, 2019	October 31, 2019		$0.95		$0.095
June 28, 2019	July 31, 2019		$0.95		$0.095
March 29, 2019	April 30, 2019		$0.95		$0.095
December 31, 2018	January 30, 2019		$0.95		$0.095

The following table presents Boston Properties Limited Partnership’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units, 2013 MYLTIP Units, 2014 MYLTIP Units and, after the February 4, 2018 measurement date, the 2015 MYLTIP Units) and its distributions on the 2015 MYLTIP Units (prior to the February 4, 2018 measurement date), 2016 MYLTIP Units, 2017 MYLTIP Units and 2018 MYLTIP Units (after the February 6, 2018 issuance date) that occurred during the year ended December 31, 2018:



Record Date	Payment Date	Distributions per OP Unit and LTIP Unit		Distributions per MYLTIP Unit
December 31, 2018	January 30, 2019		$0.95		$0.095
September 28, 2018	October 31, 2018		$0.95		$0.095
June 29, 2018	July 31, 2018		$0.80		$0.080
March 29, 2018	April 30, 2018		$0.80		$0.080
December 29, 2017	January 30, 2018		$0.80		$0.080

Stockholders' Equity / Partners' Capital (Tables)

12 Months Ended

Dec. 31, 2019

Class of Stock [Line Items]

Dividends Declared [Table Text Block]

The tax treatment of common dividends per share for federal income tax purposes is as follows:



	For the year ended December 31,
	2019					2018					2017
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	2.99		94.84	%	$	2.79		78.17	%	$	2.86		98.29	%
Capital gain income	0.16			5.16	%	0.78			21.83	%	0.05			1.71	%
Total	$	3.15	(1)	100.00	%	$	3.57	(2)	100.00	%	$	2.91	(3)	100.00	%

_____________


(1)	The fourth quarter 2019 regular quarterly dividend was $0.98 per common share of which approximately $0.04 per common share was allocable to 2019 and approximately $0.94 per common share is allocable to 2020.


(2)	The fourth quarter 2018 regular quarterly dividend was $0.95 per common share of which approximately $0.69 per common share was allocable to 2018 and approximately $0.26 per common share is allocable to 2019.

(3)

The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per OP Unit and LTIP Unit paid or payable in 2019 and 2018:



Record Date	Payment Date	Dividend (Per Share)		Distribution (Per Unit)
December 31, 2019	January 30, 2020		$0.98		$0.98
September 30, 2019	October 31, 2019		$0.95		$0.95
June 28, 2019	July 31, 2019		$0.95		$0.95
March 29, 2019	April 30, 2019		$0.95		$0.95

December 31, 2018	January 30, 2019		$0.95		$0.95
September 28, 2018	October 31, 2018		$0.95		$0.95
June 29, 2018	July 31, 2018		$0.80		$0.80
March 29, 2018	April 30, 2018		$0.80		$0.80
December 29, 2017	January 30, 2018		$0.80		$0.80

Series B Preferred Stock [Member]

Class of Stock [Line Items]

Dividends Declared [Table Text Block]

The following table presents Boston Properties Inc.’s dividends per share on its outstanding Series B Preferred Stock paid or payable in 2019 and 2018:



Record Date	Payment Date	Dividend (Per Share)
February 4, 2020	February 18, 2020		$32.8125
November 1, 2019	November 15, 2019		$32.8125
August 2, 2019	August 15, 2019		$32.8125
May 3, 2019	May 15, 2019		$32.8125

February 4, 2019	February 15, 2019		$32.8125
November 2, 2018	November 15, 2018		$32.8125
August 3, 2018	August 15, 2018		$32.8125
May 4, 2018	May 15, 2018		$32.8125
February 2, 2018	February 15, 2018		$32.8125

Future Minimum Rents (Tables)

12 Months Ended

Dec. 31, 2019

Future Minimum Rents [Abstract]

Lessor, Operating Lease, Payments to be Received, Maturity Table [Table Text Block]



Years Ending December 31,	(in thousands)
2019	$	2,088,171
2020	2,106,963
2021	2,015,031
2022	1,838,699
2023	1,736,636
Thereafter	12,295,464



Years Ending December 31,	(in thousands)
2020	$	2,205,675
2021	2,222,643
2022	2,126,968
2023	2,068,871
2024	1,974,144
Thereafter	13,892,504

Segment Information (Tables)

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Schedule Of Reconciliation Of Net Operating Income To Net Income

Boston Properties, Inc.



	Year ended December 31,
	2019		2018			2017
	(in thousands)
Net income attributable to Boston Properties, Inc. common shareholders	$	511,034	$	572,347		$	451,939
Add:
Preferred dividends	10,500		10,500			10,500
Noncontrolling interest—common units of the Operating Partnership	59,345		66,807			52,210
Noncontrolling interests in property partnerships	71,120		62,909			47,832
Interest expense	412,717		378,168			374,481
Losses (gains) from early extinguishments of debt	29,540		16,490			(496		)
Impairment losses	24,038		11,812			—
Net operating income from unconsolidated joint ventures	97,716		79,893			64,008
Depreciation and amortization expense	677,764		645,649			617,547
Transaction costs	1,984		1,604			668
Payroll and related costs from management services contracts	10,386		9,590			—
General and administrative expense	140,777		121,722			113,715
Less:
Net operating income attributable to noncontrolling interests in property partnerships	183,989		177,365			174,245
Gains (losses) from investments in securities	6,417		(1,865		)	3,678
Interest and other income	18,939		10,823			5,783
Gains on sales of real estate	709		182,356			7,663
Income from unconsolidated joint ventures	46,592		2,222			11,232
Direct reimbursements of payroll and related costs from management services contracts	10,386		9,590			—
Development and management services revenue	40,039		45,158			34,605
Company’s share of Net Operating Income	$	1,739,850	$	1,551,842		$	1,495,198

Boston Properties Limited Partnership



	Year ended December 31,
		2019		2018			2017
		(in thousands)
Net income attributable to Boston Properties Limited Partnership common unitholders		$	580,102	$	656,903		$	512,866
Add:
Preferred distributions		10,500		10,500			10,500
Noncontrolling interests in property partnerships		71,120		62,909			47,832
Interest expense		412,717		378,168			374,481
Losses (gains) from early extinguishments of debt		29,540		16,490			(496		)
Impairment losses		22,272		10,181			—
Net operating income from unconsolidated joint ventures		97,716		79,893			64,008
Depreciation and amortization expense		669,956		637,891			609,407
Transaction costs		1,984		1,604			668
Payroll and related costs from management services contracts		10,386		9,590			—
General and administrative expense		140,777		121,722			113,715
Less:
Net operating income attributable to noncontrolling interests in property partnerships		183,989		177,365			174,245
Gains (losses) from investments in securities		6,417		(1,865		)	3,678
Interest and other income		18,939		10,823			5,783
Gains on sales of real estate		858		190,716			8,240
Income from unconsolidated joint ventures		46,592		2,222			11,232
Direct reimbursements of payroll and related costs from management services contracts		10,386		9,590			—
Development and management services revenue		40,039		45,158			34,605
Company’s share of Net Operating Income		$	1,739,850	$	1,551,842		$	1,495,198

Schedule Of Segment Information By Geographic Area And Property Type

Information by geographic area and property type (dollars in thousands):

For the year ended December 31, 2019:



	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	895,098		$	—		$	1,011,912		$	533,189		$	384,435		$	2,824,634
Residential	13,786			—			—			—			23,128			36,914
Hotel	48,589			—			—			—			—			48,589
Total	957,473			—			1,011,912			533,189			407,563			2,910,137
% of Grand Totals	32.90		%	—		%	34.78		%	18.32		%	14.00		%	100.00		%
Rental Expenses:
Office	322,282			—			389,532			177,994			144,217			1,034,025
Residential	5,071			—			—			—			10,914			15,985
Hotel	34,004			—			—			—			—			34,004
Total	361,357			—			389,532			177,994			155,131			1,084,014
% of Grand Totals	33.34		%	—		%	35.93		%	16.42		%	14.31		%	100.00		%
Net operating income	$	596,116		$	—		$	622,380		$	355,195		$	252,432		$	1,826,123
% of Grand Totals	32.64		%	—		%	34.09		%	19.45		%	13.82		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(40,109		)	—			(143,432		)	(448		)	—			(183,989		)
Add: Company’s share of net operating income from unconsolidated joint ventures	5,494			61,338			4,174			—			26,710			97,716
Company’s share of net operating income	$	561,501		$	61,338		$	483,122		$	354,747		$	279,142		$	1,739,850
% of Grand Totals	32.27		%	3.53		%	27.77		%	20.39		%	16.04		%	100.00		%

_______________


(1)	Rental Revenue is equal to Total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

For the year ended December 31, 2018:



	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	838,341		$	—		$	959,050		$	397,180		$	396,088		$	2,590,659
Residential	6,694			—			—			—			15,857			22,551
Hotel	49,118			—			—			—			—			49,118
Total	894,153			—			959,050			397,180			411,945			2,662,328
% of Grand Totals	33.59		%	—		%	36.02		%	14.92		%	15.47		%	100.00		%
Rental Expenses:
Office	315,653			—			377,992			130,016			142,886			966,547
Residential	3,632			—			—			—			8,972			12,604
Hotel	33,863			—			—			—			—			33,863
Total	353,148			—			377,992			130,016			151,858			1,013,014
% of Grand Totals	34.86		%	—		%	37.32		%	12.83		%	14.99		%	100.00		%
Net operating income	$	541,005		$	—		$	581,058		$	267,164		$	260,087		$	1,649,314
% of Grand Totals	32.80		%	—		%	35.23		%	16.20		%	15.77		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(33,862		)	—			(143,562		)	59			—			(177,365		)
Add: Company’s share of net operating income from unconsolidated joint ventures	2,866			42,750			6,590			—			27,687			79,893
Company’s share of net operating income	$	510,009		$	42,750		$	444,086		$	267,223		$	287,774		$	1,551,842
% of Grand Totals	32.86		%	2.75		%	28.63		%	17.22		%	18.54		%	100.00		%

_______________


(1)	Rental Revenue is equal to total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

For the year ended December 31, 2017:



	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	776,279		$	—		$	969,371		$	345,519		$	414,103		$	2,505,272
Residential	4,745			—			—			—			11,851			16,596
Hotel	45,603			—			—			—			—			45,603
Total	826,627			—			969,371			345,519			425,954			2,567,471
% of Grand Totals	32.20		%	—		%	37.75		%	13.46		%	16.59		%	100.00		%
Rental Expenses:
Office	301,097			—			372,810			105,253			144,515			923,675
Residential	2,044			—			—			—			4,258			6,302
Hotel	32,059			—			—			—			—			32,059
Total	335,200			—			372,810			105,253			148,773			962,036
% of Grand Totals	34.84		%	—		%	38.76		%	10.94		%	15.46		%	100.00		%
Net operating income	$	491,427		$	—		$	596,561		$	240,266		$	277,181		$	1,605,435
% of Grand Totals	30.61		%	—		%	37.15		%	14.97		%	17.27		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(31,857		)	—			(142,916		)	528			—			(174,245		)
Add: Company’s share of net operating income from unconsolidated joint ventures	1,962			26,816			8,832			—			26,398			64,008
Company’s share of net operating income	$	461,532		$	26,816		$	462,477		$	240,794		$	303,579		$	1,495,198
% of Grand Totals	30.87		%	1.79		%	30.94		%	16.10		%	20.30		%	100.00		%

_______________

(1)

Earnings Per Share / Common Unit (Tables)

12 Months Ended

Dec. 31, 2019

Entity Information [Line Items]

Computation Of Basic And Diluted Earnings Per Share / Unit



	For the Year Ended December 31, 2019
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	511,034		154,582	$	3.31
Effect of Dilutive Securities:
Stock Based Compensation	—			301	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	511,034		154,883	$	3.30

	For the Year ended December 31, 2018
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	572,347		154,427	$	3.71
Allocation of undistributed earnings to participating securities	(101		)	—	—
Net income attributable to Boston Properties, Inc. common shareholders	$	572,246		154,427	$	3.71
Effect of Dilutive Securities:
Stock Based Compensation	—			255	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	572,246		154,682	$	3.70

	For the Year ended December 31, 2017
	Income (Numerator)			Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	451,939		154,190	$	2.93
Effect of Dilutive Securities:
Stock Based Compensation	—			200	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	451,939		154,390	$	2.93

Computation Of Basic And Diluted Earnings Per Share / Unit

Entity Information [Line Items]

Included in the number of units (the denominator) below are approximately 17,618,000, 17,485,000 and 17,471,000 redeemable common units for the years ended December 31, 2019, 2018 and 2017, respectively.



	For the Year Ended December 31, 2019
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	580,102	172,200	$	3.37
Effect of Dilutive Securities:
Stock Based Compensation	—		301	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	580,102	172,501	$	3.36



	For the Year ended December 31, 2018
	Income (Numerator)			Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	656,903		171,912	$	3.82
Allocation of undistributed earnings to participating securities	(113		)	—	—
Net income attributable to Boston Properties Limited Partnership common unitholders	$	656,790		171,912	$	3.82
Effect of Dilutive Securities:
Stock Based Compensation	—			255	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	656,790		172,167	$	3.81



	For the Year ended December 31, 2017
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	512,866	171,661	$	2.99
Effect of Dilutive Securities:
Stock Based Compensation	—		200	(0.01		)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	512,866	171,861	$	2.98

Stock Option and Incentive Plan (Tables)

12 Months Ended

Dec. 31, 2018

Stock Option and Incentive Plan and Stock Purchase Plan [Abstract]

Share-based Compensation, Stock Options, Activity [Table Text Block]

A summary of the status of Boston Properties, Inc.’s stock options as of December 31, 2019, 2018 and 2017 and changes during the years then ended are presented below:



	Shares		Weighted-Average Exercise Price
Outstanding at December 31, 2016	547,129		$	96.38
Exercised	(6,688	)	$	99.15
Outstanding at December 31, 2017	540,441		$	96.35
Exercised	—		$	—
Outstanding at December 31, 2018	540,441		$	96.35
Exercised	(145,088	)	$	96.27
Outstanding at December 31, 2019	395,353		$	96.37

Schedule of Stock Options Outstanding [Table Text Block]

The following table summarizes information about Boston Properties, Inc.’s stock options outstanding at December 31, 2019:



Options Outstanding				Options Exercisable
Number Outstanding at 12/31/19	Weighted-Average Remaining Contractual Life	Exercise Price		Number Exercisable at 12/31/19	Exercise Price
81,458	1.1 years	$	86.86	81,458	$	86.86
54,282	3.3 years	$	95.69	54,282	$	95.69
142,422	3.1 years	$	98.46	142,422	$	98.46
117,191	2.1 years	$	100.77	117,191	$	100.77

Selected Interim Financial Information (unaudited) (Tables)

3 Months Ended

Mar. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information [Table Text Block]

Boston Properties, Inc.

The tables below reflect Boston Properties, Inc.’s selected quarterly information for the years ended December 31, 2019 and 2018.



	2019 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per share amounts)
Total revenue	$	725,767	$	733,741	$	743,553	$	757,501
Net income	$	131,159	$	203,461	$	141,370	$	176,009
Net income attributable to Boston Properties, Inc. common shareholders	$	98,105	$	164,318	$	107,771	$	140,824
Income attributable to Boston Properties, Inc. per share—basic	$	0.63	$	1.06	$	0.70	$	0.91
Income attributable to Boston Properties, Inc. per share—diluted	$	0.63	$	1.06	$	0.70	$	0.91



	2018 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per share amounts)
Total revenue	$	661,151	$	664,484	$	686,284	$	705,157
Net income	$	216,312	$	160,565	$	150,445	$	185,241
Net income attributable to Boston Properties, Inc. common shareholders	$	176,021	$	128,681	$	119,118	$	148,529
Income attributable to Boston Properties, Inc. per share—basic	$	1.14	$	0.83	$	0.77	$	0.96
Income attributable to Boston Properties, Inc. per share—diluted	$	1.14	$	0.83	$	0.77	$	0.96

Boston Properties Limited Partnership

The tables below reflect Boston Properties Limited Partnership’s selected quarterly information for the years ended December 31, 2019 and 2018.



	2019 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per unit amounts)
Total revenue	$	725,767	$	733,741	$	743,553	$	757,501
Net income	$	134,837	$	205,822	$	143,212	$	177,851
Net income attributable to Boston Properties Limited Partnership common unitholders	$	113,382	$	185,715	$	122,117	$	158,888
Income attributable to Boston Properties Limited Partnership per unit—basic	$	0.66	$	1.08	$	0.71	$	0.92
Income attributable to Boston Properties Limited Partnership per unit—diluted	$	0.66	$	1.08	$	0.71	$	0.92



	2018 Quarter Ended
	March 31,		June 30,		September 30,		December 31,
	(in thousands, except for per unit amounts)
Total revenue	$	661,151	$	664,484	$	686,284	$	705,157
Net income	$	220,766	$	162,986	$	153,676	$	192,884
Net income attributable to Boston Properties Limited Partnership common unitholders	$	200,907	$	145,961	$	136,201	$	173,834
Income attributable to Boston Properties Limited Partnership per unit—basic	$	1.17	$	0.85	$	0.79	$	1.01
Income attributable to Boston Properties Limited Partnership per unit—diluted	$	1.17	$	0.85	$	0.79	$	1.01

Real Estate and Accumulated Depreciation Real Estate and Accumulated Depreciation (Tables)

12 Months Ended

Dec. 31, 2019

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

Real Estate and Accumulated Depreciation, By Property [Table Text Block]

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances		Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

					Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,274,028	$	1,796,252	$	1,532,654	$	202,612	$	1,796,252	$	1,735,266	$	—	$	—	$	3,531,518	$	313,158	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—		92,077		948,357		556,458		115,638		1,478,578		2,676		—		1,596,892		596,740		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—		179,697		847,410		415,228		195,987		1,246,348		—		—		1,442,335		633,711		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—		339,200		700,358		300,519		354,107		985,970		—		—		1,340,077		358,960		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	644,778		241,600		494,782		454,902		289,639		688,550		—		213,095		1,191,284		289,482		1977/1997	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—		200,349		946,205		—		200,349		946,205		—		—		1,146,554		38,727		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—		219,543		667,884		210,160		250,134		829,529		17,924		—		1,097,587		214,533		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—		285,263		603,167		51,928		285,263		655,095		—		—		940,358		116,857		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—		131,067		435,954		102,984		131,067		538,938		—		—		670,005		122,799		1971-1975/2017	2012	(1)
Times Square Tower	Office	New York, NY	—		165,413		380,438		113,222		169,193		489,880		—		—		659,073		217,303		2004	2000	(1)
Carnegie Center	Office	Princeton, NJ	—		142,666		316,856		152,280		94,240		462,882		54,680		—		611,802		208,331		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Atlantic Wharf	Office	Boston, MA	—		63,988		454,537		18,709		63,988		473,246		—		—		537,234		131,828		2011	2007	(1)
510 Madison Avenue	Office	New York, NY	—		103,000		253,665		25,495		103,000		279,160		—		—		382,160		72,213		2012	2010	(1)
Fountain Square	Office	Reston, VA	—		56,853		306,298		12,140		56,853		318,438		—		—		375,291		78,498		1986-1990	2012	(1)
599 Lexington Avenue	Office	New York, NY	—		81,040		100,507		188,572		87,852		282,267		—		—		370,119		183,291		1986	1997	(1)
680 Folsom Street	Office	San Francisco, CA	—		72,545		219,766		7,907		72,545		227,673		—		—		300,218		46,777		2014	2012	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—		—		183,541		113,627		109,038		188,130		—		—		297,168		59,190		2011	2008	(1)
145 Broadway	Office	Cambridge, MA	—		121		273,013		23,246		23,367		273,013		—		—		296,380		1,511		2019	1997	(1)
South of Market and Democracy Tower	Office	Reston, VA	—		13,603		237,479		26,415		13,687		263,810		—		—		277,497		99,478		2008-2009	2003	(1)
601 Massachusetts Avenue	Office	Washington, DC	—		95,310		165,173		3,945		95,322		169,106		—		—		264,428		24,502		2016	2008	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—		18,789		148,451		80,077		18,789		228,528		—		—		247,317		79,824		1985-1989	2011	(1)
Gateway Center	Office	San Francisco, CA	—		28,255		139,245		61,791		30,627		198,664		—		—		229,291		106,680		1984/1986/2002	1999	(1)
535 Mission Street	Office	San Francisco, CA	—		40,933		148,378		3,276		40,933		151,654		—		—		192,587		26,293		2015	2013	(1)
Reservoir Place	Office	Waltham, MA	—		18,605		104,124		53,718		20,108		156,339		—		—		176,447		70,870		1955/1987/2017	1997/1998	(1)
Mountain View Research Park	Office	Mountain View, CA	—		95,066		68,373		12,704		95,066		81,077		—		—		176,143		19,807		1977-1981/2007-2013	2013	(1)
1330 Connecticut Avenue	Office	Washington, DC	—		25,982		82,311		36,847		27,135		118,005		—		—		145,140		32,775		1984/2018	2004	(1)

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances	Original		Costs Capitalized Subsequent to Acquisition		Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

				Land	Building
Kingstowne Towne Center	Office	Alexandria, VA	—	18,021	109,038	3,376		18,062	112,373	—	—	130,435	44,294	2003-2006	2007	(1)
One Freedom Square	Office	Reston, VA	—	9,929	84,504	34,372		11,293	117,512	—	—	128,805	59,006	2000	2003	(1)
Capital Gallery	Office	Washington, DC	—	4,725	29,565	88,704		8,662	114,332	—	—	122,994	71,631	1981/2006	2007	(1)
Weston Corporate Center	Office	Weston, MA	—	25,753	92,312	(123	)	25,854	92,088	—	—	117,942	29,227	2010	2001	(1)
Two Freedom Square	Office	Reston, VA	—	13,930	77,739	23,209		15,420	99,458	—	—	114,878	50,668	2001	2003	(1)
One and Two Reston Overlook	Office	Reston, VA	—	16,456	66,192	24,181		16,179	90,650	—	—	106,829	51,503	1999	2000	(1)
Discovery Square	Office	Reston, VA	—	11,198	71,782	20,905		12,533	91,352	—	—	103,885	43,619	2001	2003	(1)
140 Kendrick Street	Office	Needham, MA	—	18,095	66,905	17,574		19,092	83,482	—	—	102,574	35,721	2000	2004	(1)
355 Main Street	Office	Cambridge, MA	—	18,863	53,346	27,582		21,173	78,618	—	—	99,791	26,439	1981/1996/2013	2006	(1)
880 & 890 Winter Street	Office	Waltham, MA	—	29,510	65,812	—		29,510	65,812	—	—	95,322	1,458	1998-1999	2019	(1)
10 CityPoint	Office	Waltham, MA	—	1,953	85,752	4,697		2,290	90,112	—	—	92,402	10,928	2016	1997	(1)
90 Broadway	Office	Cambridge, MA	—	19,104	52,078	19,857		20,785	70,254	—	—	91,039	23,621	1983/1998/2013	2006	(1)
230 CityPoint	Office	Waltham, MA	—	13,189	49,823	22,057		13,807	71,262	—	—	85,069	29,255	1992	2005	(1)
77 CityPoint	Office	Waltham, MA	—	13,847	60,383	10,556		14,023	70,763	—	—	84,786	27,172	2008	2001	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—	10,385	60,694	13,165		11,097	73,147	—	—	84,244	35,567	2003	1999	(1)
3625-3635 Peterson Way	Office	Santa Clara, CA	—	63,206	14,879	752		63,206	14,879	752	—	78,837	11,172	1979	2016	(1)
2440 West El Camino Real	Office	Mountain View, CA	—	16,741	51,285	5,454		16,741	56,739	—	—	73,480	13,090	1987/2003	2011	(1)
191 Spring Street	Office	Lexington, MA	—	2,850	59,751	7,695		3,151	67,145	—	—	70,296	21,917	1971/1995/2018	1997	(1)
300 Binney Street	Office	Cambridge, MA	—	18,080	51,262	140		18,080	51,402	—	—	69,482	11,146	2013	2009	(1)
Wisconsin Place	Office	Chevy Chase, MD	—	—	53,349	14,924		—	68,273	—	—	68,273	25,934	2009	2004	(1)
Reston Corporate Center	Office	Reston, VA	—	9,135	50,857	6,236		10,148	56,080	—	—	66,228	29,860	1984	1998	(1)
New Dominion Technology Park, Bldg. Two	Office	Herndon, VA	—	5,584	51,868	4,157		6,510	55,099	—	—	61,609	26,894	2004	1998	(1)
255 Main Street	Office	Cambridge, MA	—	134	25,110	34,124		548	58,820	—	—	59,368	33,543	1987	1997	(1)
University Place	Office	Cambridge, MA	3,602	—	37,091	16,001		7,418	45,674	—	—	53,092	29,423	1985	1998	(1)
New Dominion Technology Park, Bldg. One	Office	Herndon, VA	—	3,880	43,227	3,927		4,583	46,451	—	—	51,034	29,141	2001	1998	(1)
Sumner Square	Office	Washington, DC	—	624	28,745	21,344		3,535	47,178	—	—	50,713	27,093	1985	1999	(1)
200 West Street	Office	Waltham, MA	—	16,148	24,983	8,211		16,813	30,425	—	2,104	49,342	17,001	1999	1997	(1)
North First Business Park	Office	San Jose, CA	—	23,398	13,069	4,571		23,377	17,661	—	—	41,038	16,411	1981	2007	(1)
150 Broadway	Office	Cambridge, MA	—	850	25,042	8,540		1,323	33,109	—	—	34,432	19,875	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—	1,299	12,943	11,406		2,395	23,253	—	—	25,648	11,870	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—	998	1,426	18,547		1,264	19,707	—	—	20,971	14,312	1982	1997	(1)
201 Spring Street	Office	Lexington, MA	—	2,849	15,303	1,172		3,124	16,200	—	—	19,324	8,587	1997	1997	(1)
The Point	Office	Waltham, MA	—	6,395	10,040	421		6,492	10,364	—	—	16,856	1,349	2015	2007	(1)
33 Hayden Avenue	Office	Lexington, MA	—	266	3,234	12,898		425	15,973	—	—	16,398	5,678	1979	1997	(1)
690 Folsom Street	Office	San Francisco, CA	—	3,219	11,038	1,157		3,219	12,195	—	—	15,414	2,284	2015	2012	(1)

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances	Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

				Land	Building
92-100 Hayden Avenue	Office	Lexington, MA	—	594	6,748	7,529	802	14,069	—	—	14,871	12,041	1985	1997	(1)
181 Spring Street	Office	Lexington, MA	—	1,066	9,520	2,177	1,160	11,603	—	—	12,763	5,597	1999	1997	(1)
195 West Street	Office	Waltham, MA	—	1,611	6,652	4,218	1,858	10,623	—	—	12,481	8,352	1990	1997	(1)
7501 Boston Boulevard, Building Seven	Office	Springfield, VA	—	665	9,273	816	791	9,963	—	—	10,754	5,393	1997	1997	(1)
7435 Boston Boulevard, Building One	Office	Springfield, VA	—	392	3,822	4,983	659	8,538	—	—	9,197	6,344	1982	1997	(1)
7450 Boston Boulevard, Building Three	Office	Springfield, VA	—	1,165	4,681	2,591	1,430	7,007	—	—	8,437	3,575	1987	1998	(1)
32 Hartwell Avenue	Office	Lexington, MA	—	168	1,943	6,115	314	7,912	—	—	8,226	1,975	1968/1979/1987	1997	(1)
250 Binney Street	Office	Cambridge, MA	—	110	4,483	3,593	273	7,913	—	—	8,186	5,829	1983	1997	(1)
8000 Grainger Court, Building Five	Office	Springfield, VA	—	366	4,282	3,198	601	7,245	—	—	7,846	5,752	1984	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—	5,477	1,090	676	5,477	1,766	—	—	7,243	690	1977	2012	(1)
7300 Boston Boulevard, Building Thirteen	Office	Springfield, VA	—	608	4,773	1,007	661	5,727	—	—	6,388	1,984	2002	1997	(1)
17 Hartwell Avenue	Office	Lexington, MA	—	26	150	6,064	65	6,175	—	—	6,240	1,966	1968	1997	(1)
7601 Boston Boulevard, Building Eight	Office	Springfield, VA	—	200	878	5,060	551	5,587	—	—	6,138	4,689	1986	1997	(1)
7500 Boston Boulevard, Building Six	Office	Springfield, VA	—	138	3,749	1,640	367	5,160	—	—	5,527	4,237	1985	1997	(1)
8000 Corporate Court, Building Eleven	Office	Springfield, VA	—	136	3,071	1,596	774	4,029	—	—	4,803	3,191	1989	1997	(1)
7375 Boston Boulevard, Building Ten	Office	Springfield, VA	—	23	2,685	1,032	93	3,647	—	—	3,740	2,606	1988	1997	(1)
7374 Boston Boulevard, Building Four	Office	Springfield, VA	—	241	1,605	1,828	398	3,276	—	—	3,674	2,779	1984	1997	(1)
7451 Boston Boulevard, Building Two	Office	Springfield, VA	—	249	1,542	1,667	613	2,845	—	—	3,458	2,610	1982	1997	(1)
Signature at Reston	Residential	Reston, VA	—	27,076	190,580	393	27,076	190,973	—	—	218,049	8,773	2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—	9,243	127,248	2,939	9,245	130,185	—	—	139,430	4,566	2018	2015	(1)
The Avant at Reston Town Center	Residential	Reston, VA	—	20,350	91,995	830	20,350	92,825	—	—	113,175	14,728	2014	2010	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—	3,529	54,891	1,897	3,529	56,788	—	—	60,317	12,639	2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—	478	37,918	35,813	1,201	73,008	—	—	74,209	46,605	1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—	—	35,035	7,329	103	42,261	—	—	42,364	13,512	1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—	1,256	15,697	1,552	1,434	17,071	—	—	18,505	6,031	2006	2004	(1)
Kendall Center Blue Garage	Garage	Cambridge, MA	—	1,163	11,633	2,151	1,579	13,368	—	—	14,947	9,728	1990	1997	(1)
The Skylyne (MacArthur Station Residences)	Development	Oakland, CA	—	—	—	226,526	29,807	—	—	196,719	226,526	—	N/A	N/A	N/A
2100 Pennsylvania Avenue	Development	Washington, DC	—	—	—	224,380	185,129	—	—	39,251	224,380	1,024	N/A	N/A	N/A
Reston Gateway	Development	Reston, VA	—	—	—	150,632	—	—	—	150,632	150,632	—	N/A	1998	N/A
17Fifty Presidents Street	Development	Reston, VA	—	—	—	99,816	—	—	—	99,816	99,816	—	N/A	2013	N/A

Boston Properties, Inc. Schedule 3 - Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

Property Name	Type	Location	Encumbrances				Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements				Building and Improvements				Land Held for Development				Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

							Land		Building
20 CityPoint	Development	Waltham, MA	—				4,721		52,039		20,007		4,721				52,039				—				20,007		76,767		1,136		N/A	2007	N/A
325 Main Street	Development	Cambridge, MA	—				174		—		68,903		965				—				—				68,112		69,077		—		N/A	1997	N/A
North First Master Plan	Land	San Jose, CA	—				35,004		—		3,932		—				—				38,936				—		38,936		—		N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—				—		—		34,889		—				—				34,889				—		34,889		—		N/A	2006	N/A
425 Fourth Street	Land	San Francisco, CA	—				—		—		22,074		—				—				22,074				—		22,074		—		N/A	N/A	N/A
Springfield Metro Center	Land	Springfield, VA	—				—		—		19,844		—				—				19,844				—		19,844		—		N/A	2007	N/A
Reston Gateway Master Plan	Land	Reston, VA	—				—		—		18,292		—				—				18,292				—		18,292		—		N/A	1998	N/A
214 Third Avenue	Land	Waltham, MA	—				—		—		17,692		—				—				17,692				—		17,692		—		N/A	2006	N/A
103 Fourth Avenue	Land	Waltham, MA	—				—		—		12,826		—				—				12,826				—		12,826		—		N/A	2007	N/A
Crane Meadow	Land	Marlborough, MA	—				—		—		8,866		—				—				8,866				—		8,866		—		N/A	2000	N/A
Broad Run Business Park	Land	Loudoun County, VA	—				—		—		2,396		—				—				2,396				—		2,396		—		N/A	1998	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—				—		—		1,693		—				—				1,693				—		1,693		—		N/A	1997	N/A
Weston Quarry	Land	Weston, MA	—				—		—		1,249		—				—				1,249				—		1,249		—		N/A	2001	N/A
Reston Overlook Master Plan	Land	Reston, VA	—				—		—		39		—				—				39				—		39		—		N/A	2000	N/A

			$	2,922,408	(2	)	$	5,024,060	$	13,057,336	$	4,763,301	$	5,474,337	(3	)	$	16,325,796	(4	)	$	254,828	(5	)	$	789,736	$	22,844,697	$	5,239,179

The aggregate cost and accumulated depreciation for tax purposes was approximately $18.6 billion and $4.0 billion, respectively.


(1)	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.


(2)	Includes unamortized deferred financing costs totaling approximately $(26.7) million.


(3)	Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $214,091 and $148,640, respectively.


(4)	Includes Right of Use Assets - Finance Leases of approximately $23,303.

(5)

Includes pre-development costs.

Activity of Real Estate and Accumulated Depreciation [Table Text Block]

A summary of activity for real estate and accumulated depreciation is as follows:



	2019			2018			2017
Real Estate:
Balance at the beginning of the year	$	21,605,545		$	21,058,714		$	20,114,576
Additions to/improvements of real estate	1,671,898			1,043,379			1,099,286
Assets sold/written-off	(432,746		)	(496,548		)	(155,148		)
Balance at the end of the year	$	22,844,697		$	21,605,545		$	21,058,714
Accumulated Depreciation:
Balance at the beginning of the year	$	4,871,102		$	4,566,570		$	4,201,891
Depreciation expense	564,938			533,342			497,059
Assets sold/written-off	(196,861		)	(228,810		)	(132,380		)
Balance at the end of the year	$	5,239,179		$	4,871,102		$	4,566,570

Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

Real Estate and Accumulated Depreciation, By Property [Table Text Block]

Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

					Original				Costs Capitalized Subsequent to Acquisition			Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances		Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,274,028	$	1,796,252	$	1,532,654	$	202,612		$	1,796,252	$	1,735,266	$	—	$	—	$	3,531,518	$	313,158	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—		92,077		948,357		496,088			100,540		1,433,306		2,676		—		1,536,522		580,797		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—		179,697		847,410		352,847			180,420		1,199,534		—		—		1,379,954		617,163		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—		339,200		700,358		240,911			339,200		941,269		—		—		1,280,469		343,191		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	644,778		241,600		494,782		417,816			279,281		661,822		—		213,095		1,154,198		280,028		1977/1997	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—		200,349		946,205		—			200,349		946,205		—		—		1,146,554		38,727		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—		219,543		667,884		210,160			250,134		829,529		17,924		—		1,097,587		214,533		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—		285,263		603,167		51,928			285,263		655,095		—		—		940,358		116,857		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—		131,067		435,954		102,984			131,067		538,938		—		—		670,005		122,799		1971-1975/2017	2012	(1)
Times Square Tower	Office	New York, NY	—		165,413		380,438		75,243			159,694		461,400		—		—		621,094		207,272		2004	2000	(1)
Carnegie Center	Office	Princeton, NJ	—		142,666		316,856		137,317			90,498		451,661		54,680		—		596,839		204,380		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Atlantic Wharf	Office	Boston, MA	—		63,988		454,537		18,709			63,988		473,246		—		—		537,234		131,828		2011	2007	(1)
510 Madison Avenue	Office	New York, NY	—		103,000		253,665		25,495			103,000		279,160		—		—		382,160		72,213		2012	2010	(1)
Fountain Square	Office	Reston, VA	—		56,853		306,298		12,140			56,853		318,438		—		—		375,291		78,498		1986-1990	2012	(1)
599 Lexington Avenue	Office	New York, NY	—		81,040		100,507		161,330			81,040		261,837		—		—		342,877		176,101		1986	1997	(1)
680 Folsom Street	Office	San Francisco, CA	—		72,545		219,766		7,907			72,545		227,673		—		—		300,218		46,777		2014	2012	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—		—		183,541		113,627			109,038		188,130		—		—		297,168		59,190		2011	2008	(1)
145 Broadway	Office	Cambridge, MA	—		121		273,013		23,043			23,164		273,013		—		—		296,177		1,511		2019	1997	(1)
South of Market and Democracy Tower	Office	Reston, VA	—		13,603		237,479		26,079			13,603		263,558		—		—		277,161		99,406		2008-2009	2003	(1)
601 Massachusetts Avenue	Office	Washington, DC	—		95,310		165,173		3,933			95,310		169,106		—		—		264,416		24,502		2016	2008	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—		18,789		148,451		80,077			18,789		228,528		—		—		247,317		79,824		1985-1989	2011	(1)
Gateway Center	Office	San Francisco, CA	—		28,255		139,245		55,402			29,029		193,873		—		—		222,902		104,993		1984/1986/2002	1999	(1)
535 Mission Street	Office	San Francisco, CA	—		40,933		148,378		3,276			40,933		151,654		—		—		192,587		26,293		2015	2013	(1)
Mountain View Research Park	Office	Mountain View, CA	—		95,066		68,373		12,704			95,066		81,077		—		—		176,143		19,807		1977-1981/2007-2013	2013	(1)
Reservoir Place	Office	Waltham, MA	—		18,605		104,124		49,643			19,089		153,283		—		—		172,372		69,794		1955/1987/2017	1997/1998	(1)
1330 Connecticut Avenue	Office	Washington, DC	—		25,982		82,311		32,234			25,982		114,545		—		—		140,527		31,553		1984/2018	2004	(1)
Kingstowne Towne Center	Office	Alexandria, VA	—		18,021		109,038		3,212			18,021		112,250		—		—		130,271		44,258		2003-2006	2007	(1)
One Freedom Square	Office	Reston, VA	—		9,929		84,504		28,735			9,883		113,285		—		—		123,168		57,516		2000	2003	(1)
Weston Corporate Center	Office	Weston, MA	—		25,753		92,312		(123		)	25,854		92,088		—		—		117,942		29,227		2010	2001	(1)
Capital Gallery	Office	Washington, DC	—		4,725		29,565		78,573			6,128		106,735		—		—		112,863		68,953		1981/2006	2007	(1)
Two Freedom Square	Office	Reston, VA	—		13,930		77,739		16,997			13,866		94,800		—		—		108,666		49,028		2001	2003	(1)

Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

				Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances	Land	Building
One and Two Reston Overlook	Office	Reston, VA	—	16,456	66,192	19,763	15,074	87,337	—	—	102,411	50,336	1999	2000	(1)
355 Main Street	Office	Cambridge, MA	—	18,863	53,346	27,284	21,098	78,395	—	—	99,493	26,362	1981/1996/2013	2006	(1)
140 Kendrick Street	Office	Needham, MA	—	18,095	66,905	13,584	18,095	80,489	—	—	98,584	34,667	2000	2004	(1)
Discovery Square	Office	Reston, VA	—	11,198	71,782	15,360	11,146	87,194	—	—	98,340	42,152	2001	2003	(1)
880 & 890 Winter Street	Office	Waltham, MA	—	29,510	65,812	—	29,510	65,812	—	—	95,322	1,458	1998-1999	2019	(1)
10 CityPoint	Office	Waltham, MA	—	1,953	85,752	4,534	2,127	90,112	—	—	92,239	10,928	2016	1997	(1)
90 Broadway	Office	Cambridge, MA	—	19,104	52,078	19,678	20,741	70,119	—	—	90,860	23,581	1983/1998/2013	2006	(1)
77 CityPoint	Office	Waltham, MA	—	13,847	60,383	10,451	13,997	70,684	—	—	84,681	27,148	2008	2001	(1)
230 CityPoint	Office	Waltham, MA	—	13,189	49,823	20,440	13,403	70,049	—	—	83,452	28,831	1992	2005	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—	10,385	60,694	10,178	10,350	70,907	—	—	81,257	34,777	2003	1999	(1)
3625-3635 Peterson Way	Office	Santa Clara, CA	—	63,206	14,879	752	63,206	14,879	752	—	78,837	11,172	1979	2016	(1)
2440 West El Camino Real	Office	Mountain View, CA	—	16,741	51,285	5,454	16,741	56,739	—	—	73,480	13,090	1987/2003	2011	(1)
191 Spring Street	Office	Lexington, MA	—	2,850	59,751	7,063	2,850	66,814	—	—	69,664	21,801	1971/1995/2018	1997	(1)
300 Binney Street	Office	Cambridge, MA	—	18,080	51,262	140	18,080	51,402	—	—	69,482	11,146	2013	2009	(1)
Wisconsin Place	Office	Chevy Chase, MD	—	—	53,349	14,924	—	68,273	—	—	68,273	25,934	2009	2004	(1)
Reston Corporate Center	Office	Reston, VA	—	9,135	50,857	3,625	9,496	54,121	—	—	63,617	29,170	1984	1998	(1)
New Dominion Technology Park, Bldg. Two	Office	Herndon, VA	—	5,584	51,868	412	5,574	52,290	—	—	57,864	25,900	2004	1998	(1)
255 Main Street	Office	Cambridge, MA	—	134	25,110	32,468	134	57,578	—	—	57,712	33,108	1987	1997	(1)
University Place	Office	Cambridge, MA	3,602	—	37,091	14,551	7,055	44,587	—	—	51,642	29,044	1985	1998	(1)
Sumner Square	Office	Washington, DC	—	624	28,745	19,264	3,015	45,618	—	—	48,633	26,547	1985	1999	(1)
New Dominion Technology Park, Bldg. One	Office	Herndon, VA	—	3,880	43,227	1,117	3,880	44,344	—	—	48,224	28,398	2001	1998	(1)
200 West Street	Office	Waltham, MA	—	16,148	24,983	5,550	16,148	28,429	—	2,104	46,681	16,298	1999	1997	(1)
North First Business Park	Office	San Jose, CA	—	23,398	13,069	4,548	23,371	17,644	—	—	41,015	16,411	1981	2007	(1)
150 Broadway	Office	Cambridge, MA	—	850	25,042	6,535	822	31,605	—	—	32,427	19,342	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—	1,299	12,943	9,300	1,868	21,674	—	—	23,542	11,312	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—	998	1,426	17,783	1,073	19,134	—	—	20,207	14,114	1982	1997	(1)
201 Spring Street	Office	Lexington, MA	—	2,849	15,303	73	2,849	15,376	—	—	18,225	8,295	1997	1997	(1)
The Point	Office	Waltham, MA	—	6,395	10,040	421	6,492	10,364	—	—	16,856	1,349	2015	2007	(1)
33 Hayden Avenue	Office	Lexington, MA	—	266	3,234	12,261	266	15,495	—	—	15,761	5,510	1979	1997	(1)
690 Folsom Street	Office	San Francisco, CA	—	3,219	11,038	1,157	3,219	12,195	—	—	15,414	2,284	2015	2012	(1)
92-100 Hayden Avenue	Office	Lexington, MA	—	594	6,748	6,800	619	13,523	—	—	14,142	11,847	1985	1997	(1)
181 Spring Street	Office	Lexington, MA	—	1,066	9,520	1,800	1,066	11,320	—	—	12,386	5,498	1999	1997	(1)
195 West Street	Office	Waltham, MA	—	1,611	6,652	3,229	1,611	9,881	—	—	11,492	8,087	1990	1997	(1)
7501 Boston Boulevard, Building Seven	Office	Springfield, VA	—	665	9,273	311	665	9,584	—	—	10,249	5,257	1997	1997	(1)

Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

				Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances	Land	Building
7435 Boston Boulevard, Building One	Office	Springfield, VA	—	392	3,822	4,290	486	8,018	—	—	8,504	6,162	1982	1997	(1)
7450 Boston Boulevard, Building Three	Office	Springfield, VA	—	1,165	4,681	2,177	1,327	6,696	—	—	8,023	3,462	1987	1998	(1)
32 Hartwell Avenue	Office	Lexington, MA	—	168	1,943	5,529	168	7,472	—	—	7,640	1,819	1968/1979/1987	1997	(1)
250 Binney Street	Office	Cambridge, MA	—	110	4,483	2,939	110	7,422	—	—	7,532	5,660	1983	1997	(1)
8000 Grainger Court, Building Five	Office	Springfield, VA	—	366	4,282	2,604	453	6,799	—	—	7,252	5,597	1984	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—	5,477	1,090	676	5,477	1,766	—	—	7,243	690	1977	2012	(1)
7300 Boston Boulevard, Building Thirteen	Office	Springfield, VA	—	608	4,773	795	608	5,568	—	—	6,176	1,928	2002	1997	(1)
17 Hartwell Avenue	Office	Lexington, MA	—	26	150	5,907	26	6,057	—	—	6,083	1,924	1968	1997	(1)
7601 Boston Boulevard, Building Eight	Office	Springfield, VA	—	200	878	4,367	378	5,067	—	—	5,445	4,507	1986	1997	(1)
7500 Boston Boulevard, Building Six	Office	Springfield, VA	—	138	3,749	1,107	234	4,760	—	—	4,994	4,097	1985	1997	(1)
8000 Corporate Court, Building Eleven	Office	Springfield, VA	—	136	3,071	1,245	686	3,766	—	—	4,452	3,094	1989	1997	(1)
7375 Boston Boulevard, Building Ten	Office	Springfield, VA	—	23	2,685	851	47	3,512	—	—	3,559	2,562	1988	1997	(1)
7374 Boston Boulevard, Building Four	Office	Springfield, VA	—	241	1,605	1,445	303	2,988	—	—	3,291	2,681	1984	1997	(1)
7451 Boston Boulevard, Building Two	Office	Springfield, VA	—	249	1,542	1,354	535	2,610	—	—	3,145	2,526	1982	1997	(1)
Signature at Reston	Residential	Reston, VA	—	27,076	190,580	393	27,076	190,973	—	—	218,049	8,773	2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—	9,243	127,248	2,939	9,245	130,185	—	—	139,430	4,566	2018	2015	(1)
The Avant at Reston Town Center	Residential	Reston, VA	—	20,350	91,995	830	20,350	92,825	—	—	113,175	14,728	2014	2010	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—	3,529	54,891	1,897	3,529	56,788	—	—	60,317	12,639	2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—	478	37,918	32,922	478	70,840	—	—	71,318	45,842	1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—	—	35,035	6,915	—	41,950	—	—	41,950	13,404	1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—	1,256	15,697	840	1,256	16,537	—	—	17,793	5,847	2006	2004	(1)
Kendall Center Blue Garage	Garage	Cambridge, MA	—	1,163	11,633	486	1,163	12,119	—	—	13,282	9,290	1990	1997	(1)
The Skylyne (MacArthur Station Residences)	Development	Oakland, CA	—	—	—	226,526	29,807	—	—	196,719	226,526	—	N/A	N/A	N/A
2100 Pennsylvania Avenue	Development	Washington, DC	—	—	—	224,380	185,129	—	—	39,251	224,380	1,024	N/A	N/A	N/A
Reston Gateway	Development	Reston, VA	—	—	—	150,632	—	—	—	150,632	150,632	—	N/A	1998	N/A
17Fifty Presidents Street	Development	Reston, VA	—	—	—	99,816	—	—	—	99,816	99,816	—	N/A	2013	N/A
20 CityPoint	Development	Waltham, MA	—	4,721	52,039	20,007	4,721	52,039	—	20,007	76,767	1,136	N/A	2007	N/A
325 Main Street	Development	Cambridge, MA	—	174	—	68,710	772	—	—	68,112	68,884	—	N/A	1997	N/A
North First Master Plan	Land	San Jose, CA	—	35,004	—	3,932	—	—	38,936	—	38,936	—	N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—	—	—	34,889	—	—	34,889	—	34,889	—	N/A	2006	N/A

Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2019 (dollars in thousands)

							Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements				Building and Improvements				Land Held for Development				Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances				Land		Building
425 Fourth Street	Land	San Francisco, CA	—				—		—		22,074		—				—				22,074				—		22,074		—		N/A	N/A	N/A
Springfield Metro Center	Land	Springfield, VA	—				—		—		19,844		—				—				19,844				—		19,844		—		N/A	2007	N/A
Reston Gateway Master Plan	Land	Reston, VA	—				—		—		18,292		—				—				18,292				—		18,292		—		N/A	1998	N/A
214 Third Avenue	Land	Waltham, MA	—				—		—		17,692		—				—				17,692				—		17,692		—		N/A	2006	N/A
103 Fourth Avenue	Land	Waltham, MA	—				—		—		12,826		—				—				12,826				—		12,826		—		N/A	2007	N/A
Crane Meadow	Land	Marlborough, MA	—				—		—		8,866		—				—				8,866				—		8,866		—		N/A	2000	N/A
Broad Run Business Park	Land	Loudoun County, VA	—				—		—		2,396		—				—				2,396				—		2,396		—		N/A	1998	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—				—		—		1,693		—				—				1,693				—		1,693		—		N/A	1997	N/A
Weston Quarry	Land	Weston, MA	—				—		—		1,249		—				—				1,249				—		1,249		—		N/A	2001	N/A
Reston Overlook Master Plan	Land	Reston, VA	—				—		—		39		—				—				39				—		39		—		N/A	2000	N/A

			$	2,922,408	(2	)	$	5,024,060	$	13,057,336	$	4,368,080	$	5,373,884	(3	)	$	16,031,028	(4	)	$	254,828	(5	)	$	789,736	$	22,449,476	$	5,135,289

The aggregate cost and accumulated depreciation for tax purposes was approximately $20.7 billion and $4.5 billion, respectively.


(1)	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.


(2)	Includes unamortized deferred financing costs totaling approximately $(26.7) million.


(3)	Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $214,091 and $148,640, respectively.


(4)	Includes Right of Use Assets - Finance Leases of approximately $23,303.

(5)

Includes pre-development costs.

Activity of Real Estate and Accumulated Depreciation [Table Text Block]

A summary of activity for real estate and accumulated depreciation is as follows:



	2019			2018			2017
Real Estate:
Balance at the beginning of the year	$	21,207,189		$	20,647,236		$	19,701,185
Additions to/improvements of real estate	1,671,898			1,043,379			1,099,286
Assets sold/written-off	(429,611		)	(483,426		)	(153,235		)
Balance at the end of the year	$	22,449,476		$	21,207,189		$	20,647,236
Accumulated Depreciation:
Balance at the beginning of the year	$	4,773,800		$	4,473,895		$	4,116,020
Depreciation expense	557,130			525,584			488,919
Assets sold/written-off	(195,641		)	(225,679		)	(131,044		)
Balance at the end of the year	$	5,135,289		$	4,773,800		$	4,473,895

Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

Organization (Details) ft² in Millions	12 Months Ended
Organization (Details) ft² in Millions	Dec. 31, 2019 ft² Real_Estate_Properties yr shares	Dec. 31, 2018 shares
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)	89.60%	89.70%
Restriction on redemption of OP units from date of issuance (years) \| yr	1
One OP unit is equivalent to one share of Common Stock (in shares) \| shares	1
OP unit conversion rate (in shares) \| shares	1
Number Of series Of preferred units outstanding	1
Number of VIEs - Consolidated	6
Number of VIEs - Total	8
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	196
Net Rentable Area (in sf) \| ft²	52.0
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	11
Net Rentable Area (in sf) \| ft²	5.5
Total Office Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	177
Number of VIEs - Consolidated	5
Office Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties	9
Retail Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	12
Residential Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	6
Residential Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties	2
Hotel Property [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	1
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Real Estate Properties [Line Items]
Preferred Stock, Dividend Rate, Percentage	5.25%
Preferred stock / units, shares / units outstanding (in shares / units) \| shares	80,000	80,000
Depositary shares of Series B Cumulative Redeemable Preferred [Member]
Real Estate Properties [Line Items]
Preferred stock / units, shares / units outstanding (in shares / units) \| shares	8,000,000
Series B Preferred Units [Member]
Real Estate Properties [Line Items]
Preferred stock / units, shares / units outstanding (in shares / units) \| shares	80,000

Summary Of Significant Accounting Policies (Narrative) (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) yr	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jan. 01, 2019 USD ($)
Entity Information [Line Items]
Probable Sale Term of Property After Classified As Held For Sale (Years) \| yr		1
Interest costs capitalized		$ 54,911,000	$ 65,766,000	$ 61,070,000
Salaries And Related Costs Capitalized		10,400,000	12,500,000	13,200,000
Cash FDIC Insured Limit	$ 250,000	250,000
Separate Unrestricted Cash For Deferred Compensation Plans	36,700,000	36,700,000	28,200,000
Gains (losses) from investments in securities		6,417,000	(1,865,000)	3,678,000
Internal Leasing Salaries And Related Costs Capitalized			5,400,000	5,000,000.0
Straight-line rent adjustments		58,400,000	51,900,000	54,800,000
Above and below market rent adjustments, net		$ 20,900,000	23,800,000	23,500,000
REIT Annual Taxable Income Distribution Requirement Percentage, Minimum		90.00%
Company Annual Taxable Income Distribution Percentage		100.00%
Cumulative effect of a change in accounting principle		$ 4,379,000	(5,496,000)	2,035,000
Right of use assets - operating leases	148,640,000	148,640,000			$ 151,800,000
Operating Lease, Liability	200,180,000	200,180,000			$ 199,300,000
Redeemable Noncontrolling Interest, Equity, Carrying Amount	8,365,000	8,365,000
Accounts Payable and Accrued Liabilities	$ 377,553,000	377,553,000	276,645,000
Lessee, Finance Lease, Description	four
Boston Properties Limited Partnership
Entity Information [Line Items]
Interest costs capitalized		54,911,000	65,766,000	61,070,000
Gains (losses) from investments in securities		6,417,000	(1,865,000)	3,678,000
Right of use assets - operating leases	$ 148,640,000	148,640,000
Operating Lease, Liability	200,180,000	200,180,000
Redeemable Noncontrolling Interest, Equity, Carrying Amount	8,365,000	8,365,000
Accounts Payable and Accrued Liabilities	377,553,000	377,553,000	276,645,000
deferred compenstation for directors [Member]
Entity Information [Line Items]
Change in classification of director deferred compensation plan		8,400,000
Redeemable Noncontrolling Interest, Equity, Carrying Amount	8,100,000	8,100,000
Accounts Payable and Accrued Liabilities	$ 300,000	300,000
Dividends In Excess Of Earnings [Member]
Entity Information [Line Items]
Cumulative effect of a change in accounting principle		3,864,000	(4,933,000)	272,000
Noncontrolling Interests [Member]
Entity Information [Line Items]
Cumulative effect of a change in accounting principle		445,000	$ (563,000)	$ 1,763,000
Noncontrolling interest - property partnerships [Member]
Entity Information [Line Items]
Cumulative effect of a change in accounting principle		$ 70,000

Summary Of Significant Accounting Policies Schedule of Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2019
Land Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	25 years
Land Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	40 years
Building and Building Improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	10 years
Building and Building Improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	40 years
Tenant Improvement [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life, description	Shorter of useful life or terms of related lease
Furniture, fixtures and equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	3 years
Furniture, fixtures and equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life (years)	7 years

Summary Of Significant Accounting Policies Schedule of Finite Lived Intangible Assets Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Finite-Lived Intangible Assets [Line Items]
2020	$ 17,536
2021	11,001
2022	5,918
2023	4,286
2024	2,510
Acquired Above-Market Lease Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
2020	5,440
2021	3,054
2022	357
2023	183
2024	135
Acquired Below-Market Lease Intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
2020	10,673
2021	6,455
2022	5,699
2023	5,558
2024	$ 4,043

Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable	$ 80,000	$ 80,000
Note receivable	15,920	19,468
Mortgage notes payable, net	2,922,408	2,964,572
Unsecured senior notes, net	8,390,459	7,544,697
Unsecured line of credit	0	0
Unsecured term loan, net	498,939	498,488
Total	2,949,154
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable	80,000	80,000
Note receivable	15,920	19,468
Total	95,920	99,468
Mortgage notes payable, net	2,922,408	2,964,572
Unsecured senior notes, net	8,390,459	7,544,697
Unsecured line of credit	0	0
Unsecured term loan, net	498,939	498,488
Total	11,811,806	11,007,757
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable	81,931	80,000
Note receivable	14,978	19,468
Total	96,909	99,468
Mortgage notes payable, net	2,984,956	2,903,925
Unsecured senior notes, net	8,826,375	7,469,338
Unsecured line of credit	0	0
Unsecured term loan, net	500,561	500,783
Total	$ 12,311,892	$ 10,874,046

Summary Of Significant Accounting Policies Lessee, Lease Costs and Other Information (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2019

USD ($)

Leases [Abstract]

Finance leases under development

Operating lease costs

$ 14,573

Amortization of right of use asset

^[1]

Interest on lease liabilities

$ 47

^[2]

Operating Lease, Weighted Average Remaining Lease Term

51 years

Finance Lease, Weighted Average Remaining Lease Term

71 years

Operating Lease, Weighted Average Discount Rate, Percent

5.70%

Finance Lease, Weighted Average Discount Rate, Percent

6.20%

[1]

[2]

Three of the finance leases relate to assets under development and as such, the entire interest amount was capitalized.

Summary Of Significant Accounting Policies Future Minimum Lease Payments for Ground Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Leases [Abstract]
2019	$ 11,425
2020	18,425
2021	25,310
2022	8,894
2023	9,084
Thereafter	$ 567,232

Summary Of Significant Accounting Policies Future Minimum Lease Payments, Capital Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	$ 1,441
2020	12,682
2021	2,123
2022	1,253
2023	944
Thereafter	73,241
Total expected minimum lease payments	91,684
Interest portion	(27,497)
Present value of expected net minimum lease payments	$ 64,187

Summary Of Significant Accounting Policies Lease Liability Maturity Schedule (Details) - USD ($)
$ in Thousands

Dec. 31, 2019

Jan. 01, 2019

Leases [Abstract]

Lessee, Finance Lease, Option to Extend, Reasonably Certain 2024

$ 38,700

Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]

10,050

24,973

18,041

10,322

9,277

557,954

630,617

Less: interest portion

(430,437)

Finance Lease Liabilities, Payments, Due [Abstract]

200,180

$ 199,300

834

5,960

10,208

9,708

^[1]

48,518

Thereafter

1,383,242

1,458,470

(1,234,428)

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]

$ 224,042

[1]	Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company is reasonably certain it will exercise.

Summary Of Significant Accounting Policies Lessor, Lease Income Table (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Fixed contractual payments	$ 2,261,260
Variable lease payments	496,754
Lease	$ 2,758,014

Summary Of Significant Accounting Policies Schedule of Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes (Details) - $ / shares

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Dec. 17, 2019

Dividends treatment for federal tax purposes.

$ 3.15

^[1]

$ 3.57

^[2]

$ 2.91

^[3]

Dividends Treatment For Federal Tax Purposes, Percentage

100.00%

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]

$ 0.98

Dividend Declared

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]

$ 0.98

$ 0.95

$ 0.80

Allocated to fiscal 2020

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]

0.94

Allocated to fiscal 2019

Special dividend / distribution (per share / common unit amount)

0.04

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]

0.26

Allocated to fiscal 2018

Special dividend / distribution (per share / common unit amount)

0.69

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]

0.33

Allocated to fiscal 2017

Special dividend / distribution (per share / common unit amount)

0.47

Capital Gains Income

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]

Dividends treatment for federal tax purposes.

$ 0.16

$ 0.78

$ 0.05

Dividends Treatment For Federal Tax Purposes, Percentage

5.16%

21.83%

1.71%

Ordinary Income

Tax Treatment Of Common Dividends Per Share For Federal Tax Purposes [Line Items]

Dividends treatment for federal tax purposes.

$ 2.99

$ 2.79

$ 2.86

Dividends Treatment For Federal Tax Purposes, Percentage

94.84%

78.17%

98.29%

[1]	The fourth quarter 2019 regular quarterly dividend was $0.98 per common share of which approximately $0.04 per common share was allocable to 2019 and approximately $0.94 per common share is allocable to 2020.
[2]	The fourth quarter 2018 regular quarterly dividend was $0.95 per common share of which approximately $0.69 per common share was allocable to 2018 and approximately $0.26 per common share is allocable to 2019.
[3]	The fourth quarter 2017 regular quarterly dividend was $0.80 per common share of which approximately $0.47 per common share was allocable to 2017 and approximately $0.33 per common share is allocable to 2018.

Real Estate Schedule of Real Estate Properties (Details) - USD ($)
$ in Thousands

Dec. 31, 2019

Jan. 01, 2019

Dec. 31, 2018

Land

$ 5,111,606

$ 5,072,568

237,394

Land held for future development

148,640

$ 151,800

^[1]

254,828

200,498

Buildings and improvements

13,646,054

13,356,751

Tenant improvements

2,656,439

2,396,932

Furniture, Fixtures and Equipment

44,313

44,351

Construction in progress

789,736

578,796

Less: accumulated depreciation

22,889,010

21,649,896

(5,266,798)

(4,897,777)

Total real estate

17,622,212

16,752,119

Land

5,011,153

4,971,475

237,394

Land held for future development

148,640

^[1]

254,828

200,498

Buildings and improvements

13,351,286

13,059,488

Tenant improvements

2,656,439

2,396,932

Furniture, Fixtures and Equipment

44,313

44,351

Construction in progress

789,736

578,796

Less: accumulated depreciation

22,493,789

21,251,540

(5,162,908)

(4,800,475)

Total real estate

$ 17,330,881

$ 16,451,065

[1]	Includes pre-development costs.

Real Estate (Narrative) (Details)
$ in Thousands

1 Months Ended

3 Months Ended

4 Months Ended

5 Months Ended

6 Months Ended

12 Months Ended

Dec. 20, 2019

USD ($)

Sep. 20, 2019

USD ($)

ft²

Jul. 16, 2019

USD ($)

ft²

Jun. 28, 2019

USD ($)

ft²

Jun. 03, 2019

USD ($)

ft²

May 09, 2019

USD ($)

ft²

Jan. 24, 2019

USD ($)

ft²

Jan. 23, 2019

USD ($)

Dec. 31, 2019

USD ($)

ft²

Sep. 30, 2019

USD ($)

ft²

Jun. 30, 2019

USD ($)

Mar. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Sep. 30, 2018

USD ($)

Jun. 30, 2018

USD ($)

Mar. 31, 2018

USD ($)

Dec. 31, 2019

USD ($)

ft²

Jun. 02, 2019

USD ($)

Jun. 27, 2019

USD ($)

Dec. 31, 2019

USD ($)

ft²

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Oct. 24, 2019

ft²

Aug. 27, 2019

USD ($)

ft²

Real_Estate_Properties

Jun. 01, 2019

ft²

Apr. 18, 2019

USD ($)

Jan. 10, 2019

USD ($)

ft²

$ 677,764

$ 645,649

$ 617,547

$ 237,394

237,394

224,042

$ 224,042

224,042

90,824

455,409

29,810

709

182,356

7,663

2600 Tower Oaks Boulevard [Member]

87,392

345,717

109,015

Revenues

$ 757,501

$ 743,553

$ 733,741

$ 725,767

$ 705,157

$ 686,284

$ 664,484

$ 661,151

$ 2,960,562

2,717,076

2,602,076

179,000

$ 22,700

21,400

$ (600)

3,100

One Tower Center [Member]

$ (200)

(600)

(100)

410,000

$ 38,000

$ 36,600

$ (800)

24,000

164 Lexington Road [Member]

$ (900)

(2,700)

(3,500)

64,000

$ 4,000

3,800

2,500

Washingtonian North [Member]

$ (100)

(200)

$ 7,800

7,300

$ (100)

1,800

325 Main Street

Term of Lease Signed (in years)

15-year

115,000

$ 9,900

20 CityPoint

211,000

200 West Street

261,000

145 Broadway

483,000

1,100,000

65 years

5.6

$ 134,800

122,600

$ 122,563

2100 Pennsylvania Avenue

Term of Lease Signed (in years)

16-year

Square Footage Of Signed Lease | ft²

300,000

470,000

75 years

$ 185,100

Prepaid Rent

15,000

Finance lease - right of use asset -prepaid rent

164,977

15,000

Finance lease - right of use asset - initial direct costs

$ 5,100

Lessee, finance lease, term of amortization

75 years

Carnegie Center

880 & 890 Winter Street [Member]

1,700,000

Aggregate purchase price

$ 51,500

Deferred purchase price

$ 8,600

Number of real estate properties | Real_Estate_Properties

392,000

Aggregate purchase price

$ 106,000

$ (600)

Revenues

4,900

$ 669,956

637,891

$ 237,394

237,394

224,042

$ 224,042

224,042

90,824

455,409

29,810

858

190,716

8,240

Boston Properties Limited Partnership | 2600 Tower Oaks Boulevard [Member]

87,392

345,717

109,015

Revenues

$ 757,501

$ 743,553

$ 733,741

725,767

$ 705,157

$ 686,284

$ 664,484

$ 661,151

$ 2,960,562

2,717,076

$ 2,602,076

Boston Properties Limited Partnership | One Tower Center [Member]

$ 1,500

Boston Properties Limited Partnership | 164 Lexington Road [Member]

$ 22,300

Boston Properties Limited Partnership | 325 Main Street

$ 2,600

Future Office Building [Member] | 325 Main Street

$ 9,500

Square Footage Of Signed Lease | ft²

379,000

Future Retail Building [Member] | 325 Main Street

420,000

Office Properties Under Construction [Member] | 200 West Street

41,000

126,000

1,100,000

65 years

5.6

$ 134,800

$ 28,200

Joint Venture Partner [Member] | Platform 16

55.00%

^[1]

55.00%

^[1]

55.00%

^[1]

$ 23,100

45.00%

[1]	This entity is a VIE (See Note 1).

Real Estate Finance Lease Liability, Maturity (Details) - USD ($)
$ in Thousands

Dec. 31, 2019

Jul. 16, 2019

Jan. 24, 2019

Capital Leased Assets [Line Items]

$ 834

5,960

10,208

9,708

^[1]

48,518

Thereafter

1,383,242

1,458,470

(1,234,428)

$ 224,042

Capital Leased Assets [Line Items]

2019

$ 17,918

2020

109,460

127,378

(4,815)

$ 122,563

2100 Pennsylvania Avenue

Capital Leased Assets [Line Items]

$ 0

3,863

8,576

8,669

1,358,518

1,379,626

(1,214,649)

Schedule of Equity Method Investments [Line Items]

$ 164,977

[1]	Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company is reasonably certain it will exercise.

Real Estate Asset Acquisition - 880 & 890 Winter Street (Details) - 880 & 890 Winter Street [Member] $ in Thousands	Aug. 27, 2019 USD ($)
Business Acquisition [Line Items]
Land	$ 29,510
Building and improvements	59,788
Tenant improvements	6,024
Net assets acquired	105,970
In-place lease intangibles
Business Acquisition [Line Items]
Lease intangibles	11,494
Above-market lease intangibles
Business Acquisition [Line Items]
Lease intangibles	246
Below-market lease intangibles
Business Acquisition [Line Items]
Lease intangibles	$ (1,092)

Real Estate Asset Acquisition - Lease Intangibles Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Aug. 27, 2019
Acquired Finite-Lived Intangible Assets [Line Items]
Period from August 27, 2019 through December 31, 2019	$ 17,536
2020	11,001
2021	5,918
2022	4,286
2023	$ 2,510
880 & 890 Winter Street [Member] \| Acquired In-Place Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Period from August 27, 2019 through December 31, 2019		$ 1,801
2020		4,485
2021		2,391
2022		1,121
2023		179
2024		60
880 & 890 Winter Street [Member] \| Acquired Above-Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Period from August 27, 2019 through December 31, 2019		28
2020		80
2021		80
2022		43
2023		15
2024		0
880 & 890 Winter Street [Member] \| Acquired Below-Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Period from August 27, 2019 through December 31, 2019		(226)
2020		(599)
2021		(237)
2022		(30)
2023		0
2024		$ 0

Deferred Charges (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Charges [Abstract]
Leasing costs, including lease related intangibles	$ 1,155,958	$ 1,191,297
Financing costs	12,728	12,796
Deferred charges, gross	1,168,686	1,204,093
Less: Accumulated amortization	(479,473)	(525,369)
Deferred charges, total	$ 689,213	$ 678,724

Deferred Charges Schedule of Acquired In-Place Lease Intangibles (Details) $ in Thousands	Dec. 31, 2019 USD ($)
Deferred Charges [Abstract]
2020	$ 17,536
2021	11,001
2022	5,918
2023	4,286
2024	$ 2,510

Investments in Unconsolidated Joint Ventures (Investments in Unconsolidated Joint Ventures) (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2019

USD ($)

ft²

Land_Parcels

Buildings

payments

Sep. 20, 2019

Sep. 05, 2019

Jun. 27, 2019

Dec. 31, 2018

USD ($)

$ 387,994

$ 503,726

Investments In Affiliates Subsidiaries Associates And Joint Ventures net

955,647

956,309

^[1]

933,223

931,219

Schedule of Equity Method Investments [Line Items]

Square 407 Limited Partnership [Member]

$ 22,400

25,100

Schedule of Equity Method Investments [Line Items]

Market Square North

50.00%

BP/CRF Metropolitan Square LLC [Member]

^[1]

$ 4,872

6,424

Schedule of Equity Method Investments [Line Items]

Metropolitan Square

20.00%

901 New York Avenue LLC [Member]

^[1]

$ 9,134

2,644

Schedule of Equity Method Investments [Line Items]

901 New York Avenue

^[2]

25.00%

WP Project Developer LLC [Member]

^[1]

$ 12,113

13,640

Schedule of Equity Method Investments [Line Items]

Wisconsin Place Land and Infrastructure

^[3]

33.30%

Annapolis Junction NFM, LLC [Member]

^[1]

$ 36,789

38,214

Schedule of Equity Method Investments [Line Items]

Annapolis Junction

^[4]

50.00%

Number of real estate properties | Buildings

^[1]

$ 25,391

25,268

Parcels of undeveloped land | Land_Parcels

540 Madison Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

540 Madison Avenue

60.00%

^[5]

60.00%

500 North Capitol Venture LLC [Member]

^[1]

$ 2,953

66,391

Schedule of Equity Method Investments [Line Items]

500 North Capitol Street, NW

30.00%

501 K Street LLC [Member]

^[1]

$ 5,439

5,026

Schedule of Equity Method Investments [Line Items]

1001 6th Street

^[6]

50.00%

Potential additonal payments to joint venture partner | payments

^[1]

$ 42,496

42,557

Minimum square footage to make a potential additional payment to joint venture partner (in sqft) | ft²

520,000

Podium Developer LLC [Member]

Schedule of Equity Method Investments [Line Items]

The Hub on Causeway - Podium

50.00%

Residential Tower Developer LLC [Member]

^[1]

$ 49,466

69,302

Schedule of Equity Method Investments [Line Items]

Hub50House

50.00%

Hotel Tower Developer LLC [Member]

^[1]

$ 55,092

47,505

Schedule of Equity Method Investments [Line Items]

The Hub on Causeway - Hotel Air Rights

50.00%

Office Tower Developer LLC [Member]

^[1]

$ 9,883

3,022

Schedule of Equity Method Investments [Line Items]

100 Causeway Street

50.00%

1265 Main Office JV LLC [Member]

^[1]

$ 56,606

23,804

Schedule of Equity Method Investments [Line Items]

1265 Main Street

50.00%

BNY Tower Holdings LLC [Member]

^[1]

$ 3,780

3,918

Schedule of Equity Method Investments [Line Items]

Dock 72

50.00%

BNYA Amenity Operator LLC [Member]

^[1]

$ 94,804

82,520

Schedule of Equity Method Investments [Line Items]

Dock 72

50.00%

CA-Colorado Center Limited Partnership [Member]

^[1]

$ 0

Schedule of Equity Method Investments [Line Items]

Colorado Center

50.00%

7750 Wisconsin Avenue LLC [Member]

^[1]

$ 252,069

253,495

Schedule of Equity Method Investments [Line Items]

7750 Wisconsin Avenue

50.00%

BP-M 3HB Venture LLC [Member]

^[1]

$ 56,247

69,724

Schedule of Equity Method Investments [Line Items]

3 Hudson Boulevard

25.00%

Schedule of Equity Method Investments [Line Items]

^[1]

$ 67,499

46,993

SMBP Venture LP [Member]

Santa Monica Business Park

55.00%

Platform 16 Holdings LP [Member]

^[1]

$ 163,937

$ 180,952

Schedule of Equity Method Investments [Line Items]

Platform 16

55.00%

^[7]

55.00%

Entity Owning Land And Infrastructure Of Project [Member]

^[1]

$ 29,501

Schedule of Equity Method Investments [Line Items]

Real estate and development in process, net

33.30%

[1]	Investments with deficit balances aggregating approximately $22.4 million and $25.1 million at December 31, 2019 and 2018, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.
[2]	The Company’s economic ownership has increased based on the achievement of certain return thresholds.
[3]	The Company’s wholly-owned subsidiary that owns Wisconsin Place Office also owns a 33.3% interest in the joint venture entity that owns the land, parking garage and infrastructure of the project.
[4]	The joint venture owns three in-service buildings and two undeveloped land parcels.
[5]	The property was sold on June 27, 2019. As of December 31, 2019, the investment is comprised of undistributed cash. See note below for additional details.
[6]	Under the joint venture agreement for this land parcel, the partner will be entitled to up to two additional payments from the venture based on increases in total entitled square footage of the project above 520,000 square feet and achieving certain project returns at stabilization.
[7]	This entity is a VIE (See Note 1).

Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($)
$ in Thousands

Dec. 31, 2019

Jan. 01, 2019

Dec. 31, 2018

ASSETS

$ 17,622,212

$ 16,752,119

Mortgage and notes payable, net

2,922,408

2,964,572

Total liabilities and equity / capital

387,994

503,726

21,284,905

20,256,477

Carying value of the Company's investment in unconsolidated joint ventures

955,647

956,309

237,394

148,640

$ 151,800

Lease liabilities - operating leases

224,042

200,180

$ 199,300

Real estate and development in process, net

ASSETS

^[1]

3,904,400

3,545,906

Other assets

502,706

543,512

Total assets

4,407,106

4,089,418

Mortgage and notes payable, net

2,218,853

2,017,609

Members'/Partners' equity

^[2]

749,675

582,006

1,438,578

1,489,803

Total liabilities and equity / capital

4,407,106

4,089,418

Company's share of equity

591,905

622,498

Basis differentials

^[3]

341,318

308,721

Carying value of the Company's investment in unconsolidated joint ventures

^[4]

933,223

931,219

383,900

12,100

Lease liabilities - operating leases

510,800

17,300

Colorado Center [Member]

Basis differentials

311,300

316,700

Schedule of Equity Method Investments [Line Items]

$ 22,400

$ 25,100

[1]	At December 31, 2019, this amount includes right of use assets - finance leases and right of use assets - operating leases totaling approximately $383.9 million and $12.1 million, respectively.
[2]	At December 31, 2019, this amount includes lease liabilities - finance leases and lease liabilities - operating leases totaling approximately $510.8 million and $17.3 million, respectively.
[3]	This amount represents the aggregate difference between the Company’s historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials result from impairments of investments, acquisitions through joint ventures with no change in control and upon the transfer of assets that were previously owned by the Company into a joint venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level. At December 31, 2019 and 2018, there was an aggregate basis differential of approximately $311.3 million and $316.7 million, respectively, between the carrying value of the Company’s investment in the joint venture that owns Colorado Center and the joint venture’s basis in the assets and liabilities, which differential (excluding land) shall be amortized over the remaining lives of the related assets and liabilities.
[4]	Investments with deficit balances aggregating approximately $22.4 million and $25.1 million at December 31, 2019 and 2018, respectively, have been reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2019

Sep. 30, 2019

Jun. 30, 2019

Mar. 31, 2019

Dec. 31, 2018

Sep. 30, 2018

Jun. 30, 2018

Mar. 31, 2018

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

$ 757,501

$ 743,553

$ 733,741

$ 725,767

$ 705,157

$ 686,284

$ 664,484

$ 661,151

$ 2,960,562

$ 2,717,076

$ 2,602,076

Expenses

1,984

1,604

668

677,764

645,649

617,547

1,914,925

1,791,579

1,693,966

709

182,356

7,663

(412,717)

(378,168)

(374,481)

651,999

712,563

562,481

Straight-line rent adjustments

46,592

2,222

11,232

58,400

51,900

54,800

Above and below market rent adjustments, net

20,900

23,800

23,500

Schedule of Equity Method Investments [Line Items]

^[1]

322,817

271,951

222,517

Expenses

Operating

122,992

106,610

90,542

1,000

102,296

103,079

^[2]

57,079

226,288

209,689

147,621

32,706

16,951

(84,409)

(71,308)

(46,371)

Company's share of net income

44,826

7,905

28,525

24,423

8,084

18,439

Basis differential

^[4]

22,169

^[3]

(5,862)

(7,207)

Straight-line rent adjustments

46,592

2,222

11,232

32,400

15,900

21,700

Metropolitan Square [Member]

Expenses

Metropolitan Square [Member] | Boston Properties, Inc. [Member]

22,400

Expenses

540 Madison Avenue [Member]

4,500

Gain on sale of real estate

47,200

Colorado Center [Member]

Straight-line rent adjustments

2,100

2,400

1,900

Above and below market rent adjustments, net

$ 1,700

$ 1,600

$ 2,900

[1]	Includes straight-line rent adjustments of approximately $32.4 million, $15.9 million and $21.7 million for the years ended December 31, 2019, 2018 and 2017, respectively.
[2]	During the year ended December 31, 2018, the joint venture that owns Metropolitan Square in Washington, DC, commenced a renovation project and recorded accelerated depreciation expense of approximately $22.4 million related to the remaining book value of the assets to be replaced. The Company’s share of the accelerated depreciation expense totaled approximately $4.5 million.
[3]	For the year ended December 31, 2019, represents the gain on sale of 540 Madison Avenue recognized by the joint venture, as described below. During 2008, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture resulting in a basis differential between the carrying value of the Company’s investment in the joint venture and the joint venture’s basis in the assets and liabilities of the property. As a result of the historical basis difference, the Company recognized a gain on sale of real estate totaling approximately $47.2 million for the year ended December 31, 2019, which consists of its share of the gain on sale reported by the joint venture as well as an adjustment for the basis differential. The gain on sale of real estate is included in Income from Unconsolidated Joint Ventures in the Company’s Consolidated Statements of Operations.
[4]	Includes straight-line rent adjustments of approximately $2.1 million, $2.4 million and $1.9 million for the years ended December 31, 2019, 2018 and 2017, respectively. Also includes net above-/below-market rent adjustments of approximately $1.7 million, $1.6 million and $2.9 million for the years ended December 31, 2019, 2018 and 2017, respectively.

Investment in unconsolidated Joint Ventures (Narrative) (Details)
$ in Thousands

3 Months Ended

12 Months Ended

Dec. 06, 2019

USD ($)

ft²

Sep. 20, 2019

USD ($)

ft²

Sep. 16, 2019

USD ($)

Sep. 05, 2019

USD ($)

ft²

Jun. 27, 2019

USD ($)

ft²

Apr. 26, 2019

USD ($)

ft²

Jan. 24, 2019

USD ($)

ft²

Dec. 31, 2019

USD ($)

Dec. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Nov. 22, 2019

ft²

Oct. 01, 2019

ft²

apartments

May 28, 2019

USD ($)

Schedule of Equity Method Investments [Line Items]

Mortgage notes payable, net

$ 2,922,408

$ 2,964,572

Annapolis Junction Building Six [Member]

87,392

$ 345,717

$ 109,015

Schedule of Equity Method Investments [Line Items]

Mortgage notes payable, net

50.00%

$ 13,000

Extension Option (in years)

Debt instrument, borrowing capacity

$ 14,300

2.00%

7750 Wisconsin Avenue [Member]

119,000

Schedule of Equity Method Investments [Line Items]

Extension Option (in years) | yr

50.00%

Proceeds from Construction Loans Payable

$ 64,500

1.25%

Construction Loan Facility Borrowing Capacity

734,000

$ 255,000

Number of extensions

The Hub on Causeway - Podium and 100 Causeway Street [Member]

Schedule of Equity Method Investments [Line Items]

Maximum proceeds from a state infrastructure development program

50.00%

$ 30,000

Net proceeds from a state infrastructure development program

$ 28,800

Hub on Causeway - Podium [Member]

Schedule of Equity Method Investments [Line Items]

Repayments of Construction Loans Payable

382,000

$ 28,800

540 Madison Avenue [Member]

Schedule of Equity Method Investments [Line Items]

60.00%

^[1]

60.00%

^[1]

1.10%

284,000

Proceeds from Sale of Equity Method Investments

$ 310,300

Loans Assumed

120,000

178,700

Gain on sale of investment in unconsolidated joint venture

$ 47,200

100 Causeway Street [Member]

Schedule of Equity Method Investments [Line Items]

Extension Option (in years) | yr

50.00%

Proceeds from Construction Loans Payable

$ 81,100

1.50%

Construction Loan Facility Borrowing Capacity

632,000

$ 400,000

Number of extensions

Schedule of Equity Method Investments [Line Items]

55.00%

^[2]

55.00%

^[2]

1,100,000

65 years

5.6

Schedule of Equity Method Investments [Line Items]

$ 28,200

Dock 72 [Member]

50.00%

Annapolis Junction building seven and eight [Member]

670,000

Schedule of Equity Method Investments [Line Items]

Mortgage notes payable, net

50.00%

$ 34,800

Extension Option (in years) | yr

Annapolis Junction Building Seven [Member]

2.35%

Number of extensions

Schedule of Equity Method Investments [Line Items]

Annapolis Junction Building Eight [Member]

127,000

Schedule of Equity Method Investments [Line Items]

Joint Venture Partner [Member] | Platform 16

126,000

Schedule of Equity Method Investments [Line Items]

45.00%

Residential Properties [Member] | Hub50House [Member]

$ 23,100

Schedule of Equity Method Investments [Line Items]

50.00%

Number of Units in Real Estate Property | apartments

320,000

440

Company's Share [Member] | 540 Madison Avenue [Member]

Schedule of Equity Method Investments [Line Items]

Proceeds from Sale of Equity Method Investments

$ 107,100

Stabilization as defined in the agreement [Member] | 100 Causeway Street [Member]

Schedule of Equity Method Investments [Line Items]

1.375%

[1]	The property was sold on June 27, 2019. As of December 31, 2019, the investment is comprised of undistributed cash. See note below for additional details.
[2]	This entity is a VIE (See Note 1).

Mortgage Notes Payable, Net Schedule Of Aggregate Principal Payments On Mortgage Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Mortgage Notes Payable [Abstract]
2020	$ 17,168
2021	17,276
2022	614,710
2023	0
2024	0
Thereafter	2,300,000
Total	2,949,154
Deferred finance costs, net	(26,746)
Total carrying value of mortgage notes payable, net	$ 2,922,408	$ 2,964,572

Mortgage Notes Payable, Net (Narrative) (Details) $ in Thousands		12 Months Ended
	Dec. 19, 2019 USD ($) ft²	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Mortgage Notes Payable [Line Items]
Mortgage notes payable, net (amounts related to VIEs of $2,918,806 and $2,929,326 at December 31, 2019 and 2018, respectively)		$ 2,922,408	$ 2,964,572
Number Of Mortgage Loans Accounted For Fair Value		0	0
Repayments of Secured Debt		$ 46,173	$ 18,634	$ 1,317,653
Losses (gains) from early extinguishments of debt		29,540	16,490	(496)
Payment for Debt Extinguishment or Debt Prepayment Cost		$ 28,716	15,973	12,784
Interest Expense Decrease Due To Recording Mortgage Loans At Fair Value				$ 19,600
Minimum [Member]
Mortgage Notes Payable [Line Items]
Number Real Estate Assets Used For Mortgage Loan Collateral		1
Fixed Rate Mortgages [Member]
Mortgage Notes Payable [Line Items]
Mortgage notes payable, net (amounts related to VIEs of $2,918,806 and $2,929,326 at December 31, 2019 and 2018, respectively)		$ 2,900,000	$ 3,000,000
Debt, Weighted Average Interest Rate		3.73%	3.77%
Fixed Rate Mortgages [Member] \| Minimum [Member]
Mortgage Notes Payable [Line Items]
Coupon/Stated Rate		3.43%	3.43%
Fixed Rate Mortgages [Member] \| Maximum [Member]
Mortgage Notes Payable [Line Items]
Coupon/Stated Rate		6.94%	7.69%
Variable Rate Mortgages [Member]
Mortgage Notes Payable [Line Items]
Number of variable rate mortgage loans		0	0
New Dominion Technology Park, Bldg. One [Member]
Mortgage Notes Payable [Line Items]
Coupon/Stated Rate	7.69%
Repayments of Secured Debt	$ 26,500
Losses (gains) from early extinguishments of debt	1,500
Payment for Debt Extinguishment or Debt Prepayment Cost	$ 1,400
Net Rentable Area (in sf) \| ft²	235,000

Unsecured Senior Notes Schedule of Unsecured Senior Notes (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Sep. 03, 2019

Jun. 21, 2019

Dec. 31, 2018

Deferred finance costs, net

$ (26,746)

8,390,459

$ 7,544,697

Deferred finance costs, net

(26,700)

Boston Properties Limited Partnership | Senior Notes [Member]

8,390,459

$ 7,544,697

Deferred finance costs, net

8,450,000

Net unamortized discount

(17,451)

(42,090)

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Notes 4.289%

$ 8,390,459

4.125%

^[1]

4.289%

$ 850,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Notes 3.954%

^[2]

May 15, 2021

3.85%

^[1]

3.954%

$ 1,000,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Notes 3.279%

^[2]

Feb. 01, 2023

3.125%

^[1]

3.279%

$ 500,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Notes 3.916%

^[2]

Sep. 01, 2023

3.80%

^[1]

3.916%

$ 700,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Notes 3.35%

^[2]

Feb. 01, 2024

3.20%

^[1]

3.35%

$ 850,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 3.766%

^[2]

Jan. 15, 2025

3.65%

^[1]

3.766%

$ 1,000,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 3.495%

^[2]

Feb. 01, 2026

2.75%

^[1]

3.495%

$ 1,000,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 4.628%

^[2]

Oct. 01, 2026

4.50%

^[1]

4.628%

$ 1,000,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 3.505%

^[2]

Dec. 01, 2028

3.40%

3.505%

^[1]

3.505%

$ 850,000

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 2.984%

^[2]

Jun. 21, 2029

2.90%

2.984%

^[1]

2.984%

$ 700,000

^[2]

Mar. 15, 2030

[1]	Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.
[2]	No principal amounts are due prior to maturity.

Unsecured Senior Notes Unsecured Senior Notes (Narrative) (Details) - USD ($)
$ in Thousands

12 Months Ended

Sep. 18, 2019

Sep. 03, 2019

Jun. 21, 2019

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Redemption of unsecured senior notes

$ 1,548,106

$ 996,410

$ 847,935

699,237

699,517

848,020

Losses (gains) from early extinguishments of debt

29,540

16,490

(496)

Redemption of unsecured senior notes

1,548,106

996,410

847,935

699,237

699,517

848,020

Losses (gains) from early extinguishments of debt

29,540

$ 16,490

$ (496)

Boston Properties Limited Partnership | Senior Notes [Member]

Debt Instrument, Covenant Description

$ 8,450,000

Debt Instrument, Covenant Compliance

At December 31, 2019, Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 3.505%

$ 850,000

3.40%

99.815%

3.505%

^[1]

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 2.984%

$ 841,400

$ 700,000

2.90%

99.954%

2.984%

^[1]

Boston Properties Limited Partnership | Senior Notes [Member] | Unsecured Senior Note 5.708%

$ 693,800

Debt Instrument, Face Amount

5.625%

$ 700,000

Redemption of unsecured senior notes

740,700

Accrued and Unpaid Interest

$ 13,500

Redemption Price, Percentage

103.90%

Losses (gains) from early extinguishments of debt

$ 28,000

Redemption Premium

$ 27,300

[1]	Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.

Unsecured Credit Facility (Details) - USD ($) $ in Thousands		12 Months Ended
	Apr. 24, 2017	Dec. 31, 2019	Dec. 31, 2018	Apr. 24, 2018	Apr. 23, 2017
Line of Credit Facility [Line Items]
Unsecured term loan, net		$ 498,939	$ 498,488
Document Period End Date		Dec. 31, 2019
Long-term Line of Credit		$ 0	0
Line of Credit Facility, Covenant Compliance		At December 31, 2019, Boston Properties Limited Partnership was in compliance with each of these financial and other covenant requirements.
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 1,500,000				$ 1,000,000
Potential increase to line of credit	$ 500,000
Competitive bid quote	65.00%
Long-term Line of Credit		$ 0	0
Line of Credit Facility, Covenant Terms		Among other covenants, the 2017 Credit Facility requires that Boston Properties Limited Partnership maintain on an ongoing basis: (1) a leverage ratio not to exceed 60%, however, the leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (2) a secured debt leverage ratio not to exceed 55%, (3) a fixed charge coverage ratio of at least 1.40, (4) an unsecured debt leverage ratio not to exceed 60%, however, the unsecured debt leverage ratio may increase to no greater than 65% provided that it is reduced to 60% within one year, (5) an unsecured debt interest coverage ratio of at least 1.75 and (6) limitations on permitted investments.
Delayed Draw Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 500,000
Unsecured term loan, net				$ 500,000
Margin added to Calculated Interest Rate				0.90%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.15%
Long-term Line of Credit		$ 500,000	$ 500,000
Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Interest Rate Description	At Boston Properties Limited Partnership’s option, loans under the Revolving Facility and Delayed Draw Facility will bear interest at a rate per annum equal to (1) (a) in the case of loans denominated in Dollars, Euro or Sterling, LIBOR, and (b) in the case of loans denominated in Canadian Dollars, CDOR, in each case, plus a margin ranging from 77.5 to 155 basis points for the Revolving Commitment and 85 to 175 basis points for the Delayed Draw Facility, based on Boston Properties Limited Partnership’s credit rating or (2) an alternate base rate equal to the greatest of (x) the Administrative Agent’s prime rate, (y) the Federal Funds rate plus 0.50% or (z) LIBOR for a one-month period plus 1.00%, in each case, plus a margin ranging from 0 to 55 basis points for the Revolving Facility and 0 to 75 basis points for the Delayed Draw Facility, based on Boston Properties Limited Partnership’s credit rating.
Minimum [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.10%
Maximum [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage	0.30%
Current credit rating [Member] \| Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate		0.825%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.125%
Current credit rating [Member] \| Delayed Draw Facility [Member]
Line of Credit Facility [Line Items]
Margin added to Calculated Interest Rate		0.90%

Commitments And Contingencies (Details)	12 Months Ended
Commitments And Contingencies (Details)	Dec. 31, 2019 USD ($) ft²	Dec. 31, 2009 USD ($)	May 09, 2019 ft²	Apr. 26, 2019 ft²	Dec. 31, 2018 USD ($)	Jan. 10, 2014 USD ($)
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations	$ 21,000,000.0
Property insurance program per occurrence limits	1,000,000,000.0
Per occurrence limit for NBCR Coverage	1,000,000,000.0
Value of program trigger	$ 180,000,000
Coinsurance of program trigger	19.00%
Deductible in insurance as a percentage of the value of the affected property, San Francisco and Los Angeles	3.00%
Per occurrence limit of the earthquake insurance which covers San Francisco and Los Angeles regions	$ 240,000,000
Annual aggregate limit of the earthquake insurance which covers San Francisco and Los Angeles regions	240,000,000
Amount of earthquake insurance provided by IXP, LLC as direct insurer San Francisco and Los Angeles	20,000,000
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation	70,200,000
Property insurance program per occurrence limits	1,625,000,000
7750 Wisconsin Avenue [Member]
Commitments And Contingencies [Line Items]
Liabilities for Contingent Guarantees	0
Net Rentable Area (in sf) \| ft²				734,000
Lehman [Member]
Commitments And Contingencies [Line Items]
Bankruptcy claim, amount filed by general creditor		$ 45,300,000
Bankruptcy claim amount allowed by court to creditor						$ 45,200,000
Bankruptcy Claims, Amount of Claims Settled					$ 18,000,000.0
Bankruptcy remaining claim amount allowed by court to creditor	27,200,000
6595 Springfield Center Drive [Member]
Commitments And Contingencies [Line Items]
Liabilities for Contingent Guarantees	$ 0
325 Main Street
Commitments And Contingencies [Line Items]
Net Rentable Area (in sf) \| ft²	115,000		115,000
601 Lexington Avenue
Commitments And Contingencies [Line Items]
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP	$ 250,000,000
Boston Properties Limited Partnership
Commitments And Contingencies [Line Items]
Operating partnership guarantee to cover liabilities of IXP	$ 20,000,000.0
Future Residential Building [Member] \| 325 Main Street
Commitments And Contingencies [Line Items]
Net Rentable Area (in sf) \| ft²	200,000
Affordable Housing requirement	25.00%
Future Office Building [Member] \| 325 Main Street
Commitments And Contingencies [Line Items]
Net Rentable Area (in sf) \| ft²	420,000		420,000
Future Retail Building [Member] \| 325 Main Street
Commitments And Contingencies [Line Items]
Net Rentable Area (in sf) \| ft²	41,000		41,000
Home Ownership Units [Member] \| Future Residential Building [Member] \| 325 Main Street
Commitments And Contingencies [Line Items]
Affordable Housing requirement	20.00%

Noncontrolling Interests (Narrative) (Details) - Boston Properties Limited Partnership	Dec. 31, 2019 shares
Noncontrolling Interest [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Operating Partnership (OP) Units (in shares)	16,764,466
Long-Term Incentive Plan (LTIP) Units (in shares)	1,143,215
OPP Units 2012 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Outperformance awards in LTIP Units (in shares)	118,067
MYLTIP 2013
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2013 MYLTIP	68,659
MYLTIP 2014
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2014 MYLTIP	23,100
MYLTIP 2015 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2015 MYLTIP	28,724
MYLTIP 2016 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2016 MYLTIP	98,706
MYLTIP 2017 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2017 MYLTIP	394,921
MYLTIP 2018
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2018 MYLTIP	336,195
MYLTIP 2019 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2019 MYLTIPS	220,734

(Common Units) (Narrative) (Details) $ / shares in Units, $ in Thousands				12 Months Ended
	Feb. 09, 2019 USD ($) shares	Feb. 04, 2018 USD ($) shares	Feb. 03, 2017 USD ($) shares	Dec. 31, 2019 USD ($) shares yr $ / shares	Dec. 31, 2018 USD ($) shares
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares)				144,481	83,136
Redemption of OP units issued on conversion of LTIP, OPP and MYLTIP units (in shares)				92,678	48,389
MYLTIP Units distribution as percentage of OP Unit distribution prior to measurement date				10.00%
Restriction on redemption of OP Unit to Common Stock (in years) \| yr				1
Redemption of OP Unit equivalent to Common Stock (in shares)				1
Common units of operating partnership if converted value \| $				$ 2,500,000
Closing price of common stock (in dollars per share) \| $ / shares				$ 137.86
MYLTIP 2014
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target			27.70%
Value of MYLTIP Awards \| $			$ 3,500
MYLTIP Units forfeited			447,386
MYLTIP 2015 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target		22.00%
Value of MYLTIP Awards \| $		$ 3,600
MYLTIP Units forfeited		337,847
MYLTIP 2016 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target	69.50%
Value of MYLTIP Awards \| $	$ 13,600
2016 MYLTIP Units forfeited	364,980
Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Common units of operating partnership if converted value \| $				$ 2,468,753	$ 2,000,591
Boston Properties Limited Partnership \| MYLTIP 2017 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2017 MYLTIP				394,921
Boston Properties Limited Partnership \| MYLTIP 2018
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2018 MYLTIP				336,195
Boston Properties Limited Partnership \| MYLTIP 2019 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
2019 MYLTIPS				220,734

Noncontrolling Interests Common Units Distributions (Details) - Boston Properties Limited Partnership - $ / shares	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 30, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 30, 2018	Dec. 17, 2019
Dividends Payable [Line Items]
Distributions Declared To OP And LTIP Units Per Unit									$ 0.98
Distributions Declared To MYLTIP Units Per Unit									$ 0.098
Distributions made to OP and LTIP units per unit (in dollars per share)	$ 0.95	$ 0.95	$ 0.95	$ 0.95	$ 0.95	$ 0.80	$ 0.80	$ 0.80
Distributions Made To MYLTIP Units Per Unit	$ 0.095	$ 0.095	$ 0.095	$ 0.095	$ 0.095	$ 0.080	$ 0.080	$ 0.080

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) $ in Thousands			12 Months Ended
	Apr. 01, 2019 USD ($)	May 12, 2016 ft²	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 06, 2017 USD ($)
Noncontrolling Interest [Line Items]
Noncontrolling Interest in Limited Partnerships			$ 1,728,689	$ 1,711,445
Payments to Noncontrolling Interests			69,913	$ 82,501	$ 54,342
Acquisition of noncontrolling interest in property partnership			(186,963)
Salesforce Tower \| Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Portion of costs funded (in percentage)		50.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		5.00%
Debt Instrument, Basis Spread on Variable Rate		3.00%
Stabilization definition for Salesforce Tower		The term stabilization date was defined in the agreement to generally mean the first date after completion upon which Salesforce Tower is (1) at least 90% leased and (2) 50% occupied by tenants that are paying rent.
Net Rentable Area (in sf) \| ft²		1,421,000
Salesforce Tower \| Boston Properties, Inc. [Member] \| Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Costs funded (in percentage)		2.50%
Preferred equity funded			$ 22,600
Salesforce Tower
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	5.00%
Payments to Noncontrolling Interests	$ 210,900
Repayment of Preferred Equity	24,100
Net Payments To Minority Shareholders	186,800
Acquisition of noncontrolling interest in property partnership	$ 162,500
767 Fifth Avenue (the General Motors Building) [Member] \| Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest in Limited Partnerships						$ 109,600
Noncontrolling Interest, Ownership Percentage by Parent						60.00%
Unpaid principal balance of the members' notes payable contributed to equity						$ 273,900
Consolidation, Eliminations [Member] \| 767 Fifth Avenue (the General Motors Building) [Member] \| Consolidated Properties [Member]
Noncontrolling Interest [Line Items]
Unpaid principal balance of the members' notes payable contributed to equity						$ 164,400

Stockholders' Equity / Partners' Capital Narrative (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Jun. 02, 2017 USD ($) yr	Dec. 31, 2019 $ / shares shares	Dec. 31, 2018 $ / shares shares	Dec. 31, 2017 shares	Mar. 27, 2018 $ / shares	Jun. 03, 2014 USD ($)
Class of Stock [Line Items]
Common Stock, Shares, Outstanding		154,790,298	154,458,478
General Partners' Capital Account, Units Outstanding (in units)		1,726,980
Limited Partners' Capital Account, Units Outstanding (in units)		153,063,318
Options exercised		145,088	0	6,688
Shares of Common Stock issued in connection with redemption of an equal number of OP Units (in shares)		144,481	83,136
ATM Program [Member]
Class of Stock [Line Items]
At The Market Stock Offering Program Aggregate Value Of Common Stock \| $	$ 600.0					$ 600.0
At Market Stock Offering Program Maximum Length Of Sale (in years) \| yr	3
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding (in shares)		80,000	80,000
Series B, Dividend Rate, Percentage		5.25%
Series B, Liquidation Preference Per Share (dollars per share) \| $ / shares		$ 2,500.00	$ 2,500		$ 2,500.00
Depositary shares of Series B Cumulative Redeemable Preferred [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding (in shares)		8,000,000
Series B, Liquidation Preference Per Share (dollars per share) \| $ / shares		$ 25.00			$ 25.00
Boston Properties Limited Partnership
Class of Stock [Line Items]
General Partners' Capital Account, Units Outstanding (in units)		1,726,980	1,722,336
Limited Partners' Capital Account, Units Outstanding (in units)		153,063,318	152,736,142
Boston Properties Limited Partnership \| Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding (in shares)		80,000	80,000
Series B, Liquidation Preference Per Share (dollars per share) \| $ / shares		$ 2,500	$ 2,500

Stockholders' Equity / Partners' Capital Dividends / Distributions (Details) - $ / shares	Nov. 15, 2019	Oct. 31, 2019	Aug. 15, 2019	Jul. 31, 2019	May 15, 2019	Apr. 30, 2019	Feb. 15, 2019	Jan. 30, 2019	Nov. 15, 2018	Oct. 31, 2018	Aug. 15, 2018	Jul. 31, 2018	May 15, 2018	Apr. 30, 2018	Feb. 15, 2018	Jan. 30, 2018	Dec. 17, 2019
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit																	$ 0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid		$ 0.95		$ 0.95		$ 0.95		$ 0.95		$ 0.95		$ 0.80		$ 0.80		$ 0.80
Boston Properties Limited Partnership
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit																	0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid		$ 0.95		$ 0.95		$ 0.95		$ 0.95		$ 0.95		$ 0.80		$ 0.80		$ 0.80
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit																	$ 32.8125
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	$ 32.8125		$ 32.8125		$ 32.8125		$ 32.8125		$ 32.8125		$ 32.8125		$ 32.8125		$ 32.8125

Future Minimum Rents Narrative (Details) - tenants	12 Months Ended
Future Minimum Rents Narrative (Details) - tenants	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Future Minimum Rent [Line Items]
Number Of Tenants Above Concentration Amount.	0	0	0
Concentration Risk, Percentage	10.00%	10.00%	10.00%

Future Minimum Rents Future minimum rent under non-cancelable operating leases (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Future minimum rent [Abstract]
2020	$ 2,205,675	$ 2,088,171
2021	2,222,643	2,106,963
2022	2,126,968	2,015,031
2023	2,068,871	1,838,699
2024	1,974,144	1,736,636
Thereafter	$ 13,892,504	$ 12,295,464

Future Minimum Rents Future Minimum Rents for non-cancelable leases for 2018 (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Future minimum rent [Abstract]
2019	$ 2,205,675	$ 2,088,171
2020	2,222,643	2,106,963
2021	2,126,968	2,015,031
2022	2,068,871	1,838,699
2023	1,974,144	1,736,636
Thereafter	$ 13,892,504	$ 12,295,464

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Net income attributable to the Company's common shareholders / unitholders

$ 511,034

$ 572,347

$ 451,939

Noncontrolling interest-common units of the Operating Partnership

(10,500)

(59,345)

(66,807)

(52,210)

(71,120)

(62,909)

(47,832)

(412,717)

(378,168)

(374,481)

Company's share of net operating income from joint ventures

29,540

16,490

(496)

(1,826,123)

(1,649,314)

(1,605,435)

(677,764)

(645,649)

(617,547)

(1,984)

(1,604)

(668)

(140,777)

(121,722)

(113,715)

(6,417)

1,865

(3,678)

(18,939)

(10,823)

(5,783)

Business Intersegment, Eliminations [Member]

(46,592)

(2,222)

(11,232)

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Net income attributable to the Company's common shareholders / unitholders

511,034

572,347

451,939

Noncontrolling interest-common units of the Operating Partnership

10,500

59,345

66,807

52,210

71,120

62,909

47,832

412,717

378,168

374,481

29,540

16,490

(496)

24,038

11,812

677,764

645,649

617,547

1,984

1,604

668

10,386

9,590

140,777

121,722

113,715

6,417

(1,865)

3,678

18,939

10,823

5,783

709

182,356

7,663

46,592

2,222

11,232

10,386

9,590

1,739,850

1,551,842

1,495,198

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Net income attributable to the Company's common shareholders / unitholders

580,102

656,903

512,866

(10,500)

(71,120)

(62,909)

(47,832)

(412,717)

(378,168)

(374,481)

29,540

16,490

(496)

(669,956)

(637,891)

(1,984)

(1,604)

(668)

(140,777)

(121,722)

(113,715)

(6,417)

1,865

(3,678)

(18,939)

(10,823)

(5,783)

Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]

(46,592)

(2,222)

(11,232)

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Net income attributable to the Company's common shareholders / unitholders

580,102

656,903

512,866

10,500

71,120

62,909

47,832

412,717

378,168

374,481

29,540

16,490

496

22,272

10,181

669,956

637,891

609,407

1,984

1,604

668

10,386

9,590

140,777

121,722

113,715

6,417

(1,865)

3,678

18,939

10,823

5,783

858

190,716

8,240

46,592

2,222

11,232

10,386

9,590

1,739,850

1,551,842

1,495,198

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Company's share of net operating income from joint ventures

(84,409)

(71,308)

(46,371)

(97,716)

(79,893)

(64,008)

(102,296)

(103,079)

^[1]

(57,079)

(1,000)

Unconsolidated Joint Ventures [Member] | Business Intersegment, Eliminations [Member]

(46,592)

(2,222)

(11,232)

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Company's share of net operating income from joint ventures

(97,716)

(79,893)

(64,008)

Unconsolidated Joint Ventures [Member] | Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Company's share of net operating income from joint ventures

(97,716)

(79,893)

(64,008)

Management Service [Member]

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

(10,386)

(9,590)

Management Service [Member] | Business Intersegment, Eliminations [Member]

(40,039)

(45,158)

(34,605)

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Management Service [Member] | Boston Properties Limited Partnership

40,039

45,158

34,605

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

(10,386)

(9,590)

Management Service [Member] | Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]

(40,039)

(45,158)

(34,605)

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Noncontrolling interest - property partnerships [Member]

40,039

45,158

34,605

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Company's share of net operating income from joint ventures

183,989

177,365

174,245

Noncontrolling interest - property partnerships [Member] | Business Intersegment, Eliminations [Member]

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Company's share of net operating income from joint ventures

183,989

177,365

174,245

Noncontrolling interest - property partnerships [Member] | Boston Properties Limited Partnership | Business Intersegment, Eliminations [Member]

Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]

Company's share of net operating income from joint ventures

$ 183,989

$ 177,365

$ 174,245

[1]

During the year ended December 31, 2018, the joint venture that owns Metropolitan Square in Washington, DC, commenced a renovation project and recorded accelerated depreciation expense of approximately $22.4 million related to the remaining book value of the assets to be replaced. The Company’s share of the accelerated depreciation expense totaled approximately $4.5 million.

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2017

^[1]

$ 2,824,634

$ 2,590,659

$ 2,505,272

^[1]

36,914

22,551

16,596

^[1]

$ 2,910,137

$ 2,662,328

$ 2,567,471

^[1]

100.00%

$ 1,034,025

$ 966,547

$ 923,675

15,985

12,604

6,302

$ 1,084,014

$ 1,013,014

$ 962,036

100.00%

100.00%

Company's Share of Net Operating Income: % of Grand Totals

$ 1,826,123

$ 1,649,314

$ 1,605,435

100.00%

Boston [Member]

^[1]

$ 895,098

$ 838,341

$ 776,279

^[1]

13,786

6,694

4,745

^[1]

$ 957,473

$ 894,153

$ 826,627

^[1]

32.90%

33.59%

32.20%

$ 322,282

$ 315,653

$ 301,097

5,071

3,632

2,044

$ 361,357

$ 353,148

$ 335,200

33.34%

34.86%

34.84%

32.64%

32.80%

30.61%

Company's Share of Net Operating Income: % of Grand Totals

$ 596,116

$ 541,005

$ 491,427

32.27%

32.86%

30.87%

Los Angeles [Member]

^[1]

$ 0

^[1]

^[1]

$ 0

^[1]

0.00%

$ 0

$ 0

0.00%

0.00%

Company's Share of Net Operating Income: % of Grand Totals

$ 0

3.53%

2.75%

1.79%

New York [Member]

^[1]

$ 1,011,912

$ 959,050

$ 969,371

^[1]

^[1]

$ 1,011,912

$ 959,050

$ 969,371

^[1]

34.78%

36.02%

37.75%

$ 389,532

$ 377,992

$ 372,810

$ 389,532

$ 377,992

$ 372,810

35.93%

37.32%

38.76%

34.09%

35.23%

37.15%

Company's Share of Net Operating Income: % of Grand Totals

$ 622,380

$ 581,058

$ 596,561

27.77%

28.63%

30.94%

San Francisco [Member]

^[1]

$ 533,189

$ 397,180

$ 345,519

^[1]

^[1]

$ 533,189

$ 397,180

$ 345,519

^[1]

18.32%

14.92%

13.46%

$ 177,994

$ 130,016

$ 105,253

$ 177,994

$ 130,016

$ 105,253

16.42%

12.83%

10.94%

19.45%

16.20%

14.97%

Company's Share of Net Operating Income: % of Grand Totals

$ 355,195

$ 267,164

$ 240,266

20.39%

17.22%

16.10%

Washington, DC [Member]

^[1]

$ 384,435

$ 396,088

$ 414,103

^[1]

23,128

15,857

11,851

^[1]

$ 407,563

$ 411,945

$ 425,954

^[1]

14.00%

15.47%

16.59%

$ 144,217

$ 142,886

$ 144,515

10,914

8,972

4,258

$ 155,131

$ 151,858

$ 148,773

14.31%

14.99%

15.46%

13.82%

15.77%

17.27%

Company's Share of Net Operating Income: % of Grand Totals

$ 252,432

$ 260,087

$ 277,181

16.04%

18.54%

20.30%

Hotel [Member]

Hotel [Member] | Boston [Member]

^[1]

$ 48,589

$ 49,118

$ 45,603

34,004

33,863

32,059

Hotel [Member] | Los Angeles [Member]

^[1]

48,589

49,118

45,603

34,004

33,863

32,059

Hotel [Member] | New York [Member]

^[1]

Hotel [Member] | San Francisco [Member]

^[1]

Hotel [Member] | Washington, DC [Member]

^[1]

Noncontrolling interest - property partnerships [Member]

^[1]

Noncontrolling interest - property partnerships [Member] | Boston [Member]

(183,989)

(177,365)

(174,245)

Noncontrolling interest - property partnerships [Member] | Los Angeles [Member]

(40,109)

(33,862)

(31,857)

Noncontrolling interest - property partnerships [Member] | New York [Member]

Noncontrolling interest - property partnerships [Member] | San Francisco [Member]

(143,432)

(143,562)

(142,916)

Noncontrolling interest - property partnerships [Member] | Washington, DC [Member]

(448)

528

Unconsolidated Joint Ventures [Member] | Boston [Member]

97,716

79,893

64,008

Unconsolidated Joint Ventures [Member] | Los Angeles [Member]

5,494

2,866

1,962

Unconsolidated Joint Ventures [Member] | New York [Member]

61,338

42,750

26,816

Unconsolidated Joint Ventures [Member] | San Francisco [Member]

4,174

6,590

8,832

Unconsolidated Joint Ventures [Member] | Washington, DC [Member]

26,710

27,687

26,398

Company's Share [Member]

Company's Share [Member] | Boston [Member]

1,739,850

1,551,842

1,495,198

Company's Share [Member] | Los Angeles [Member]

561,501

510,009

461,532

Company's Share [Member] | New York [Member]

61,338

42,750

26,816

Company's Share [Member] | San Francisco [Member]

483,122

444,086

462,477

Company's Share [Member] | Washington, DC [Member]

354,747

267,223

240,794

$ 279,142

$ 287,774

$ 303,579

[1]	Rental Revenue is equal to Total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

Segment Information Narrative (Details) - Los Angeles [Member] ft² in Millions	Dec. 31, 2019 ft² Buildings
Segment Reporting Information [Line Items]
Number of real estate properties \| Buildings	27
Net Rentable Area (in sf) \| ft²	2.3

Earnings Per Share / Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic Earnings:
Net income attributable to the company's common shareholders / unitholders									$ 511,034	$ 572,347	$ 451,939
Net income attributable to the company's common shareholders / unitholders (in shares / units)									154,582,000	154,427,000	154,190,000
Net income attributable to the company's common shareholders / unitholders (in dollars per share / unit)	$ 0.91	$ 0.70	$ 1.06	$ 0.63	$ 0.96	$ 0.77	$ 0.83	$ 1.14	$ 3.31	$ 3.71	$ 2.93
Allocation of undistributed earnings to participating securities										$ (101)
Allocation of undistributed earnings to participating securities (in shares / units)										0
Allocation of undistributed earnings to participating securities (in dollars per share / unit)										$ 0
Net income attributable to the company's common shareholders / unitholders, after allocation of undistributed earnings to participating securities										$ 572,246
Net income attributable to the company's common shareholders / unitholders, after allocation of undistributed earnings to participating securities (in shares / units)										154,427,000
Net income attributable to the company's common shareholders / unitholders, after allocation of undistributed earnings to participating securities (in dollars per share / unit)										$ 3.71
Effect of Dilutive Securities:
Stock Based Compensation									$ 0	$ 0	$ 0
Stock Based Compensation (in shares / units)									301,000	255,000	200,000
Weighted Average Number Diluted Shares Outstanding Adjustment (per share)									$ (0.01)	$ (0.01)	$ 0
Diluted Earnings:
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders									$ 511,034	$ 572,246	$ 451,939
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders (in shares / units)									154,883,000	154,682,000	154,390,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	0.91	0.70	1.06	0.63	0.96	0.77	0.83	1.14	$ 3.30	$ 3.70	$ 2.93
Boston Properties Limited Partnership
Redeemable Common Units									17,618,000	17,485,000	17,471,000
Basic Earnings:
Net income attributable to the company's common shareholders / unitholders									$ 580,102	$ 656,903	$ 512,866
Net income attributable to the company's common shareholders / unitholders (in shares / units)									172,200,000	171,912,000	171,661,000
Net income attributable to the company's common shareholders / unitholders (in dollars per share / unit)	0.92	0.71	1.08	0.66	1.01	0.79	0.85	1.17	$ 3.37	$ 3.82	$ 2.99
Allocation of undistributed earnings to participating securities										$ (113)
Allocation of undistributed earnings to participating securities (in shares / units)										0
Allocation of undistributed earnings to participating securities (in dollars per share / unit)										$ 0
Net income attributable to the company's common shareholders / unitholders, after allocation of undistributed earnings to participating securities										$ 656,790
Net income attributable to the company's common shareholders / unitholders, after allocation of undistributed earnings to participating securities (in shares / units)										171,912,000
Net income attributable to the company's common shareholders / unitholders, after allocation of undistributed earnings to participating securities (in dollars per share / unit)										$ 3.82
Effect of Dilutive Securities:
Stock Based Compensation									$ 0	$ 0	$ 0
Stock Based Compensation (in shares / units)									301,000	255,000	200,000
Weighted Average Number Diluted Shares Outstanding Adjustment (per share)									$ (0.01)	$ (0.01)	$ (0.01)
Diluted Earnings:
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders									$ 580,102	$ 656,790	$ 512,866
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders (in shares / units)									172,501,000	172,167,000	171,861,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 0.92	$ 0.71	$ 1.08	$ 0.66	$ 1.01	$ 0.79	$ 0.85	$ 1.17	$ 3.36	$ 3.81	$ 2.98

Employee Benefit Plans (Details) - USD ($)	12 Months Ended			240 Months Ended
Employee Benefit Plans (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Related Party Transaction [Line Items]
Employer Matching Contribution, Percent of Match	200.00%
Employer Matching Contribution, Percent of Employees' Gross Pay				3.00%
Maximum Eligible Earnings As Established By IRS For Matching Contributions	$ 280,000	$ 275,000	$ 270,000
Employer Contribution Amount	4,200,000	4,100,000	$ 4,100,000
Separate Unrestricted Cash For Deferred Compensation Plans	36,700,000	28,200,000		$ 36,700,000
Deferred Compensation Liability	36,000,000.0	28,200,000		36,000,000.0
Officer [Member]
Related Party Transaction [Line Items]
Separate Unrestricted Cash For Deferred Compensation Plans	$ 36,000,000.0	$ 28,200,000		$ 36,000,000.0

Stock Option and Incentive Plan (Narrative) (Details) $ / shares in Units, $ in Millions	Feb. 09, 2019 USD ($) shares	Feb. 05, 2019 USD ($) shares	Feb. 04, 2018 USD ($) shares	Feb. 03, 2017 USD ($) shares	May 15, 2012 shares	Dec. 31, 2018 $ / shares shares	Dec. 31, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number Exercisable						540,441	540,441
Exercisable, Weighted Average Exercise Price \| $ / shares						$ 96.35	$ 96.35
2012 Stock Option and Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Additional Shares Authorized					13,000,000
Other Than Stock Options Awards Conversion Ratio					2.32
Stock Option Awards Conversion Ratio					1.0
Stock Option and Incentive Plan Term Period					10 years
MYLTIP 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		4 years
TSR measurement (in years)		three-year
Minimum earned awards		0
Maximum Earned Awards		220,734
Earned wards - Target		110,367
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights		Earned awards (if any) will vest 50% on February 4, 2022 and 50% on February 4, 2023, based on continued employment. Vesting will be accelerated in the event of a change in control, termination of employment by Boston Properties, Inc. without cause, or termination of employment by the award recipient for good reason, death, disability or retirement. If there is a change of control prior to February 4, 2022, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2019 MYLTIP awards are in the form of LTIP Units issued on the grant date which (i) are subject to forfeiture to the extent awards are not earned and (ii) prior to the performance measurement date are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units.
Value of MYLTIP Awards \| $		$ 13.5
MYLTIP Value Amortized Into Earnings, Years		four year
MYLTIP 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards \| $				$ 3.5
Final awards percentage of target				27.70%
MYLTIP Units forfeited				447,386
MYLTIP 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards \| $	$ 13.6
Stock Issued During Period, Shares, Share-based Compensation, Forfeited	364,980
Final awards percentage of target	69.50%
MYLTIP 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards \| $			$ 3.6
Final awards percentage of target			22.00%
MYLTIP Units forfeited			337,847

Stock Option and Incentive Plan (Restricted Stock) (Narrative) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) d $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued	154,869,198	154,537,378
Stock based compensation expense \| $	$ 39,800		$ 33,200
Common Stock, Value, Issued \| $	1,548	$ 1,545
Intrinsic Value of stock options \| $	$ 16,400
Number Exercisable		540,441	540,441
Exercisable, Weighted Average Exercise Price \| $ / shares		$ 96.35	$ 96.35
Non-qualified stock options issued	0	0	0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued	26,503	20,320	37,414
Employee and director payment per share (in dollars per share) \| $ / shares	$ 0.01
Common Stock, Value, Issued \| $	$ 3,500	$ 2,400	$ 4,900
Common Stock Weighted Average Price (in dollars per share) \| $ / shares	$ 131.27	$ 119.27	$ 130.32
LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value Of LTIP Units Issued \| $	$ 22,100	$ 22,700	$ 13,600
Weighted Average Per Unit Fair Value (in dollars per share) \| $ / shares	$ 121.50	$ 110.29	$ 119.41
Expected life assumed to calculate per unit fair value per LTIP unit (in years)	5 years 8 months 12 days	5 years 8 months 12 days	5 years 8 months 12 days
Risk-free rate	2.68%	2.63%	2.14%
Expected price volatility	27.00%	27.00%	28.00%
LTIP and MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share) \| $ / shares	$ 0.25
Unvested Restricted stock and LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses \| $	$ 23,300
Unvested 2017 - 2019 MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses \| $	$ 12,400
Weighted-average period (years)	2 years 4 months 24 days
Non-Qualified Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance	250,000
Payment Award Discount From Market Price Based on Ten Business Day Average	85.00%
Number Of Days Used In Calculation, Average Closing Prices Of Common Stock \| d	10
Number of shares issued	5,862	6,268	6,317
Weighted Average Purchase Price of Shares (in dollars per share) \| $ / shares	$ 104.11	$ 107.20	$ 105.97
Boston Properties Limited Partnership \| LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares)	181,919	205,838	113,918
Boston Properties Limited Partnership \| MYLTIP 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued (in shares)	220,734
Boston Properties Limited Partnership \| MYLTIP 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued (in shares)		342,659
Boston Properties Limited Partnership \| MYLTIP 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
MYLTIP units issued (in shares)			400,000

Stock Option and Incentive Plan Schedule of Stock Options Status (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Beginning Outstanding, Shares	540,441	540,441	547,129
Beginning Outstanding, Weighted Average Exercise Price	$ 96.35	$ 96.35	$ 96.38
Exercised, Shares	(145,088)	0	(6,688)
Exercised, Weighted Averge Exercise Price	$ 96.27	$ 0	$ 99.15
Ending Outstanding, Shares	395,353	540,441	540,441
Ending Outstanding, Weighted Average Exercise Price	$ 96.37	$ 96.35	$ 96.35

Stock Option and Incentive Plan Schedule of Stock Options Outstanding (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding at period end	395,353	540,441	540,441	547,129
Outstanding, Weighted Average Exercise Price	$ 96.37	$ 96.35	$ 96.35	$ 96.38
Number Exercisable		540,441	540,441
Exercisable, Weighted Average Exercise Price		$ 96.35	$ 96.35
Exercise Price of $86.86 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding at period end	81,458
Weighted Average Remaining Contractual Life (Years)	1 year 1 month 6 days
Outstanding, Weighted Average Exercise Price	$ 86.86
Number Exercisable	81,458
Exercisable, Weighted Average Exercise Price	$ 86.86
Exercise Price of $95.69 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding at period end	54,282
Weighted Average Remaining Contractual Life (Years)	3 years 3 months 18 days
Outstanding, Weighted Average Exercise Price	$ 95.69
Number Exercisable	54,282
Exercisable, Weighted Average Exercise Price	$ 95.69
Exercise Price of $98.46 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding at period end	142,422
Weighted Average Remaining Contractual Life (Years)	3 years 1 month 6 days
Outstanding, Weighted Average Exercise Price	$ 98.46
Number Exercisable	142,422
Exercisable, Weighted Average Exercise Price	$ 98.46
Exercise Price of $100.77 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number Outstanding at period end	117,191
Weighted Average Remaining Contractual Life (Years)	2 years 1 month 6 days
Outstanding, Weighted Average Exercise Price	$ 100.77
Number Exercisable	117,191
Exercisable, Weighted Average Exercise Price	$ 100.77

Related Party Transactions (Details)		12 Months Ended
Related Party Transactions (Details)	Sep. 03, 2019 shares	Dec. 31, 2019 USD ($) nonemployeedirectors shares	Dec. 31, 2018 USD ($) shares	Dec. 31, 2017 USD ($)	May 21, 2019 shares	May 23, 2018 shares
Related Party Transaction [Line Items]
Number Of Non Employee Directors Electing To Receive Deferred Stock Units \| nonemployeedirectors		7
Shares issued \| shares		154,869,198	154,537,378
Deferred Stock Units Outstanding		60,676	74,966
Separate Unrestricted Cash For Deferred Compensation Plans		$ 36,700,000	$ 28,200,000
Company's liability for Directors		377,553,000	276,645,000
Brother of Senior Executive Vice President [Member]
Related Party Transaction [Line Items]
Aggregate leasing commissions paid to related parties		21,000	$ 921,000	$ 368,000
deferred compenstation for directors [Member]
Related Party Transaction [Line Items]
Separate Unrestricted Cash For Deferred Compensation Plans		700,000
Company's liability for Directors		$ 700,000
Director Cessation [Member]
Related Party Transaction [Line Items]
Shares issued \| shares					17,949	36,836
Common Stock converted (Shares) \| shares	4,917

Selected Interim Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total revenue	$ 757,501	$ 743,553	$ 733,741	$ 725,767	$ 705,157	$ 686,284	$ 664,484	$ 661,151	$ 2,960,562	$ 2,717,076	$ 2,602,076
Net income	176,009	141,370	203,461	131,159	185,241	150,445	160,565	216,312
Net income attributable to the Company	$ 140,824	$ 107,771	$ 164,318	$ 98,105	$ 148,529	$ 119,118	$ 128,681	$ 176,021	$ 521,534	$ 582,847	$ 462,439
Income attributable to the Company (in dollars per share / unit) - Basic	$ 0.91	$ 0.70	$ 1.06	$ 0.63	$ 0.96	$ 0.77	$ 0.83	$ 1.14	$ 3.31	$ 3.71	$ 2.93
Income attributable to the Company (in dollars per share / unit) - Diluted	$ 0.91	$ 0.70	$ 1.06	$ 0.63	$ 0.96	$ 0.77	$ 0.83	$ 1.14	$ 3.30	$ 3.70	$ 2.93
Boston Properties Limited Partnership
Total revenue	$ 757,501	$ 743,553	$ 733,741	$ 725,767	$ 705,157	$ 686,284	$ 664,484	$ 661,151	$ 2,960,562	$ 2,717,076	$ 2,602,076
Net income	177,851	143,212	205,822	134,837	192,884	153,676	162,986	220,766
Net income attributable to the Company	$ 158,888	$ 122,117	$ 185,715	$ 113,382	$ 173,834	$ 136,201	$ 145,961	$ 200,907	$ 590,602	$ 667,403	$ 523,366
Income attributable to the Company (in dollars per share / unit) - Basic	$ 0.92	$ 0.71	$ 1.08	$ 0.66	$ 1.01	$ 0.79	$ 0.85	$ 1.17	$ 3.37	$ 3.82	$ 2.99
Income attributable to the Company (in dollars per share / unit) - Diluted	$ 0.92	$ 0.71	$ 1.08	$ 0.66	$ 1.01	$ 0.79	$ 0.85	$ 1.17	$ 3.36	$ 3.81	$ 2.98

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

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+ Details

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Subsequent Events (Details)
$ in Thousands

12 Months Ended

Feb. 20, 2020

USD ($)

ft²

Buildings

Feb. 06, 2020

USD ($)

Feb. 04, 2020

USD ($)

Jan. 28, 2020

USD ($)

ft²

Buildings

Sep. 20, 2019

USD ($)

ft²

Dec. 31, 2019

USD ($)

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Jan. 31, 2020

Common stock, shares issued | shares

154,869,198

154,537,378

$ 87,392

$ 345,717

$ 109,015

MYLTIPS 2020 [Member]

MYLTIP Value Amortized Into Earnings, Years

four-year

Value of MYTIP to be recognized as expense during the first year of issuance

$ 7,900

Subsequent Event [Member] | MYLTIPS 2020 [Member]

Subsequent Event [Member] | MYLTIPS 2020 [Member] | NAREIT Office Index adjusted [Member]

Value of MYLTIP Awards

$ 13,700

Subsequent Event [Member] | MYLTIP 2017 [Member]

Target Tier | shares

101,638

Final awards percentage of target

Value of MYLTIP Awards

$ 17,600

83.80%

MYLTIP Units forfeited | shares

270,942

Subsequent Event [Member] | Minimum [Member] | MYLTIPS 2020 [Member] | NAREIT Office Index adjusted [Member]

Minimum earned awards | shares

Subsequent Event [Member] | Maximum [Member] | MYLTIPS 2020 [Member] | NAREIT Office Index adjusted [Member]

Maximum Earned Awards | shares

203,278

Subsequent Event [Member] | Restricted Stock [Member]

Common stock, shares issued | shares

24,503

Subsequent Event [Member] | LTIP Units [Member]

LTIP units issued (in shares) | shares

196,927

New Dominion Technology Park [Member] | Subsequent Event [Member]

number of buildings | Buildings

$ 256,000

Gateway Commons Complex [Member] | Subsequent Event [Member]

493,000

number of buildings | Buildings

50.00%

768,000

$ 350,000

55.00%

^[1]

1,100,000

$ 134,800

5.6

Platform 16 | Subsequent Event [Member]

$ 28,200

55.00%

1,100,000

$ 134,800

Prepaid purchase price

$ 15,000

Joint Venture Partner [Member] | Gateway Commons Complex [Member] | Subsequent Event [Member]

5.6

number of buildings | Buildings

50.00%

Future payment to acquire interest in equity method investment

$ 280,800

$ 69,200

Joint Venture Partner [Member] | Platform 16

45.00%

425 Fourth Street | Subsequent Event [Member]

$ 23,100

Future Office Building [Member] | Platform 16 | Subsequent Event [Member]

804,000

Aggregate purchase price

$ 134,100