0001656423-21-000013 | 10-Q | XBRL Viewer

General and administrative

713,695

752,556

Expenses

Rental

257,389

262,966

44,959

36,454

331

615

176,565

171,094

484,800

481,187

Income (Loss) from Unconsolidated Joint Ventures

5,225

(369)

Gains (losses) on sales of real estate

410,165

Interest and other income (loss)

1,168

3,017

Gains (losses) from investments in securities

1,659

(5,445)

(898)

(107,902)

(101,591)

Net (income) loss attributable to noncontrolling interests

128,147

577,146

Noncontrolling interests in property partnerships

(16,467)

(19,486)

Noncontrolling interest - common units of the Operating Partnership

(11,084)

(57,539)

Net income attributable to the Company

100,596

500,121

Preferred dividends / distributions

(2,560)

(2,625)

Preferred Stock Redemption Charge

(6,412)

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

$ 91,624

$ 497,496

Basic earnings per common share / unit attributable to the Company

Earnings Per Share After Allccation of Undistributed Earnings to Particiapting Securities Basic (dollars per share)

$ 0.59

$ 3.20

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

155,928

155,011

Diluted earnings per common share / unit attributable to the Company

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

$ 0.59

$ 3.20

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

156,099

155,258

Revenue

Lease

$ 685,817

$ 710,111

General and administrative

713,695

752,556

Expenses

Rental

257,389

262,966

44,959

36,454

331

615

173,500

169,285

481,735

479,378

Income (Loss) from Unconsolidated Joint Ventures

5,225

(369)

Gains (losses) on sales of real estate

419,654

Interest and other income (loss)

1,168

3,017

Gains (losses) from investments in securities

1,659

(5,445)

(898)

(107,902)

(101,591)

Net (income) loss attributable to noncontrolling interests

131,212

588,444

Noncontrolling interests in property partnerships

(16,467)

(19,486)

Net income attributable to the Company

114,745

568,958

Preferred dividends / distributions

(2,560)

(2,625)

Preferred Stock Redemption Charge

(6,412)

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

$ 105,773

$ 566,333

Basic earnings per common share / unit attributable to the Company

Earnings Per Share After Allccation of Undistributed Earnings to Particiapting Securities Basic (dollars per share)

$ 0.61

$ 3.28

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

173,018

172,549

Diluted earnings per common share / unit attributable to the Company

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

$ 0.61

$ 3.27

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

173,189

172,796

Parking and Other [Member]

Revenue

Parking and Other [Member] | Boston Properties Limited Partnership

$ 16,938

$ 24,504

Revenue

16,938

24,504

Hotel [Member]

Revenue

^[1]

632

6,825

Expenses

Hotel [Member] | Boston Properties Limited Partnership

2,051

6,821

Revenue

632

6,825

Expenses

Real Estate, Other [Member]

2,051

6,821

Revenue

3,505

3,237

Expenses

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

3,505

3,237

Revenue

Management Service [Member]

3,505

3,237

Revenue

Management Service [Member] | Boston Properties Limited Partnership

6,803

7,879

Revenue

6,803

7,879

Expenses

$ 3,505

$ 3,237

[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

3 Months Ended

Mar. 31, 2021

Mar. 31, 2020

Effective portion of interest rate contracts

$ 128,147

$ 577,146

Other comprehensive income (loss):

3,740

(9,720)

Amortization of interest rate contracts

^[1]

1,676

1,666

Other comprehensive income (loss)

5,416

(8,054)

Comprehensive Income

133,563

569,092

Comprehensive income attributable to noncontrolling interests

(27,551)

(77,025)

Other comprehensive (income) loss attributable to noncontrolling interests

(665)

689

Comprehensive income attributable to the Company

105,347

492,756

Effective portion of interest rate contracts

131,212

588,444

Other comprehensive income (loss):

3,740

(9,720)

Amortization of interest rate contracts

^[2]

1,676

1,666

Other comprehensive income (loss)

5,416

(8,054)

Comprehensive Income

136,628

580,390

Comprehensive income attributable to noncontrolling interests

(16,611)

(19,630)

Comprehensive income attributable to the Company

$ 120,017

$ 560,760

[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 Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-In Capital [Member]	Dividends In Excess Of Earnings [Member]	Dividends In Excess Of Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment	Treasury Stock, at cost [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]	Noncontrolling Interests [Member] Cumulative Effect, Period of Adoption, Adjustment	Noncontrolling interest - property partnerships [Member]
Equity, shares at Dec. 31, 2019			154,790,000
Equity, value at Dec. 31, 2019	$ 8,014,236	$ (1,679)	$ 1,548	$ 200,000	$ 6,294,719	$ (760,523)	$ (1,505)	$ (2,722)	$ (48,335)	$ 600,860	$ (174)	$ 1,728,689
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock, shares			462,000
Redemption of operating partnership units to common stock, value	0		$ 5		15,490					(15,495)
Allocated net income for the year	577,146					500,121				57,539		19,486
Dividends/distributions declared	(172,277)					(154,833)				(17,444)
Shares issued pursuant to stock purchase plan, shares			2,000
Shares issued pursuant to stock purchase plan, value	325				325
Net activity from stock option and incentive plan, shares			61,000
Net activity from stock option and incentive plan, value	23,060				7,383					15,677
Preferred Stock Redemption Charge	0
Contributions from noncontrolling interests in property partnerships	3,876											3,876
Distributions to noncontrolling interests in property partnerships	(15,750)											(15,750)
Effective portion of interest rate contracts	(9,720)								(8,732)	(988)
Amortization of interest rate contracts	1,666								1,367	155		144
Reallocation of noncontrolling interest	0				3,558					(3,558)
Equity, shares at Mar. 31, 2020			155,315,000
Equity, value at Mar. 31, 2020	$ 8,420,883		$ 1,553	200,000	6,321,475	(416,740)		(2,722)	(55,700)	636,572		1,736,445
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List] \| Accounting Standards Update 2018-09	us-gaap:AccountingStandardsUpdate201809Member
Equity, shares at Dec. 31, 2020	155,718,825		155,719,000
Equity, value at Dec. 31, 2020	$ 8,339,612		$ 1,557	200,000	6,356,791	(509,653)		(2,722)	(49,890)	616,596		1,726,933
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock, shares			118,000
Redemption of operating partnership units to common stock, value	0		$ 1		4,197					(4,198)
Allocated net income for the year	128,147					100,596				11,084		16,467
Dividends/distributions declared	(172,800)					(155,513)				(17,287)
Shares issued pursuant to stock purchase plan, shares			5,000
Shares issued pursuant to stock purchase plan, value	484				484
Net activity from stock option and incentive plan, shares			232,000
Net activity from stock option and incentive plan, value	38,467		$ 3		20,002					18,462
Preferred Stock Redemption Charge	(6,412)					(6,412)
Contributions from noncontrolling interests in property partnerships	281											281
Distributions to noncontrolling interests in property partnerships	(18,225)											(18,225)
Effective portion of interest rate contracts	3,740								3,370	370		0
Amortization of interest rate contracts	1,676								1,381	151		144
Reallocation of noncontrolling interest	$ 0				5,072					(5,072)
Equity, shares at Mar. 31, 2021	156,074,200		156,074,000
Equity, value at Mar. 31, 2021	$ 8,121,347		$ 1,561	0	6,392,923	$ (570,982)		$ (2,722)	$ (45,139)	$ 620,106		$ 1,725,600
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Preferred Stock, Redemption Amount	$ (193,623)			$ (200,000)	$ (6,377)

Consolidated Statement of Capital and Noncontrolling Interests - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Common Stock, Shares, Outstanding	156,074,200		155,718,825
Effective portion of interest rate contracts	$ 3,740	$ (9,720)
Amortization of interest rate contracts	1,676	1,666
Contributions from noncontrolling interests in property partnerships	281	3,876
Distributions to noncontrolling interests in property partnerships	(18,225)	(15,750)
Preferred Stock, Redemption Amount	(193,623)
Preferred Stock Redemption Charge	(6,412)	0
Net activity from stock option and incentive plan, value	$ 38,467	$ 23,060
Accounting Standards Update 2018-09
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201809Member
General Partner [Member]
Common Stock, Shares, Outstanding	1,737,000	1,731,000	1,731,000	1,727,000
Net activity from stock option and incentive plan, shares	4,000	1,000
Conversion of redeemable partnership units	2,000	3,000
Limited Partner [Member]
Common Stock, Shares, Outstanding	154,338,000	153,584,000	153,988,000	153,063,000
Net activity from stock option and incentive plan, shares	233,000	63,000
Conversion of redeemable partnership units	117,000	458,000
Partners' Capital (General and Limited Partners)[Member]
Beginning Balance	$ 4,392,624	$ 4,626,627	$ 4,554,639	$ 3,380,175
Allocated net income for the period	101,101	508,794
Distributions	(152,953)	(152,208)
Conversion of redeemable partnership units, value	4,198	15,495
Adjustment to reflect redeemable partnership units at redemption value	(128,438)	868,168
Preferred Stock Redemption Charge	(6,412)
Net activity from stock option and incentive plan, value	20,489	7,708
Partners' Capital (General and Limited Partners)[Member] \| Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance		(1,505)
Preferred Units [Member]
Beginning Balance	0	193,623	193,623	193,623
Allocated net income for the period	2,560	2,625
Distributions	(2,560)	(2,625)
Preferred Stock, Redemption Amount	(200,000)
Preferred Units [Member] \| Boston Properties Limited Partnership
Preferred Stock, Redemption Amount	(193,623)
Accumulated Other Comprehensive Loss [Member]
Beginning Balance	(45,139)	(55,700)	(49,890)	(48,335)
Effective portion of interest rate contracts	3,370	(8,732)
Amortization of interest rate contracts	1,381	1,367
Noncontrolling interest - property partnerships [Member]
Beginning Balance	1,725,600	1,736,445	1,726,933	1,728,689
Allocated net income for the period	16,467	19,486
Effective portion of interest rate contracts	0
Amortization of interest rate contracts	144	144
Contributions from noncontrolling interests in property partnerships	281	3,876
Distributions to noncontrolling interests in property partnerships	(18,225)	(15,750)
Total Capital [Member]
Beginning Balance	6,073,085	6,500,995	6,425,305	5,254,152
Allocated net income for the period	120,128	530,905
Distributions	(155,513)	(154,833)
Conversion of redeemable partnership units, value	4,198	15,495
Adjustment to reflect redeemable partnership units at redemption value	(128,438)	868,168
Effective portion of interest rate contracts	3,370	(8,732)
Amortization of interest rate contracts	1,525	1,511
Contributions from noncontrolling interests in property partnerships	281	3,876
Distributions to noncontrolling interests in property partnerships	(18,225)	(15,750)
Preferred Stock Redemption Charge	(6,412)
Net activity from stock option and incentive plan, value	20,489	7,708
Total Capital [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance		(1,505)
Total Capital [Member] \| Boston Properties Limited Partnership
Preferred Stock, Redemption Amount	(193,623)
Noncontrolling interest - Redeemable partnership units [Member]
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	1,780,044	1,639,855	$ 1,643,024	$ 2,468,753
Allocated net income for the period	11,084	57,539
Distributions	(17,287)	(17,444)
Conversion of redeemable partnership units, value	(4,198)	(15,495)
Adjustment to reflect redeemable partnership units at redemption value	128,438	(868,168)
Effective portion of interest rate contracts	370	(988)
Amortization of interest rate contracts	151	155
Net activity from stock option and incentive plan, value	18,462	15,677
Noncontrolling interest - Redeemable partnership units [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount		$ (174)
Dividends In Excess Of Earnings [Member]
Preferred Stock Redemption Charge	$ (6,412)

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net income	$ 128,147	$ 577,146
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	176,565	171,094
Amortization of right of use assets - operating leases	2,263	583
Non-cash compensation expense	20,090	17,525
(Income) Loss from unconsolidated joint ventures	(5,225)	369
Distributions of net cash flow from operations of unconsolidated joint ventures	3,972	5,917
(Gains) losses from investments in securities	(1,659)	5,445
Allowance for current expected credit losses	(128)	0
Non-cash portion of interest expense	5,984	5,646
Settlement of accreted debt discount on redemption of unsecured senior notes	(6,290)	0
Loss from early extinguishment of debt	898	0
Gains on sales of real estate	0	(410,165)
Change in assets and liabilities:
Tenant and other receivables, net	26,020	17,784
Notes receivable, net	(140)	(128)
Accrued rental income, net	(9,413)	(27,285)
Prepaid expenses and other assets	(96,351)	(93,819)
Lease liabilities - operating leases	(1,330)	393
Accounts payable and accrued expenses	(21,578)	(48,591)
Accrued interest payable	(28,970)	(7,644)
Other liabilities	(24,177)	(21,296)
Tenant leasing costs	(16,615)	(17,777)
Total adjustments	23,916	(401,949)
Net cash provided by operating activities	152,063	175,197
Cash flows from investing activities:
Construction in progress	(119,496)	(143,160)
Building and other capital improvements	(32,717)	(39,154)
Tenant improvements	(93,201)	(64,172)
Proceeds from sales of real estate	0	259,489
Capital contributions to unconsolidated joint ventures	(16,684)	(89,997)
Capital distributions from unconsolidated joint ventures	122	0
Proceeds from sale of investment in unconsolidated joint venture	17,589	0
Investments in securities, net	2,114	3,201
Net cash used in investing activities	(242,273)	(73,793)
Cash flows from financing activities:
Repayments of mortgage notes payable	(5,374)	(4,212)
Proceeds from unsecured senior notes	846,345	0
Redemption of unsecured senior notes	(843,710)	0
Borrowings on unsecured line of credit	0	265,000
Repayments of unsecured line of credit	0	(15,000)
Repayment of unsecured term loan	500,000	0
Deferred financing costs	(7,145)	(11)
Debt prepayment and extinguishment costs	(185)	0
Net proceeds from equity transactions	19,643	3,349
Dividends and distributions	(171,566)	(171,964)
Contributions from noncontrolling interests in property partnerships	281	3,876
Distributions to noncontrolling interests in property partnerships	(18,225)	(15,750)
Net cash provided by (used in) financing activities	(679,936)	65,288
Net increase (decrease) in cash and cash equivalents and cash held in escrows	(770,146)	166,692
Cash and cash equivalents and cash held in escrows, beginning of period	1,719,329	691,886
Cash and cash equivalents and cash held in escrows, end of period	949,183	858,578
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of period	1,668,742	644,950
Cash held in escrows, beginning of period	50,587	46,936
Cash and cash equivalents, end of period	697,369	660,733
Cash held in escrows,end of period	251,814	197,845
Supplemental disclosures:
Cash paid for interest	146,781	114,696
Interest capitalized	12,032	14,149
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(25,161)	(38,782)
Change in real estate included in accounts payable and accrued expenses	(42,778)	(27,415)
Preferred stock redemption liability	200,000	0
Accrued rental income, net deconsolidated	0	(4,558)
Tenant leasing costs, net deconsolidated	0	3,462
Building and other capital improvements, net deconsolidated	0	(111,889)
Tenant improvements, net deconsolidated	0	(12,331)
Investment in unconsolidated joint venture recorded upon deconsolidation	0	347,898
Deferred distributions from sale of investment in unconsolidated joint venture	5,808	0
Deferred proceeds from sale of investment in unconsolidated joint venture	200	0
Dividends and distributions declared but not paid	171,003	171,026
Conversions of noncontrolling interests to stockholders’ equity	4,198	15,495
Issuance of restricted securities to employees and non-employee directors	41,255	43,104
Boston Properties Limited Partnership
Net income	131,212	588,444
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	173,500	169,285
Amortization of right of use assets - operating leases	2,263	583
Non-cash compensation expense	20,090	17,525
(Income) Loss from unconsolidated joint ventures	(5,225)	369
Distributions of net cash flow from operations of unconsolidated joint ventures	3,972	5,917
(Gains) losses from investments in securities	(1,659)	5,445
Allowance for current expected credit losses	(128)	0
Non-cash portion of interest expense	5,984	5,646
Settlement of accreted debt discount on redemption of unsecured senior notes	(6,290)	0
Loss from early extinguishment of debt	898	0
Gains on sales of real estate	0	(419,654)
Change in assets and liabilities:
Tenant and other receivables, net	26,020	17,784
Notes receivable, net	(140)	(128)
Accrued rental income, net	(9,413)	(27,285)
Prepaid expenses and other assets	(96,351)	(93,819)
Lease liabilities - operating leases	(1,330)	393
Accounts payable and accrued expenses	(21,578)	(48,591)
Accrued interest payable	(28,970)	(7,644)
Other liabilities	(24,177)	(21,296)
Tenant leasing costs	(16,615)	(17,777)
Total adjustments	20,851	(413,247)
Net cash provided by operating activities	152,063	175,197
Cash flows from investing activities:
Construction in progress	(119,496)	(143,160)
Building and other capital improvements	(32,717)	(39,154)
Tenant improvements	(93,201)	(64,172)
Proceeds from sales of real estate	0	259,489
Capital contributions to unconsolidated joint ventures	(16,684)	(89,997)
Capital distributions from unconsolidated joint ventures	122	0
Proceeds from sale of investment in unconsolidated joint venture	17,589	0
Investments in securities, net	2,114	3,201
Net cash used in investing activities	(242,273)	(73,793)
Cash flows from financing activities:
Repayments of mortgage notes payable	(5,374)	(4,212)
Proceeds from unsecured senior notes	846,345	0
Redemption of unsecured senior notes	(843,710)	0
Borrowings on unsecured line of credit	0	265,000
Repayments of unsecured line of credit	0	(15,000)
Repayment of unsecured term loan	(500,000)	0
Deferred financing costs	(7,145)	(11)
Debt prepayment and extinguishment costs	(185)	0
Net proceeds from equity transactions	19,643	3,349
Dividends and distributions	(171,566)	(171,964)
Contributions from noncontrolling interests in property partnerships	281	3,876
Distributions to noncontrolling interests in property partnerships	(18,225)	(15,750)
Net cash provided by (used in) financing activities	(679,936)	65,288
Net increase (decrease) in cash and cash equivalents and cash held in escrows	(770,146)	166,692
Cash and cash equivalents and cash held in escrows, beginning of period	1,719,329	691,886
Cash and cash equivalents and cash held in escrows, end of period	949,183	858,578
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of period	1,668,742	644,950
Cash held in escrows, beginning of period	50,587	46,936
Cash and cash equivalents, end of period	697,369	660,733
Cash held in escrows,end of period	251,814	197,845
Supplemental disclosures:
Cash paid for interest	146,781	114,696
Interest capitalized	12,032	14,149
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(23,847)	(38,782)
Change in real estate included in accounts payable and accrued expenses	(42,778)	(27,415)
Preferred stock redemption liability	200,000	0
Accrued rental income, net deconsolidated	0	(4,558)
Tenant leasing costs, net deconsolidated	0	(3,462)
Building and other capital improvements, net deconsolidated	0	(111,889)
Tenant improvements, net deconsolidated	0	(12,331)
Investment in unconsolidated joint venture recorded upon deconsolidation	0	347,898
Deferred distributions from sale of investment in unconsolidated joint venture	5,808	0
Deferred proceeds from sale of investment in unconsolidated joint venture	200	0
Dividends and distributions declared but not paid	171,003	171,026
Conversions of noncontrolling interests to stockholders’ equity	4,198	15,495
Issuance of restricted securities to employees and non-employee directors	$ 41,255	$ 43,104

Organization	3 Months Ended
Organization	Mar. 31, 2021
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 March 31, 2021 owned an approximate 89.9% (90.0% at December 31, 2020) 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 time-based, restricted equity compensation and as a form of performance-based equity compensation for employees, and has previously granted LTIP Units in the form of (1) 2012 outperformance plan awards (“2012 OPP Units”) and (2) 2013 - 2021 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 and the 2013 - 2018 MYLTIP Units have ended 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 2019 - 2021 MYLTIP Units differ from other LTIP Units granted to employees (including the 2012 OPP Units and the 2013 - 2018 MYLTIP Units, which have been earned). Therefore, unless specifically noted otherwise, all references to LTIP Units exclude the 2019 - 2021 MYLTIP Units. LTIP Units (including the earned 2012 OPP Units and the earned 2013 - 2018 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 and 14). At December 31, 2020, 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). On March 2, 2021, Boston Properties, Inc. issued a redemption notice for 80,000 shares of Series B Preferred Stock, which constituted all of the outstanding Series B Preferred Stock, and the corresponding depositary shares, each representing 1/100th of a share of Series B Preferred Stock (the “Depositary Shares”), and recorded it as a liability. Upon redemption of the Series B Preferred Stock, the Series B Preferred Units were also redeemed. On March 31, 2021, Boston Properties, Inc. transferred the full redemption price for all outstanding shares of Series B Preferred Stock of approximately $201.3 million, including approximately $1.3 million of accrued and unpaid dividends to, but not including, the redemption date, to the redemption agent and recorded the amount within Cash held in escrows on the Consolidated Balance Sheet (See Notes 11 and 15). Properties At March 31, 2021, the Company owned or had joint venture interests in a portfolio of 196 commercial real estate properties (the “Properties”) aggregating approximately 51.6 million net rentable square feet of primarily Class A office properties, including nine properties under construction/redevelopment totaling approximately 4.3 million net rentable square feet. At March 31, 2021, the Properties consisted of: •177 office properties (including nine properties under construction/redevelopment); •12 retail properties; •six residential properties; and •one hotel. The Company considers Class A office properties to be well-located buildings that are modern structures or have been modernized to compete with newer buildings and professionally managed and maintained. As such, these properties attract high-quality tenants and command upper-tier rental rates.

Summary Of Significant Accounting Policies

3 Months Ended

Mar. 31, 2021

Accounting Policies [Abstract]

Basis Of Presentation And Summary Of Significant Accounting Policies

2. Basis of Presentation and Summary of Significant Accounting Policies

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.

The accompanying interim financial statements are unaudited; however, the financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting solely of normal recurring matters) necessary for a fair statement of the financial statements for these interim periods have been included. The results of operations for the interim periods are not necessarily indicative of the results to be obtained for other interim periods or for the full fiscal year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosure required by GAAP. These financial statements should be read in conjunction with the Company’s financial statements and notes thereto contained in the Company’s Annual Report in the Company’s Form 10-K for its fiscal year ended December 31, 2020.

The Company bases its estimates on historical experience and on various other assumptions that it considers to be reasonable under the circumstances, including the impact of extraordinary events such as the novel coronavirus (“COVID-19”) pandemic, the results of which form the basis for making significant judgments about the carrying values of assets and liabilities, assessments of future collectability, and other areas of the financial statements that are impacted by the use of estimates. Actual results may differ from these estimates under different assumptions or conditions.

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 seven entities that are VIEs.

Consolidated Variable Interest Entities

As of March 31, 2021, 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), Times 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 (excluding Boston Properties Limited Partnership’s interest) are reflected as noncontrolling interests 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 the Platform 16 Holdings LP joint venture is a VIE. The Company does not consolidate this entity 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.

Fair Value of Financial Instruments

The Company follows the authoritative guidance for fair value measurements when valuing its financial instruments for disclosure purposes. The table below presents the financial instruments that are being valued for disclosure purposes as well as the Level at which they are categorized (as defined in Accounting Standards Codification (“ASC”) 820 “Fair Value Measurements and Disclosures” (“ASC 820”)).


Financial Instrument			Level
Unsecured senior notes (1)			Level 1
Related party note receivable			Level 3
Notes receivable			Level 3
Mortgage notes payable			Level 3
Unsecured line of credit (2)			Level 3

_______________

(1)If trading value for the period is low, the valuation could be categorized as Level 2.

(2)As of March 31, 2021, there were no amounts outstanding under the unsecured line of credit.

Because the Company’s valuations of its financial instruments are based on the above Levels and involve the use of estimates, the actual fair values of its financial instruments may differ materially from those estimates.

The following table identifies the range and weighted average of significant unobservable inputs for the Company’s Level 3 fair value measured instruments.


Financial Instrument	Level	Range	Weighted Average
Related party note receivable	Level 3	3.61%	3.61%
Notes receivable	Level 3	3.60% - 8.00%	5.85%
Mortgage notes payable	Level 3	2.75% - 3.07%	2.82%

In addition, the Company’s estimated fair values for these instruments as of the end of the applicable reporting period are not projections of, nor 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, net, notes receivable, net, 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 March 31, 2021 and December 31, 2020 (in thousands):


	March 31, 2021				December 31, 2020
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable, net	$	77,640	$	84,205	$	77,552	$	84,579
Notes receivable, net	18,891		19,541		18,729		19,372
Total	$	96,531	$	103,746	$	96,281	$	103,951

Mortgage notes payable, net	$	2,904,672	$	3,025,986	$	2,909,081	$	3,144,150
Unsecured senior notes, net	9,631,592		10,216,659		9,639,287		10,620,527
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	—		—		499,390		500,326
Total	$	12,536,264	$	13,242,645	$	13,047,758	$	14,265,003

Real Estate

3 Months Ended

Mar. 31, 2021

Real Estate [Abstract]

Real Estate

3. Real Estate

Boston Properties, Inc.

Real estate consisted of the following at March 31, 2021 and December 31, 2020 (in thousands):


	March 31, 2021		December 31, 2020
Land	$	5,068,843	$	5,069,206
Right of use assets - finance leases	237,017		237,393
Right of use assets - operating leases	144,143		146,406
Land held for future development (1)	421,349		450,954
Buildings and improvements	14,004,418		13,777,691
Tenant improvements	2,816,726		2,752,880
Furniture, fixtures and equipment	51,549		49,606
Construction in progress	794,039		868,773
Total	23,538,084		23,352,909
Less: Accumulated depreciation	(5,665,061)		(5,534,102)
	$	17,873,023	$	17,818,807

_______________

(1)Includes pre-development costs.

Boston Properties Limited Partnership

Real estate consisted of the following at March 31, 2021 and December 31, 2020 (in thousands):


	March 31, 2021		December 31, 2020
Land	$	4,971,990	$	4,971,990
Right of use assets - finance leases	237,017		237,393
Right of use assets - operating leases	144,143		146,406
Land held for future development (1)	421,349		450,954
Buildings and improvements	13,725,776		13,498,098
Tenant improvements	2,816,726		2,752,880
Furniture, fixtures and equipment	51,549		49,606
Construction in progress	794,039		868,773
Total	23,162,589		22,976,100
Less: Accumulated depreciation	(5,557,784)		(5,428,576)
	$	17,604,805	$	17,547,524

_______________

(1)Includes pre-development costs.

Developments

On February 1, 2021, the Company completed and fully placed in-service One Five Nine East 53rd Street, a Class A office and retail redevelopment of the low-rise portion of its 601 Lexington Avenue property with approximately 220,000 net rentable square feet located in New York City.

On February 25, 2021, the Company commenced the development of 180 CityPoint, located in Waltham, Massachusetts. When completed, the building will consist of approximately 329,000 net rentable square feet of laboratory space.

On February 25, 2021, the Company commenced the redevelopment of 880 Winter Street, located in Waltham, Massachusetts. When completed, the building will consist of approximately 224,000 net rentable square feet of laboratory space.

On February 25, 2021, the Company commenced the redevelopment of The Prudential Center Observatory, a 59,000 net rentable square foot redevelopment of the top three floors of 800 Boylston Street - The Prudential Center, located in Boston, Massachusetts.

Leases

3 Months Ended

Mar. 31, 2021

Leases [Abstract]

Leases of Lessor Disclosure [Text Block]

4. Leases

The Company must make estimates as to the collectability of its accrued rent and accounts receivable related to lease revenue. Management analyzes accrued rent and accounts receivable by considering tenant creditworthiness, current economic trends, including the impact of COVID-19 on tenants’ businesses, and changes in tenants’ payment patterns when evaluating the collectability of the tenant’s receivable balance, including the accrued rent receivable, on a lease-by-lease basis. As a result of this analysis, during the three months ended March 31, 2021 and 2020, the Company wrote off approximately $0.6 million and $1.2 million, respectively, related to accrued rent, net balances and approximately $(0.2) million and $0.3 million, respectively, related to accounts receivable, net balances. The write-offs were for tenants, primarily in the retail sector, that either terminated their leases or that the Company considered their accrued rent and/or accounts receivable balances no longer probable of collection.

The following table summarizes the components of lease revenue recognized during the three months ended March 31, 2021 and 2020 included within the Company's Consolidated Statements of Operations (in thousands):


	Three months ended March 31,
Lease Revenue	2021		2020
Fixed contractual payments	$	575,353	$	586,957
Variable lease payments	110,464		123,154
	$	685,817	$	710,111

Investments in Unconsolidated Joint Ventures

3 Months Ended

Mar. 31, 2021

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 March 31, 2021 and December 31, 2020:


					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			March 31, 2021		December 31, 2020
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.0	%		$	(3,293)	$	(3,766)
BP/CRF Metropolitan Square LLC	Metropolitan Square	20.0	%		(12,971)		(13,584)
901 New York, LLC	901 New York Avenue	25.0	%	(2)	(12,198)		(12,264)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.3	%	(3)	34,887		35,297
Annapolis Junction NFM LLC	Annapolis Junction	50.0	%	(4)	—		13,463
540 Madison Venture LLC	540 Madison Avenue	60.0	%	(5)	—		122
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.0	%		(7,187)		(6,945)
501 K Street LLC	1001 6th Street	50.0	%	(6)	42,607		42,499
Podium Developer LLC	The Hub on Causeway - Podium	50.0	%		48,398		48,818
Residential Tower Developer LLC	Hub50House	50.0	%		49,520		50,943
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.0	%		11,032		10,754
Office Tower Developer LLC	100 Causeway Street	50.0	%		56,458		56,312
1265 Main Office JV LLC	1265 Main Street	50.0	%		3,899		3,787
BNY Tower Holdings LLC	Dock 72	50.0	%		27,936		29,536
BNYTA Amenity Operator LLC	Dock 72	50.0	%		1,672		1,846
CA-Colorado Center Limited Partnership	Colorado Center	50.0	%		229,094		227,671
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.0	%		58,697		58,112
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.0	%		115,869		113,774
SMBP Venture LP	Santa Monica Business Park	55.0	%		159,545		145,761
Platform 16 Holdings LP	Platform 16	55.0	%	(7)	108,358		108,393
Gateway Portfolio Holdings LLC	Gateway Commons	50.0	%	(8)	332,591		336,206
Rosecrans-Sepulveda Partners 4, LLC	Beach Cities Media Campus	50.0	%		27,162		27,184
					$	1,272,076	$	1,273,919

_______________

(1)Investments with deficit balances aggregating approximately $35.6 million and $36.6 million at March 31, 2021 and December 31, 2020, 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. At March 31, 2021 and December 31, 2020, the Company’s economic ownership was approximately 50%.

(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)On March 30, 2021, the Company sold its interest in the joint venture to the partner. See below for additional details.

(5)The property was sold on June 27, 2019. As of December 31, 2020, the investment consisted of undistributed cash. All remaining cash has been distributed as of March 31, 2021.

(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 2).

(8)As a result of the partner’s deferred contribution, the Company owned an approximately 54% and 55% interest in the joint venture at March 31, 2021 and December 31, 2020, respectively. Future development projects will be owned 49% by the Company and 51% by its partner.

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:


	March 31, 2021		December 31, 2020
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	4,711,593	$	4,708,571
Other assets	505,554		531,071
Total assets	$	5,217,147	$	5,239,642
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	2,662,616	$	2,637,911
Other liabilities (2)	599,354		650,433
Members’/Partners’ equity	1,955,177		1,951,298
Total liabilities and members’/partners’ equity	$	5,217,147	$	5,239,642
Company’s share of equity	$	933,739	$	936,087
Basis differentials (3)	338,337		337,832
Carrying value of the Company’s investments in unconsolidated joint ventures (4)	$	1,272,076	$	1,273,919

_______________

(1)At March 31, 2021 and December 31, 2020, this amount included right of use assets - finance leases totaling approximately $248.9 million and $248.9 million, respectively, and right of use assets - operating leases totaling approximately $22.2 million and $22.5 million, respectively.

(2)At March 31, 2021 and December 31, 2020, this amount included lease liabilities - finance leases totaling approximately $387.9 million and $388.7 million, respectively, and lease liabilities - operating leases totaling approximately $29.2 million and $29.0 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. The Company’s basis differences are as follows:


	March 31, 2021		December 31, 2020
	(in thousands)
Property
Colorado Center	$	306,903	$	307,328
Gateway Commons	50,682		51,875
Dock 72	(51,708)		(52,243)

These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.

(4)Investments with deficit balances aggregating approximately $35.6 million and $36.6 million at March 31, 2021 and December 31, 2020, respectively, are 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:


	Three months ended March 31,
	2021		2020
	(in thousands)
Total revenue (1)	$	87,266	$	93,203
Expenses
Operating	37,134		35,401
Transaction costs	7		—
Depreciation and amortization	34,103		32,035
Total expenses	71,244		67,436
Other income (expense)
Interest expense	(25,556)		(22,583)

Net income (loss)	$	(9,534)	$	3,184

Company’s share of net income (loss)	$	(3,640)	$	1,252
Gain on sale of investment (2)	10,257		—
Basis differential (3)	(1,392)		(1,621)
Income (loss) from unconsolidated joint ventures	$	5,225	$	(369)

_______________

(1)Includes straight-line rent adjustments of approximately $1.1 million and $9.7 million for the three months ended March 31, 2021 and 2020, respectively. For the three months ended March 31, 2021, write-offs of accounts receivable and accrued rent balances totaled approximately $0.3 million.

(2)During the three months ended March 31, 2021, the Company completed the sale of its 50% ownership interest in Annapolis Junction NFM LLC. The Company recognized a gain on sale of investment of approximately $10.3 million.

(3)Includes straight-line rent adjustments of approximately $0.5 million and $0.5 million for the three months ended March 31, 2021 and 2020, respectively. Also includes net above-/below-market rent adjustments of approximately $0.1 million and $0.3 million for the three months ended March 31, 2021 and 2020, respectively.

On February 25, 2021, a joint venture in which the Company has a 54% interest, commenced the development of 751 Gateway, a speculative laboratory building located in South San Francisco, California, that is expected to be approximately 229,000 net rentable square feet upon completion. 751 Gateway is the first phase of a multi-phase development plan at Gateway Commons. Upon the formation of the joint venture in 2020, the Company had an approximately 55% ownership interest in the joint venture as a result of the partner’s deferred contribution and the partner is obligated to fund all required capital until such time as the Company owns a 50% interest. On March 31, 2021, the Company had a 54% interest in the joint venture. The Company will own a 49% interest in any development project, including 751 Gateway.

On March 30, 2021, the Company completed the sale of its 50% ownership interest in Annapolis Junction NFM LLC (the “Annapolis Junction Joint Venture”) to the joint venture partner for a gross sales price of $65.9 million. Net cash proceeds to the Company totaled approximately $17.6 million after repayment of the Company's share of debt totaling approximately $15.1 million and the deferment of a $0.2 million payment due from the purchaser. The Company recognized a gain on sale of investment totaling approximately $10.3 million, which is included in Income (Loss) from Unconsolidated Joint Ventures in the accompanying Consolidated Statements of Operations. In addition to net cash proceeds from the sale, the Company will be distributed approximately $5.8 million of available cash subsequent to March 31, 2021. Annapolis Junction Buildings Six and Seven are Class A office properties totaling approximately 247,000 net rentable square feet. With the sale of the Company’s ownership interest in the Annapolis Junction Joint Venture, the Company no longer has any assets in Annapolis, Maryland.

Mortgage Notes Payable, Net	3 Months Ended
Mortgage Notes Payable, Net	Mar. 31, 2021
Debt Disclosure [Abstract]
Mortgage Notes Payable Disclosure	6. Mortgage Notes PayableOn March 26, 2021, the Company used available cash to repay the mortgage loan collateralized by its University Place property located in Cambridge, Massachusetts totaling approximately $0.9 million. The mortgage loan bore interest at a fixed rate of 6.94% per annum and was scheduled to mature on August 1, 2021. There was no prepayment penalty.

Unsecured Senior Notes

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Unsecured Senior Notes

7. Unsecured Senior Notes

The following summarizes the unsecured senior notes outstanding as of March 31, 2021 (dollars in thousands):


	Coupon/ Stated Rate		Effective Rate(1)		Principal Amount		Maturity Date(2)
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
10.75 Year Unsecured Senior Notes	3.250	%	3.343	%	1,250,000		January 30, 2031
11 Year Unsecured Senior Notes	2.550	%	2.671	%	850,000		April 1, 2032
Total principal					9,700,000
Less:
Net unamortized discount					18,736
Deferred financing costs, net					49,672
Total					$	9,631,592

_______________

(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 February 14, 2021, Boston Properties Limited Partnership completed the redemption of $850.0 million in aggregate principal amount of its 4.125% senior notes due May 15, 2021. The redemption price was approximately $858.7 million, which was equal to par plus approximately $8.7 million of accrued and unpaid interest to, but not including, the redemption date. Excluding the accrued and unpaid interest, the redemption price was equal to the principal amount being redeemed. The Company recognized a loss from early extinguishment of debt totaling approximately $0.4 million related to unamortized origination costs.

On March 16, 2021, Boston Properties Limited Partnership completed a public offering of $850.0 million in aggregate principal amount of its 2.550% unsecured senior notes due 2032. The notes were priced at 99.570% of the principal amount to yield an effective rate (including financing fees) of approximately 2.671% per annum to maturity. The notes will mature on April 1, 2032, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $839.2 million after deducting underwriting discounts and transaction expenses.

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 March 31, 2021, Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.

Unsecured Credit Facility	3 Months Ended
Unsecured Credit Facility	Mar. 31, 2021
Line of Credit Facility [Abstract]
Unsecured line of Credit	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. Prior to its repayment on March 16, 2021, the Delayed Draw Facility bore interest at a variable rate equal to LIBOR plus 0.95% per annum based on Boston Properties Limited Partnership’s credit rating. On March 16, 2021, Boston Properties Limited Partnership repaid all amounts borrowed under the Delayed Draw Facility. The Company recognized a loss from early extinguishment of debt totaling approximately $0.5 million, related to unamortized financing costs. At March 31, 2021, Boston Properties Limited Partnership had no amounts outstanding under its 2017 Credit 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 March 31, 2021, Boston Properties Limited Partnership was in compliance with each of these financial and other covenant requirements.

Commitments And Contingencies	3 Months Ended
Commitments And Contingencies	Mar. 31, 2021
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 $20.2 million at March 31, 2021. 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. 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 March 31, 2021, the maximum funding obligation under the guarantee was approximately $23.1 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 March 31, 2021, 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 provided a financing guaranty as required with respect to the 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 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. An affiliate of The Bernstein Companies exercised its option to borrow $10.0 million from the Company under such agreements, which financing was provided by the Company on June 1, 2020. The financing bears interest at a fixed rate of 8.00% per annum, compounded monthly, and matures on the fifth anniversary of the date on which the base building of the affiliate of The Bernstein Companies’ hotel property is substantially completed. The financing is collateralized by a pledge of the partner’s equity interest in the joint venture that owns and is developing 7750 Wisconsin Avenue. 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 March 31, 2021, 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 March 31, 2021, no amounts related to the contingent aspect of the guarantee are recorded as a liability in the Company’s consolidated financial statements. In connection with the redevelopment of the Company’s 325 Main Street property located in Cambridge, Massachusetts, the Company was required, pursuant to the local zoning ordinance and urban renewal plan, 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, which is expected to occur during the third quarter of 2022. The zoning ordinance and urban renewal plan were each recently amended to decouple the residential requirement from the occupancy of the 325 Main Street property. The amendment to the urban renewal plan is subject to final approvals and completion of administrative processes. 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. 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.” The program trigger is $200 million, the coinsurance is 20% and the deductible is 20% of the premiums earned by the insurer for the year prior to a claim. 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. Due to the current COVID-19 pandemic, the Company anticipates the possibility of business interruption, loss of lease revenue and/or other associated expenses related to the Company’s operations across its portfolio. Because this is an ongoing situation it is not yet possible to quantify the Company’s losses and expenses, which continue to develop. Because of the complexity of the Company’s insurance policies and limited precedent for claims being made related to pandemics, it is not yet possible to determine if such losses and expenses will be covered by the Company’s insurance policies. Therefore, at this time, the Company is providing notice to the applicable insurers of the potential for claims in order to protect the Company’s rights under its policies. The Company continues to monitor the state of the insurance market in general, and the scope and costs of coverage for acts of terrorism, California earthquake risk and pandemics, 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, pandemics 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.

Noncontrolling Interests

3 Months Ended

Mar. 31, 2021

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 March 31, 2021, the noncontrolling interests in Boston Properties Limited Partnership consisted of 16,053,640 OP Units, 1,525,306 LTIP Units (including 451,043 LTIP Units earned by employees under the Company’s multi-year long-term incentive awards granted between 2012-2018 (i.e., 2012 OPP and 2013-2018 MYLTIP awards)), 219,916 2019 MYLTIP Units, 203,278 2020 MYLTIP Units and 352,021 2021 MYLTIP Units held by parties other than Boston Properties, Inc.

Noncontrolling Interest—Common Units

During the three months ended March 31, 2021, 118,290 OP Units were presented by the holders for redemption (including 64,799 OP Units issued upon conversion of LTIP Units, 2012 OPP Units and MYLTIP Units) and were redeemed by Boston Properties, Inc. in exchange for an equal number of shares of Common Stock.

At March 31, 2021, Boston Properties Limited Partnership had outstanding 219,916 2019 MYLTIP Units, 203,278 2020 MYLTIP Units and 352,021 2021 MYLTIP Units. Prior to the end of the respective three-year performance period for each plan, holders of MYLTIP Units are 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 5, 2021, the measurement period for the Company’s 2018 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 29.2% of target, or an aggregate of approximately $4.6 million (after giving effect to employee separations). As a result, an aggregate of 285,925 2018 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 - 2017 MYLTIP Units and, after the February 5, 2021 measurement date, the 2018 MYLTIP Units) and its distributions on the 2018 MYLTIP Units (prior to the February 5, 2021 measurement date) and 2019 - 2021 MYLTIP Units (after the February 2, 2021 issuance date of the 2021 MYLTIP Units) that occurred during the three months ended March 31, 2021:

Record Date

Payment Date

Distributions per OP Unit and LTIP Unit

Distributions per MYLTIP Unit

March 31, 2021

April 30, 2021

$0.98

$0.098

December 31, 2020

January 28, 2021

$0.98

$0.098

The following table presents Boston Properties Limited Partnership’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units, 2013 - 2016 MYLTIP Units and, after the February 6, 2020 measurement date, the 2017 MYLTIP Units) and its distributions on the 2017 MYLTIP Units (prior to the February 6, 2020 measurement date) and 2018 - 2020 MYLTIP Units (after the February 4, 2020 issuance date of the 2020 MYLTIP Units) that occurred during the three months ended March 31, 2020:

Record Date

Payment Date

Distributions per OP Unit and LTIP Unit

Distributions per MYLTIP Unit

March 31, 2020

April 30, 2020

$0.98

$0.098

December 31, 2019

January 30, 2020

$0.98

$0.098

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 and 2013 - 2018 MYLTIP Units) assuming that all conditions had been met for the conversion thereof) had all of such

units been redeemed at March 31, 2021 was approximately $1.8 billion based on the last reported price of a share of Common Stock on the New York Stock Exchange of $101.26 per share on March 31, 2021.

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 March 31, 2021 and December 31, 2020, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.

Stockholders' Equity / Partners' Capital

3 Months Ended

Mar. 31, 2021

Equity [Abstract]

Stockholders' Equity / Partners' Capital

11. Stockholders’ Equity / Partners’ Capital

Boston Properties, Inc.

As of March 31, 2021, Boston Properties, Inc. had 156,074,200 shares of Common Stock outstanding.

As of March 31, 2021, Boston Properties, Inc. owned 1,736,531 general partnership units and 154,337,669 limited partnership units in Boston Properties Limited Partnership.

On May 22, 2020, 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. Under the ATM stock offering program, Boston Properties, Inc. may also engage in forward sale transactions with affiliates of certain sales agents for the sale of its Common Stock on a forward basis. This program replaced Boston Properties, Inc.’s prior $600.0 million ATM stock offering program that was scheduled to expire on June 2, 2020. Boston Properties, Inc. 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 three months ended March 31, 2021, Boston Properties, Inc. issued 206,377 shares of Common Stock upon the exercise of options to purchase Common Stock.

During the three months ended March 31, 2021, Boston Properties, Inc. issued 118,290 shares of Common Stock 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 declared in 2021 and during the three months ended March 31, 2020:


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)



March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98




March 31, 2020	April 30, 2020	$0.98	$0.98
December 31, 2019	January 30, 2020	$0.98	$0.98

Preferred Stock

On March 2, 2021, Boston Properties, Inc. issued a redemption notice for 80,000 shares of its Series B Preferred Stock, which constituted all of the outstanding Series B Preferred Stock, and the corresponding Depositary Shares, each representing 1/100th of a share of Series B Preferred Stock, and recorded it as a liability. The redemption price per share of Series B Preferred Stock was equal to $2,500 plus all accrued and unpaid dividend to, but not including, the redemption date, totaling $2,516.41 per share. On March 31, 2021, the Company transferred the full redemption price for all outstanding shares of Series B Preferred Stock of approximately $201.3 million including approximately $1.3 million of accrued and unpaid dividends to, but not including, the redemption date, to the redemption agent and recorded that amount within Cash held in escrows on the Consolidated Balance Sheets. Upon redemption of the Series B Preferred Stock, all outstanding shares of the Series B Preferred Units, which had terms and preferences generally mirroring those of the Series B Preferred Stock, were redeemed by Boston Properties Limited Partnership. The excess of the redemption price over the

carrying value of the Series B Preferred Stock and Series B Preferred Units of approximately $6.4 million relates to the original issuance costs and will be reflected as a reduction to Net Income Attributable to Boston Properties, Inc. common shareholders and Net Income Attributable to Boston Properties Limited Partnership common unitholders on the Consolidated Income Statement (See Note 15).

The following table presents Boston Properties, Inc.’s dividends per share on its outstanding Series B Preferred Stock paid or declared during 2021 and during the three months ended March 31, 2020:

Record Date

Payment Date

Dividend (Per Share)

February 5, 2021

February 16, 2021

$32.8125

May 1, 2020

May 15, 2020

$32.8125

February 4, 2020

February 18, 2020

$32.8125

Segment Information

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

12. 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 three months ended March 31, 2021 and 2020.

Boston Properties, Inc.


	Three months ended March 31,
	2021		2020
	(in thousands)
Net income attributable to Boston Properties, Inc. common shareholders	$	91,624	$	497,496
Add:
Preferred stock redemption charge	6,412		—
Preferred dividends	2,560		2,625
Noncontrolling interest—common units of the Operating Partnership	11,084		57,539
Noncontrolling interests in property partnerships	16,467		19,486
Interest expense	107,902		101,591
Losses from early extinguishment of debt	898		—

Net operating income from unconsolidated joint ventures	24,795		28,758
Depreciation and amortization expense	176,565		171,094
Transaction costs	331		615
Payroll and related costs from management services contracts	3,505		3,237
General and administrative expense	44,959		36,454
Less:
Net operating income attributable to noncontrolling interests in property partnerships	44,376		47,661
Gains (losses) from investments in securities	1,659		(5,445)
Interest and other income (loss)	1,168		3,017
Gains on sales of real estate	—		410,165
Income (loss) from unconsolidated joint ventures	5,225		(369)
Direct reimbursements of payroll and related costs from management services contracts	3,505		3,237
Development and management services revenue	6,803		7,879
Company’s share of Net Operating Income	$	424,366	$	452,750

Boston Properties Limited Partnership


	Three months ended March 31,
	2021		2020
	(in thousands)
Net income attributable to Boston Properties Limited Partnership common unitholders	$	105,773	$	566,333
Add:
Preferred unit redemption charge	6,412		—
Preferred distributions	2,560		2,625
Noncontrolling interests in property partnerships	16,467		19,486
Interest expense	107,902		101,591
Losses from early extinguishment of debt	898		—

Net operating income from unconsolidated joint ventures	24,795		28,758
Depreciation and amortization expense	173,500		169,285
Transaction costs	331		615
Payroll and related costs from management services contracts	3,505		3,237
General and administrative expense	44,959		36,454
Less:
Net operating income attributable to noncontrolling interests in property partnerships	44,376		47,661
Gains (losses) from investments in securities	1,659		(5,445)
Interest and other income (loss)	1,168		3,017
Gains on sales of real estate	—		419,654
Income (loss) from unconsolidated joint ventures	5,225		(369)
Direct reimbursements of payroll and related costs from management services contracts	3,505		3,237
Development and management services revenue	6,803		7,879
Company’s share of Net Operating Income	$	424,366	$	452,750

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 stock/unit redemption charge, preferred dividends/distributions, net income attributable to noncontrolling interests, interest expense, losses from early extinguishment of debt, 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 (loss), gains on sales of real estate, income (loss) 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.

The Company’s internal reporting utilizes its share of NOI, which includes its share of NOI from consolidated and unconsolidated joint ventures, which is a non-GAAP financial measure that is calculated as the consolidated amount, plus the Company’s share of the amount from the Company’s unconsolidated joint ventures (calculated based upon the Company’s economic percentage ownership interest and, in some cases, after priority allocations), minus the Company’s partners’ share of the amount from the Company’s consolidated joint ventures (calculated based upon the partners’ economic percentage ownership interests and, in some cases, after priority allocations, income allocation to private REIT shareholders and their share of fees due to the Company). The Company’s share of NOI from unconsolidated joint ventures does not include its share of gains on sales of real estate from unconsolidated joint ventures, both of which are included within Income From Unconsolidated Joint Ventures in the Company’s Consolidated Statements of Operations. Management utilizes its share of NOI in assessing its performance as the Company has several significant joint ventures and, in some cases, the Company exercises significant influence over, but does not control, the joint venture, in which case GAAP requires that the Company account for the joint venture entity using the equity method of accounting and the Company does not consolidate it for financial reporting purposes. In other cases, GAAP requires that the Company consolidate the venture even though the Company’s partner(s) owns a significant percentage interest. As a result, the presentations of the Company’s share of NOI should not be considered a substitute for, and should only be considered together with and as a supplement to, the Company’s financial information presented in accordance with GAAP.

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 stock/unit redemption charge, preferred dividends/distributions, interest expense, losses from early extinguishment of debt, 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 (loss), gains on sales of real estate, income (loss) from unconsolidated joint ventures, 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.

Included within the Office property type are commercial office and retail leases, as well as parking revenue. Upon the adoption of ASC 842, any write-off for bad debt, including accrued rent, will be recorded as a reduction to lease revenue. As a result of COVID-19, during the three months ended March 31, 2021, the Company wrote off approximately $0.6 million related to accrued rent, net balances and approximately $(0.2) million related to accounts receivable, net balances. During the three months ended March 31, 2020, the Company wrote off approximately $1.2 million related to accrued rent, net balances and approximately $0.3 million related to accounts receivable, net balances. The write-offs were for tenants, primarily in the retail sector, that either terminated their leases or that the Company considered their accrued rent and/or accounts receivable balances no longer probable of collection.

In addition, parking and other revenue for the three months ended March 31, 2021 decreased by approximately $7.6 million compared to 2020. These decreases were primarily in transient and monthly parking revenue.

The Boston Marriott Cambridge closed in March 2020 due to COVID-19. The hotel re-opened on October 2, 2020 and it has operated at a diminished occupancy due to the continued impact of COVID-19 on business and leisure travel. The closing of the hotel for more than two fiscal quarters, weak demand and low occupancy since its re-opening, have had, and are expected to continue to have, a material adverse effect on the hotel’s operations and thus the results of the Company’s Hotel property type.

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

For the three months ended March 31, 2021:


	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	230,403		$	—		$	250,164		$	130,598		$	82,415		$	693,580
Residential	3,045			—			—			321			5,809			9,175
Hotel	632			—			—			—			—			632
Total	234,080			—			250,164			130,919			88,224			703,387
% of Grand Totals	33.28		%	—		%	35.57		%	18.61		%	12.54		%	100.00		%
Rental Expenses:
Office	79,881			—			99,385			40,249			31,747			251,262
Residential	1,455			—			—			1,686			2,986			6,127
Hotel	2,051			—			—			—			—			2,051
Total	83,387			—			99,385			41,935			34,733			259,440
% of Grand Totals	32.14		%	—		%	38.31		%	16.16		%	13.39		%	100.00		%
Net operating income	$	150,693		$	—		$	150,779		$	88,984		$	53,491		$	443,947
% of Grand Totals	33.94		%	—		%	33.97		%	20.04		%	12.05		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(10,224)			—			(34,152)			—			—			(44,376)
Add: Company’s share of net operating income from unconsolidated joint ventures	2,281			14,192			(793)			3,480			5,635			24,795
Company’s share of net operating income	$	142,750		$	14,192		$	115,834		$	92,464		$	59,126		$	424,366
% of Grand Totals	33.64		%	3.34		%	27.30		%	21.79		%	13.93		%	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 three months ended March 31, 2020:


	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	239,498		$	—		$	255,286		$	136,739		$	93,136		$	724,659
Residential	4,068			—			—			—			5,888			9,956
Hotel	6,825			—			—			—			—			6,825
Total	250,391			—			255,286			136,739			99,024			741,440
% of Grand Totals	33.77		%	—		%	34.43		%	18.44		%	13.36		%	100.00		%
Rental Expenses:
Office	82,545			—			99,140			42,569			34,648			258,902
Residential	1,340			—			—			—			2,724			4,064
Hotel	6,821			—			—			—			—			6,821
Total	90,706			—			99,140			42,569			37,372			269,787
% of Grand Totals	33.62		%	—		%	36.75		%	15.78		%	13.85		%	100.00		%
Net operating income	$	159,685		$	—		$	156,146		$	94,170		$	61,652		$	471,653
% of Grand Totals	33.85		%	—		%	33.11		%	19.97		%	13.07		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(10,663)			—			(36,998)			—			—			(47,661)
Add: Company’s share of net operating income from unconsolidated joint ventures	3,099			15,930			756			3,159			5,814			28,758
Company’s share of net operating income	$	152,121		$	15,930		$	119,904		$	97,329		$	67,466		$	452,750
% of Grand Totals	33.60		%	3.52		%	26.48		%	21.50		%	14.90		%	100.00		%

_______________

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 31
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8924-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8981-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 21
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Topic 280
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8933-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8721-108599

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Earnings Per Share / Common Unit

3 Months Ended

Mar. 31, 2021

Earnings Per Share [Abstract]

Earnings Per Share / Common Unit

13. 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 and 2013 - 2018 MYLTIP Units required, and the 2019 - 2021 MYLTIP Units require, Boston Properties, Inc. to outperform absolute and/or 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.


	Three months ended March 31, 2021
	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	$	91,624	155,928	$	0.59
Effect of Dilutive Securities:
Stock Based Compensation	—		171	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	91,624	156,099	$	0.59

	Three months ended March 31, 2020
	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	$	497,496	155,011	$	3.21
Allocation of undistributed earnings to participating securities	(1,011)		—	(0.01)
Net income attributable to Boston Properties, Inc. common shareholders	$	496,485	155,011	$	3.20
Effect of Dilutive Securities:
Stock Based Compensation	—		247	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,485	155,258	$	3.20

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 and 2013 - 2018 MYLTIP Units required, and the 2019 - 2021 MYLTIP Units require, Boston Properties, Inc. to outperform absolute and/or 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 17,089,000 and 17,538,000 redeemable common units for the three months ended March 31, 2021, and 2020, respectively.


	Three months ended March 31, 2021
	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	$	105,773	173,018	$	0.61
Effect of Dilutive Securities:
Stock Based Compensation	—		171	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	105,773	173,189	$	0.61

	Three months ended March 31, 2020
	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	$	566,333	172,549	$	3.28
Allocation of undistributed earnings to participating securities	(1,126)		—	—
Net income attributable to Boston Properties Limited Partnership common unitholders	$	565,207	172,549	$	3.28
Effect of Dilutive Securities:
Stock Based Compensation	—		247	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	565,207	172,796	$	3.27

Stock Option and Incentive Plan	3 Months Ended
Stock Option and Incentive Plan	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock Option and Incentive Plan	14. Stock Option and Incentive Plan On February 2, 2021, Boston Properties, Inc.’s Compensation Committee approved the 2021 MYLTIP awards under the Boston Properties, Inc. 2012 Stock Option and Incentive Plan (the “2012 Plan”) to certain officers and employees of Boston Properties, Inc. The 2021 MYLTIP awards consist of two, equally-weighted (50% each) components that utilize Boston Properties, Inc.’s TSR over a three-year measurement period as the performance metric. The first component of the 2021 MYLTIP, which represents one-half (50%) of the target grant-date value, retains the basic general structure of the 2020 MYLTIP awards with certain changes, including a change to the custom index against which Boston Properties, Inc.’s TSR is compared. The number of LTIP Units that can be earned under this component ranges from zero to 200% of the target number of LTIP Units, based on Boston Properties, Inc.’s annualized relative TSR performance compared to a custom index. Under this component, 100% of the target number of LTIP Units will be earned if Boston Properties, Inc.’s TSR equals the custom index TSR; for relative TSR performance between -1,000 basis points and +1,000 basis points, the number of LTIP Units earned will be determined using linear interpolation. The second component represents the remaining one-half (50%) of the target grant-date value of the 2021 MYLTIP. The number of LTIP Units that can be earned under this component ranges from zero to 200% of the target number of LTIP Units, based on Boston Properties, Inc.’s cumulative absolute TSR during the performance period. Under this component, 100% of the target number of LTIP Units will be earned if Boston Properties, Inc.’s achieves an absolute TSR equal to +1,000 basis points; if Boston Properties, Inc.’s absolute TSR is greater than -4,000 basis points but less than +6,000 basis points, then the number of LTIP Units earned will be determined using linear interpolation. Total earned awards under the 2021 MYLTIP, if any, is the sum of the number of LTIP Units earned under the first and second components and will range from zero to a maximum of 352,021 LTIP Units with a target of approximately 176,009 LTIP Units and linear interpolation between zero and maximum. Earned awards (if any) will vest 100% on February 1, 2024, but may not be converted, redeemed, sold or otherwise transferred for one additional year thereafter. 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 1, 2024, earned awards will be calculated based on TSR performance up to the date of the change of control. The 2021 MYLTIP awards are in the form of LTIP Units issued on the grant date, and they are subject to forfeiture to the extent awards are not earned. Prior to the performance measurement date holders of the 2021 MYLTIP Units are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units. Following the completion of the three-year performance period, Boston Properties, Inc. will also make a “catch-up” cash payment on the 2021 MYLTIP Units that are ultimately earned in an amount equal to the regular and special distributions, if any, declared during the performance period on Boston Properties, Inc.’s common stock, less the distributions actually paid to holders of 2021 MYLTIP Units during the performance period on all of the awarded 2021 MYLTIP Units. Under ASC 718 “Compensation - Stock Compensation,” the 2021 MYLTIP awards have an aggregate value of approximately $15.3 million, which amount will generally be amortized into earnings under the graded vesting method. On February 5, 2021, the measurement period for the Company’s 2018 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 29.2% of target, or an aggregate of approximately $4.6 million (after giving effect to employee separations). As a result, an aggregate of 285,925 2018 MYLTIP Units that had been previously granted were automatically forfeited. During the three months ended March 31, 2021, Boston Properties, Inc. issued 34,644 shares of restricted common stock and Boston Properties Limited Partnership issued 273,930 LTIP Units and 352,021 2021 MYLTIP Units to employees under the 2012 Plan. Employees paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit and 2021 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 of Boston Properties, Inc. and Boston Properties Limited Partnership. A substantial majority of the grants of restricted common stock and LTIP Units to employees vest in four equal annual installments. Restricted common 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. The shares of restricted common stock granted during the three months ended March 31, 2021 were valued at approximately $3.2 million ($91.67 per share weighted-average). The LTIP Units granted were valued at approximately $23.0 million (approximately $83.85 per unit weighted-average fair value) using a Monte Carlo simulation method model. The per unit fair values of the LTIP Units granted were estimated on the dates of grant and for a substantial majority of such units were valued using the following assumptions: an expected life of 5.7 years, a risk-free interest rate of 0.65% and an expected price volatility of 30.0%. Because the 2012 OPP Units and 2013 - 2021 MYLTIP Units are subject to both a service condition and a market condition, the Company recognizes the related compensation expense 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, LTIP Units and 2016 - 2021 MYLTIP Units was approximately $19.8 million and $17.2 million for the three months ended March 31, 2021 and 2020, respectively. At March 31, 2021, there was (1) an aggregate of approximately $33.4 million of unrecognized compensation expense related to unvested restricted stock, LTIP Units and 2018 MYLTIP Units and (2) an aggregate of approximately $19.2 million of unrecognized compensation expense related to unvested 2019 - 2021 MYLTIP Units that is expected to be recognized over a weighted-average period of approximately 2.4 years.

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	15. Subsequent Events On April 1, 2021, Boston Properties, Inc. redeemed 80,000 shares of Series B Preferred Stock (including the corresponding 8,000,000 Depositary Shares), which represented all of the outstanding shares of Series B Preferred Stock. Upon redemption of the Series B Preferred Stock, all outstanding shares of the Series B Preferred Units, which had terms and preferences generally mirroring those of the Series B Preferred Stock, were redeemed by Boston Properties Limited Partnership. The Company paid an aggregate $201.3 million including $1.3 million of accrued but unpaid interest (See Note 11). On May 3, 2021, the Company entered into an agreement to acquire two life sciences lab buildings located in Waltham, Massachusetts for a purchase price of approximately $100.0 million. These two life sciences lab buildings aggregate approximately 137,000 net rentable square feet. The properties are 100% leased. The Company expects to close on the acquisition during the second quarter of 2021. The transaction is subject to the satisfaction of customary closing conditions. There can be no assurance that the acquisition will be consummated on the terms currently contemplated, or at all.

Organization (Policies)	3 Months Ended
Organization (Policies)	Mar. 31, 2021
Text Block [Abstract]
Basis of Presentation	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.The accompanying interim financial statements are unaudited; however, the financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission. Accordingly, they do not include all of the disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting solely of normal recurring matters) necessary for a fair statement of the financial statements for these interim periods have been included. The results of operations for the interim periods are not necessarily indicative of the results to be obtained for other interim periods or for the full fiscal year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosure required by GAAP. These financial statements should be read in conjunction with the Company’s financial statements and notes thereto contained in the Company’s Annual Report in the Company’s Form 10-K for its fiscal year ended December 31, 2020.

Summary Of Significant Accounting Policies (Policies)	3 Months Ended
Summary Of Significant Accounting Policies (Policies)	Mar. 31, 2021
Accounting Policies [Abstract]
Consolidation, Variable Interest Entity, Policy	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.
Use of Estimates in the Preparation of Financial Statements	The Company bases its estimates on historical experience and on various other assumptions that it considers to be reasonable under the circumstances, including the impact of extraordinary events such as the novel coronavirus (“COVID-19”) pandemic, the results of which form the basis for making significant judgments about the carrying values of assets and liabilities, assessments of future collectability, and other areas of the financial statements that are impacted by the use of estimates. Actual results may differ from these estimates under different assumptions or conditions.

Summary Of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2021

Summary Of Significant Accounting Policies [Line Items]

Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]


Financial Instrument			Level
Unsecured senior notes (1)			Level 1
Related party note receivable			Level 3
Notes receivable			Level 3
Mortgage notes payable			Level 3
Unsecured line of credit (2)			Level 3

_______________

(1)If trading value for the period is low, the valuation could be categorized as Level 2.

(2)As of March 31, 2021, there were no amounts outstanding under the unsecured line of credit.

The following table identifies the range and weighted average of significant unobservable inputs for the Company’s Level 3 fair value measured instruments.


Financial Instrument	Level	Range	Weighted Average
Related party note receivable	Level 3	3.61%	3.61%
Notes receivable	Level 3	3.60% - 8.00%	5.85%
Mortgage notes payable	Level 3	2.75% - 3.07%	2.82%

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


	March 31, 2021				December 31, 2020
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable, net	$	77,640	$	84,205	$	77,552	$	84,579
Notes receivable, net	18,891		19,541		18,729		19,372
Total	$	96,531	$	103,746	$	96,281	$	103,951

Mortgage notes payable, net	$	2,904,672	$	3,025,986	$	2,909,081	$	3,144,150
Unsecured senior notes, net	9,631,592		10,216,659		9,639,287		10,620,527
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	—		—		499,390		500,326
Total	$	12,536,264	$	13,242,645	$	13,047,758	$	14,265,003

Real Estate (Tables)

3 Months Ended

Mar. 31, 2021

Schedule of Real Estate Properties

Boston Properties, Inc.

Real estate consisted of the following at March 31, 2021 and December 31, 2020 (in thousands):


	March 31, 2021		December 31, 2020
Land	$	5,068,843	$	5,069,206
Right of use assets - finance leases	237,017		237,393
Right of use assets - operating leases	144,143		146,406
Land held for future development (1)	421,349		450,954
Buildings and improvements	14,004,418		13,777,691
Tenant improvements	2,816,726		2,752,880
Furniture, fixtures and equipment	51,549		49,606
Construction in progress	794,039		868,773
Total	23,538,084		23,352,909
Less: Accumulated depreciation	(5,665,061)		(5,534,102)
	$	17,873,023	$	17,818,807

_______________

(1)Includes pre-development costs.

Schedule of Real Estate Properties

Boston Properties Limited Partnership

Real estate consisted of the following at March 31, 2021 and December 31, 2020 (in thousands):


	March 31, 2021		December 31, 2020
Land	$	4,971,990	$	4,971,990
Right of use assets - finance leases	237,017		237,393
Right of use assets - operating leases	144,143		146,406
Land held for future development (1)	421,349		450,954
Buildings and improvements	13,725,776		13,498,098
Tenant improvements	2,816,726		2,752,880
Furniture, fixtures and equipment	51,549		49,606
Construction in progress	794,039		868,773
Total	23,162,589		22,976,100
Less: Accumulated depreciation	(5,557,784)		(5,428,576)
	$	17,604,805	$	17,547,524

_______________

(1)Includes pre-development costs.

Leases (Tables)

3 Months Ended

Mar. 31, 2021

Leases [Abstract]

Operating Lease, Lease Income [Table Text Block]


	Three months ended March 31,
Lease Revenue	2021		2020
Fixed contractual payments	$	575,353	$	586,957
Variable lease payments	110,464		123,154
	$	685,817	$	710,111

Investments in Unconsolidated Joint Ventures (Tables)

3 Months Ended

Mar. 31, 2021

Schedule of Equity Method Investments [Line Items]

Investments In Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at March 31, 2021 and December 31, 2020:


					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			March 31, 2021		December 31, 2020
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.0	%		$	(3,293)	$	(3,766)
BP/CRF Metropolitan Square LLC	Metropolitan Square	20.0	%		(12,971)		(13,584)
901 New York, LLC	901 New York Avenue	25.0	%	(2)	(12,198)		(12,264)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.3	%	(3)	34,887		35,297
Annapolis Junction NFM LLC	Annapolis Junction	50.0	%	(4)	—		13,463
540 Madison Venture LLC	540 Madison Avenue	60.0	%	(5)	—		122
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.0	%		(7,187)		(6,945)
501 K Street LLC	1001 6th Street	50.0	%	(6)	42,607		42,499
Podium Developer LLC	The Hub on Causeway - Podium	50.0	%		48,398		48,818
Residential Tower Developer LLC	Hub50House	50.0	%		49,520		50,943
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.0	%		11,032		10,754
Office Tower Developer LLC	100 Causeway Street	50.0	%		56,458		56,312
1265 Main Office JV LLC	1265 Main Street	50.0	%		3,899		3,787
BNY Tower Holdings LLC	Dock 72	50.0	%		27,936		29,536
BNYTA Amenity Operator LLC	Dock 72	50.0	%		1,672		1,846
CA-Colorado Center Limited Partnership	Colorado Center	50.0	%		229,094		227,671
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.0	%		58,697		58,112
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.0	%		115,869		113,774
SMBP Venture LP	Santa Monica Business Park	55.0	%		159,545		145,761
Platform 16 Holdings LP	Platform 16	55.0	%	(7)	108,358		108,393
Gateway Portfolio Holdings LLC	Gateway Commons	50.0	%	(8)	332,591		336,206
Rosecrans-Sepulveda Partners 4, LLC	Beach Cities Media Campus	50.0	%		27,162		27,184
					$	1,272,076	$	1,273,919

_______________

(4)On March 30, 2021, the Company sold its interest in the joint venture to the partner. See below for additional details.

(5)The property was sold on June 27, 2019. As of December 31, 2020, the investment consisted of undistributed cash. All remaining cash has been distributed as of March 31, 2021.

(7)This entity is a VIE (See Note 2).

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:


	March 31, 2021		December 31, 2020
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	4,711,593	$	4,708,571
Other assets	505,554		531,071
Total assets	$	5,217,147	$	5,239,642
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	2,662,616	$	2,637,911
Other liabilities (2)	599,354		650,433
Members’/Partners’ equity	1,955,177		1,951,298
Total liabilities and members’/partners’ equity	$	5,217,147	$	5,239,642
Company’s share of equity	$	933,739	$	936,087
Basis differentials (3)	338,337		337,832
Carrying value of the Company’s investments in unconsolidated joint ventures (4)	$	1,272,076	$	1,273,919

_______________


	March 31, 2021		December 31, 2020
	(in thousands)
Property
Colorado Center	$	306,903	$	307,328
Gateway Commons	50,682		51,875
Dock 72	(51,708)		(52,243)

These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.

Statements Of Operations Of The Joint Ventures

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


	Three months ended March 31,
	2021		2020
	(in thousands)
Total revenue (1)	$	87,266	$	93,203
Expenses
Operating	37,134		35,401
Transaction costs	7		—
Depreciation and amortization	34,103		32,035
Total expenses	71,244		67,436
Other income (expense)
Interest expense	(25,556)		(22,583)

Net income (loss)	$	(9,534)	$	3,184

Company’s share of net income (loss)	$	(3,640)	$	1,252
Gain on sale of investment (2)	10,257		—
Basis differential (3)	(1,392)		(1,621)
Income (loss) from unconsolidated joint ventures	$	5,225	$	(369)

_______________

Unsecured Senior Notes (Tables)

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

The following summarizes the unsecured senior notes outstanding as of March 31, 2021 (dollars in thousands):


	Coupon/ Stated Rate		Effective Rate(1)		Principal Amount		Maturity Date(2)
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
10.75 Year Unsecured Senior Notes	3.250	%	3.343	%	1,250,000		January 30, 2031
11 Year Unsecured Senior Notes	2.550	%	2.671	%	850,000		April 1, 2032
Total principal					9,700,000
Less:
Net unamortized discount					18,736
Deferred financing costs, net					49,672
Total					$	9,631,592

_______________

(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.

- Definition

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 505
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Noncontrolling Interests (Tables)

3 Months Ended

Mar. 31, 2021

Noncontrolling Interest [Line Items]

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


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)



March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98




March 31, 2020	April 30, 2020	$0.98	$0.98
December 31, 2019	January 30, 2020	$0.98	$0.98

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

March 31, 2021

April 30, 2021

$0.98

$0.098

December 31, 2020

January 28, 2021

$0.98

$0.098

Record Date

Payment Date

Distributions per OP Unit and LTIP Unit

Distributions per MYLTIP Unit

March 31, 2020

April 30, 2020

$0.98

$0.098

December 31, 2019

January 30, 2020

$0.98

$0.098

Stockholders' Equity / Partners' Capital (Tables)

3 Months Ended

Mar. 31, 2021

Class of Stock [Line Items]

Dividends Declared [Table Text Block]


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)



March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98




March 31, 2020	April 30, 2020	$0.98	$0.98
December 31, 2019	January 30, 2020	$0.98	$0.98

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 declared during 2021 and during the three months ended March 31, 2020:

Record Date

Payment Date

Dividend (Per Share)

February 5, 2021

February 16, 2021

$32.8125

May 1, 2020

May 15, 2020

$32.8125

February 4, 2020

February 18, 2020

$32.8125

Segment Information (Tables)

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Schedule Of Reconciliation Of Net Operating Income To Net Income

Boston Properties, Inc.


	Three months ended March 31,
	2021		2020
	(in thousands)
Net income attributable to Boston Properties, Inc. common shareholders	$	91,624	$	497,496
Add:
Preferred stock redemption charge	6,412		—
Preferred dividends	2,560		2,625
Noncontrolling interest—common units of the Operating Partnership	11,084		57,539
Noncontrolling interests in property partnerships	16,467		19,486
Interest expense	107,902		101,591
Losses from early extinguishment of debt	898		—

Net operating income from unconsolidated joint ventures	24,795		28,758
Depreciation and amortization expense	176,565		171,094
Transaction costs	331		615
Payroll and related costs from management services contracts	3,505		3,237
General and administrative expense	44,959		36,454
Less:
Net operating income attributable to noncontrolling interests in property partnerships	44,376		47,661
Gains (losses) from investments in securities	1,659		(5,445)
Interest and other income (loss)	1,168		3,017
Gains on sales of real estate	—		410,165
Income (loss) from unconsolidated joint ventures	5,225		(369)
Direct reimbursements of payroll and related costs from management services contracts	3,505		3,237
Development and management services revenue	6,803		7,879
Company’s share of Net Operating Income	$	424,366	$	452,750

Boston Properties Limited Partnership


	Three months ended March 31,
	2021		2020
	(in thousands)
Net income attributable to Boston Properties Limited Partnership common unitholders	$	105,773	$	566,333
Add:
Preferred unit redemption charge	6,412		—
Preferred distributions	2,560		2,625
Noncontrolling interests in property partnerships	16,467		19,486
Interest expense	107,902		101,591
Losses from early extinguishment of debt	898		—

Net operating income from unconsolidated joint ventures	24,795		28,758
Depreciation and amortization expense	173,500		169,285
Transaction costs	331		615
Payroll and related costs from management services contracts	3,505		3,237
General and administrative expense	44,959		36,454
Less:
Net operating income attributable to noncontrolling interests in property partnerships	44,376		47,661
Gains (losses) from investments in securities	1,659		(5,445)
Interest and other income (loss)	1,168		3,017
Gains on sales of real estate	—		419,654
Income (loss) from unconsolidated joint ventures	5,225		(369)
Direct reimbursements of payroll and related costs from management services contracts	3,505		3,237
Development and management services revenue	6,803		7,879
Company’s share of Net Operating Income	$	424,366	$	452,750

Schedule Of Segment Information By Geographic Area And Property Type

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

For the three months ended March 31, 2021:


	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	230,403		$	—		$	250,164		$	130,598		$	82,415		$	693,580
Residential	3,045			—			—			321			5,809			9,175
Hotel	632			—			—			—			—			632
Total	234,080			—			250,164			130,919			88,224			703,387
% of Grand Totals	33.28		%	—		%	35.57		%	18.61		%	12.54		%	100.00		%
Rental Expenses:
Office	79,881			—			99,385			40,249			31,747			251,262
Residential	1,455			—			—			1,686			2,986			6,127
Hotel	2,051			—			—			—			—			2,051
Total	83,387			—			99,385			41,935			34,733			259,440
% of Grand Totals	32.14		%	—		%	38.31		%	16.16		%	13.39		%	100.00		%
Net operating income	$	150,693		$	—		$	150,779		$	88,984		$	53,491		$	443,947
% of Grand Totals	33.94		%	—		%	33.97		%	20.04		%	12.05		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(10,224)			—			(34,152)			—			—			(44,376)
Add: Company’s share of net operating income from unconsolidated joint ventures	2,281			14,192			(793)			3,480			5,635			24,795
Company’s share of net operating income	$	142,750		$	14,192		$	115,834		$	92,464		$	59,126		$	424,366
% of Grand Totals	33.64		%	3.34		%	27.30		%	21.79		%	13.93		%	100.00		%

_______________

For the three months ended March 31, 2020:


	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	239,498		$	—		$	255,286		$	136,739		$	93,136		$	724,659
Residential	4,068			—			—			—			5,888			9,956
Hotel	6,825			—			—			—			—			6,825
Total	250,391			—			255,286			136,739			99,024			741,440
% of Grand Totals	33.77		%	—		%	34.43		%	18.44		%	13.36		%	100.00		%
Rental Expenses:
Office	82,545			—			99,140			42,569			34,648			258,902
Residential	1,340			—			—			—			2,724			4,064
Hotel	6,821			—			—			—			—			6,821
Total	90,706			—			99,140			42,569			37,372			269,787
% of Grand Totals	33.62		%	—		%	36.75		%	15.78		%	13.85		%	100.00		%
Net operating income	$	159,685		$	—		$	156,146		$	94,170		$	61,652		$	471,653
% of Grand Totals	33.85		%	—		%	33.11		%	19.97		%	13.07		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(10,663)			—			(36,998)			—			—			(47,661)
Add: Company’s share of net operating income from unconsolidated joint ventures	3,099			15,930			756			3,159			5,814			28,758
Company’s share of net operating income	$	152,121		$	15,930		$	119,904		$	97,329		$	67,466		$	452,750
% of Grand Totals	33.60		%	3.52		%	26.48		%	21.50		%	14.90		%	100.00		%

_______________

Earnings Per Share / Common Unit (Tables)

3 Months Ended

Mar. 31, 2021

Entity Information [Line Items]

Computation Of Basic And Diluted Earnings Per Share / Unit


	Three months ended March 31, 2021
	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	$	91,624	155,928	$	0.59
Effect of Dilutive Securities:
Stock Based Compensation	—		171	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	91,624	156,099	$	0.59

	Three months ended March 31, 2020
	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	$	497,496	155,011	$	3.21
Allocation of undistributed earnings to participating securities	(1,011)		—	(0.01)
Net income attributable to Boston Properties, Inc. common shareholders	$	496,485	155,011	$	3.20
Effect of Dilutive Securities:
Stock Based Compensation	—		247	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,485	155,258	$	3.20

Computation Of Basic And Diluted Earnings Per Share / Unit

Entity Information [Line Items]

Included in the number of units (the denominator) below are approximately 17,089,000 and 17,538,000 redeemable common units for the three months ended March 31, 2021, and 2020, respectively.


	Three months ended March 31, 2021
	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	$	105,773	173,018	$	0.61
Effect of Dilutive Securities:
Stock Based Compensation	—		171	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	105,773	173,189	$	0.61

	Three months ended March 31, 2020
	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	$	566,333	172,549	$	3.28
Allocation of undistributed earnings to participating securities	(1,126)		—	—
Net income attributable to Boston Properties Limited Partnership common unitholders	$	565,207	172,549	$	3.28
Effect of Dilutive Securities:
Stock Based Compensation	—		247	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	565,207	172,796	$	3.27

Organization (Details) $ in Thousands, ft² in Millions	3 Months Ended	12 Months Ended
Organization (Details) $ in Thousands, ft² in Millions	Mar. 31, 2021 USD ($) ft² Real_Estate_Properties yr shares	Dec. 31, 2020 USD ($) shares	Mar. 02, 2021 shares	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)	89.90%	90.00%
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
Cash held in escrows \| $	$ 251,814	$ 50,587		$ 197,845	$ 46,936
Dividends and distributions payable \| $	$ 171,003	$ 171,082		$ 171,026
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	196
Net Rentable Area (in sf) \| ft²	51.6
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties	9
Net Rentable Area (in sf) \| ft²	4.3
Total Office Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	177
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
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
Cash held in escrows \| $	$ 201,300
Dividends and distributions payable \| $	$ 1,300

Summary Of Significant Accounting Policies (Narrative) (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 18, 2021 $ / shares	Dec. 31, 2020 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Interest capitalized	$ 12,032	$ 14,149
Gains (losses) from investments in securities	1,659	(5,445)
Adoption of ASU 2016-13 and 2018-19	(570,982)			$ (509,653)
Adoption of ASU 2016-13 and 2018-19	$ 620,106			616,596
Number of VIEs - Total	7
Number of VIEs	6
Distributions Payable, Amount Per Unit \| $ / shares			$ 0.98
Boston Properties Limited Partnership
Summary Of Significant Accounting Policies [Line Items]
Interest capitalized	$ 12,032	14,149
Gains (losses) from investments in securities	1,659	$ (5,445)
Adoption of ASU 2016-13 and 2018-19	4,392,624			4,554,639
Adoption of ASU 2016-13 and 2018-19	$ 1,780,044			$ 1,643,024
Distributions Payable, Amount Per Unit \| $ / shares			$ 0.98
Commercial Real Estate Properties [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of VIEs	5

Summary Of Significant Accounting Policies Fair Value of Debt (Level 3) (Details) - Measurement Input, Discount Rate [Member]	Mar. 31, 2021
Mortgage Notes [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.0275
Mortgage Notes [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.0307
Mortgage Notes [Member] \| Weighted Average [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.0282
Related Party Note Receivable [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.0361
Related Party Note Receivable [Member] \| Weighted Average [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.0361
Notes Receivables [Member] \| Minimum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.0360
Notes Receivables [Member] \| Maximum [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.0800
Notes Receivables [Member] \| Weighted Average [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Debt Instrument, Measurement Input	0.0585

Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	$ 77,640	$ 77,552
Notes receivable, net	18,891	18,729
Mortgage notes payable, net	2,904,672	2,909,081
Unsecured senior notes, net	9,631,592	9,639,287
Unsecured line of credit	0	0
Unsecured term loan, net	0	499,390
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	77,640	77,552
Notes receivable, net	18,891	18,729
Total	96,531	96,281
Mortgage notes payable, net	2,904,672	2,909,081
Unsecured senior notes, net	9,631,592	9,639,287
Unsecured line of credit	0	0
Unsecured term loan, net	0	499,390
Total	12,536,264	13,047,758
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	84,205	84,579
Notes receivable, net	19,541	19,372
Total	103,746	103,951
Mortgage notes payable, net	3,025,986	3,144,150
Unsecured senior notes, net	10,216,659	10,620,527
Unsecured line of credit	0	0
Unsecured term loan, net	0	500,326
Total	$ 13,242,645	$ 14,265,003

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

Mar. 31, 2021

Dec. 31, 2020

Land

$ 5,068,843

$ 5,069,206

237,017

237,393

Land held for future development

144,143

146,406

^[1]

421,349

450,954

Buildings and improvements

14,004,418

13,777,691

Tenant improvements

2,816,726

2,752,880

Furniture, Fixtures and Equipment

51,549

49,606

Construction in progress

794,039

868,773

Total

23,538,084

23,352,909

Less: accumulated depreciation

(5,665,061)

(5,534,102)

Total real estate

17,873,023

17,818,807

Land

4,971,990

237,017

237,393

Land held for future development

144,143

146,406

^[1]

421,349

450,954

Buildings and improvements

13,725,776

13,498,098

Tenant improvements

2,816,726

2,752,880

Furniture, Fixtures and Equipment

51,549

49,606

Construction in progress

794,039

868,773

Total

23,162,589

22,976,100

Less: accumulated depreciation

(5,557,784)

(5,428,576)

Total real estate

$ 17,604,805

$ 17,547,524

[1]	Includes pre-development costs.

Real Estate (Narrative) (Details) - ft²	Feb. 25, 2021	Feb. 01, 2021
One Five Nine East 53rd Street
Real Estate Properties [Line Items]
Net Rentable Area (in sf)		220,000
Construction in Progress \| 180 CityPoint
Real Estate Properties [Line Items]
Net Rentable Area (in sf)	329,000
Construction in Progress \| 880 Winter Street [Member]
Real Estate Properties [Line Items]
Net Rentable Area (in sf)	224,000
Construction in Progress \| The Prudential Center Observatory
Real Estate Properties [Line Items]
Net Rentable Area (in sf)	59,000

Leases (Details) - USD ($) $ in Thousands	3 Months Ended
Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Fixed contractual payments	$ 575,353	$ 586,957
Variable lease payments	110,464	123,154
Lease	$ 685,817	$ 710,111

Leases Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
Leases Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Mar. 31, 2020
Lessor, Lease, Description [Line Items]
Write-off for accounts receivable		$ 300
Write-off for accrued rent	$ 600	$ 1,200
Write off of accounts receivable	$ (200)

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

3 Months Ended

Mar. 31, 2021

USD ($)

ft²

payments

Mar. 30, 2021

Feb. 25, 2021

Dec. 31, 2020

USD ($)

Schedule of Equity Method Investments [Line Items]

$ (399,965)

$ (412,084)

Investments In Affiliates Subsidiaries Associates And Joint Ventures net

1,307,725

1,310,478

^[1]

1,272,076

1,273,919

Schedule of Equity Method Investments [Line Items]

Square 407 Limited Partnership [Member]

$ (35,600)

(36,600)

Schedule of Equity Method Investments [Line Items]

Market Square North

50.00%

BP/CRF Metropolitan Square LLC [Member]

^[1]

$ (3,293)

(3,766)

Schedule of Equity Method Investments [Line Items]

Metropolitan Square

20.00%

901 New York Avenue LLC [Member]

^[1]

$ (12,971)

(13,584)

Schedule of Equity Method Investments [Line Items]

901 New York Avenue

^[2]

25.00%

901 New York Avenue LLC (economic ownership) [Member]

^[1]

$ (12,198)

$ (12,264)

Schedule of Equity Method Investments [Line Items]

WP Project Developer LLC [Member]

50.00%

Schedule of Equity Method Investments [Line Items]

Wisconsin Place Land and Infrastructure

^[3]

33.30%

Annapolis Junction NFM, LLC [Member]

^[1]

$ 34,887

$ 35,297

Schedule of Equity Method Investments [Line Items]

Annapolis Junction

50.00%

^[4]

50.00%

Schedule of Equity Method Investments [Line Items]

^[1]

13,463

540 Madison Venture

540 Madison Avenue

^[5]

60.00%

500 North Capitol Venture LLC [Member]

^[1]

122

Schedule of Equity Method Investments [Line Items]

500 North Capitol Street, NW

30.00%

501 K Street LLC [Member]

^[1]

$ (7,187)

(6,945)

Schedule of Equity Method Investments [Line Items]

1001 6th Street

^[6]

50.00%

Potential additonal payments to joint venture partner | payments

^[1]

$ 42,607

42,499

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]

$ 48,398

48,818

Schedule of Equity Method Investments [Line Items]

Hub50House

50.00%

Hotel Tower Developer LLC [Member]

^[1]

$ 49,520

50,943

Schedule of Equity Method Investments [Line Items]

The Hub on Causeway - Hotel Air Rights

50.00%

Office Tower Developer LLC [Member]

^[1]

$ 11,032

10,754

Schedule of Equity Method Investments [Line Items]

100 Causeway Street

50.00%

1265 Main Office JV LLC [Member]

^[1]

$ 56,458

56,312

Schedule of Equity Method Investments [Line Items]

1265 Main Street

50.00%

BNY Tower Holdings LLC [Member]

$ 3,899

3,787

^[1]

Schedule of Equity Method Investments [Line Items]

Dock 72

50.00%

BNYA Amenity Operator LLC [Member]

^[1]

$ 27,936

29,536

Schedule of Equity Method Investments [Line Items]

Dock 72

50.00%

CA-Colorado Center Limited Partnership [Member]

^[1]

$ 1,672

1,846

Schedule of Equity Method Investments [Line Items]

Colorado Center

50.00%

7750 Wisconsin Avenue LLC [Member]

^[1]

$ 229,094

227,671

Schedule of Equity Method Investments [Line Items]

7750 Wisconsin Avenue

50.00%

BP-M 3HB Venture LLC [Member]

^[1]

$ 58,697

58,112

Schedule of Equity Method Investments [Line Items]

3 Hudson Boulevard

25.00%

Schedule of Equity Method Investments [Line Items]

^[1]

$ 115,869

113,774

SMBP Venture LP [Member]

Santa Monica Business Park

55.00%

Platform 16 Holdings LP [Member]

^[1]

$ 159,545

145,761

Schedule of Equity Method Investments [Line Items]

Platform 16

^[7]

55.00%

Gateway Portfolio Holdings LLC [Member]

^[1]

$ 108,358

$ 108,393

Schedule of Equity Method Investments [Line Items]

Gateway Commons

50.00%

^[8]

54.00%

55.00%

Rosecrans-Sepulveda Partners 4, LLC

^[1]

$ 332,591

$ 336,206

Schedule of Equity Method Investments [Line Items]

Beach Cities Media Campus

50.00%

Entity Owning Land And Infrastructure Of Project [Member]

^[1]

$ 27,162

$ 27,184

Schedule of Equity Method Investments [Line Items]

Gateway Commons Complex prior to deferred contribution [Member] [Member]

33.30%

Schedule of Equity Method Investments [Line Items]

Gateway Commons Complex Future Development[Member] [Member]

54.00%

55.00%

Schedule of Equity Method Investments [Line Items]

Joint Venture Partner [Member] | Gateway Commons Complex Future Development[Member] [Member]

49.00%

Schedule of Equity Method Investments [Line Items]

Real estate and development in process, net

51.00%

[1]	Investments with deficit balances aggregating approximately $35.6 million and $36.6 million at March 31, 2021 and December 31, 2020, 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. At March 31, 2021 and December 31, 2020, the Company’s economic ownership was approximately 50%.
[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]	On March 30, 2021, the Company sold its interest in the joint venture to the partner. See below for additional details.
[5]	The property was sold on June 27, 2019. As of December 31, 2020, the investment consisted of undistributed cash. All remaining cash has been distributed as of March 31, 2021.
[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 2).
[8]	As a result of the partner’s deferred contribution, the Company owned an approximately 54% and 55% interest in the joint venture at March 31, 2021 and December 31, 2020, respectively. Future development projects will be owned 49% by the Company and 51% by its partner.

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

Mar. 31, 2021

Dec. 31, 2020

ASSETS

$ 17,873,023

$ 17,818,807

Total assets

22,213,552

22,858,190

Mortgage and notes payable, net

2,904,672

2,909,081

Members’/Partners’ equity

399,965

412,084

5,775,641

5,996,083

Total liabilities and equity / capital

22,213,552

22,858,190

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

1,307,725

1,310,478

237,017

237,393

Lease liabilities - finance leases

144,143

146,406

239,361

236,492

Lease liabilities - operating leases

200,383

201,713

Real estate and development in process, net

ASSETS

^[1]

4,711,593

4,708,571

Other assets

505,554

531,071

Total assets

5,217,147

5,239,642

Mortgage and notes payable, net

2,662,616

2,637,911

Members’/Partners’ equity

^[2]

599,354

650,433

1,955,177

1,951,298

Total liabilities and equity / capital

5,217,147

5,239,642

Company's share of equity

933,739

936,087

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

^[3]

338,337

337,832

^[4]

1,272,076

1,273,919

248,900

Lease liabilities - finance leases

22,200

22,500

387,900

388,700

Lease liabilities - operating leases

29,200

29,000

35,600

36,600

Colorado Center

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

306,903

307,328

^[5]

229,094

227,671

Gateway Commons Complex [Member]

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

50,682

51,875

^[5]

332,591

336,206

Dock 72

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

(51,708)

(52,243)

^[5]

$ 27,936

$ 29,536

[1]

At March 31, 2021 and December 31, 2020, this amount included right of use assets - finance leases totaling approximately $248.9 million and $248.9 million, respectively, and right of use assets - operating leases totaling approximately $22.2 million and $22.5 million, respectively.

[2]

At March 31, 2021 and December 31, 2020, this amount included lease liabilities - finance leases totaling approximately $387.9 million and $388.7 million, respectively, and lease liabilities - operating leases totaling approximately $29.2 million and $29.0 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. The Company’s basis differences are as follows:


	March 31, 2021		December 31, 2020
	(in thousands)
Property
Colorado Center	$	306,903	$	307,328
Gateway Commons	50,682		51,875
Dock 72	(51,708)		(52,243)

These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.

[4]

Investments with deficit balances aggregating approximately $35.6 million and $36.6 million at March 31, 2021 and December 31, 2020, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

[5]

Investments with deficit balances aggregating approximately $35.6 million and $36.6 million at March 31, 2021 and December 31, 2020, respectively, are included 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

Mar. 30, 2021

Mar. 31, 2021

Mar. 31, 2020

Schedule of Equity Method Investments [Line Items]

$ 713,695

$ 752,556

Expenses

331

615

176,565

171,094

484,800

481,187

Gains on sales of real estate

(107,902)

(101,591)

410,165

128,147

577,146

Write-off for accrued rent

5,225

(369)

600

1,200

Schedule of Equity Method Investments [Line Items]

^[1]

87,266

93,203

Expenses

Operating

37,134

35,401

34,103

32,035

71,244

67,436

(25,556)

(22,583)

Company's share of net income

(9,534)

3,184

(3,640)

1,252

10,257

^[2]

Basis differential

^[3]

(1,392)

(1,621)

Straight-line rent adjustments

5,225

(369)

1,100

9,700

Write-off for accrued rent

300

Colorado Center [Member]

Straight-line rent adjustments

500

Above and below market rent adjustments, net

$ 100

$ 300

540 Madison Avenue [Member]

Annapolis Junction NFM, LLC [Member]

^[4]

60.00%

$ 10,300

Schedule of Equity Method Investments [Line Items]

50.00%

^[5]

[1]	Includes straight-line rent adjustments of approximately $1.1 million and $9.7 million for the three months ended March 31, 2021 and 2020, respectively. For the three months ended March 31, 2021, write-offs of accounts receivable and accrued rent balances totaled approximately $0.3 million.
[2]	During the three months ended March 31, 2021, the Company completed the sale of its 50% ownership interest in Annapolis Junction NFM LLC. The Company recognized a gain on sale of investment of approximately $10.3 million.
[3]	Includes straight-line rent adjustments of approximately $0.5 million and $0.5 million for the three months ended March 31, 2021 and 2020, respectively. Also includes net above-/below-market rent adjustments of approximately $0.1 million and $0.3 million for the three months ended March 31, 2021 and 2020, respectively.
[4]	The property was sold on June 27, 2019. As of December 31, 2020, the investment consisted of undistributed cash. All remaining cash has been distributed as of March 31, 2021.
[5]	On March 30, 2021, the Company sold its interest in the joint venture to the partner. See below for additional details.

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

3 Months Ended

Apr. 01, 2021

USD ($)

Mar. 30, 2021

USD ($)

ft²

Jun. 30, 2021

USD ($)

Mar. 31, 2021

USD ($)

Mar. 31, 2020

USD ($)

Feb. 25, 2021

ft²

Dec. 31, 2020

USD ($)

Mortgage notes payable, net

$ 2,904,672

$ 2,909,081

Proceeds from Sale of Equity Method Investments

17,589

$ 0

Payments to Acquire Equity Method Investments

16,684

89,997

Capital distributions from unconsolidated joint ventures

5,225

(369)

122

Proceeds from sales of real estate

259,489

Repayments of Secured Debt

$ 5,374

4,212

Gateway Commons Complex [Member]

Schedule of Equity Method Investments [Line Items]

Gateway Commons Complex [Member] | Scenario, Plan

50.00%

^[1]

54.00%

55.00%

Schedule of Equity Method Investments [Line Items]

Gateway Commons Complex [Member] | Scenario, Plan | 751 Gateway

50.00%

Schedule of Equity Method Investments [Line Items]

Gateway Commons Complex prior to deferred contribution [Member] [Member]

49.00%

Schedule of Equity Method Investments [Line Items]

Gateway Commons Complex Future Development[Member] [Member]

54.00%

55.00%

Schedule of Equity Method Investments [Line Items]

Schedule of Equity Method Investments [Line Items]

49.00%

Platform 16

Annapolis Junction NFM, LLC [Member]

^[2]

55.00%

Schedule of Equity Method Investments [Line Items]

Proceeds from Sale of Equity Method Investments

50.00%

^[3]

Contractual Sales Price

$ 65,900

17,600

Repayments of Secured Debt

10,300

$ 10,300

$ 15,100

Annapolis Junction NFM, LLC [Member] | Subsequent Event [Member]

Schedule of Equity Method Investments [Line Items]

Proceeds from Sale of Equity Method Investments

$ 200

Capital distributions from unconsolidated joint ventures

$ 5,800

Annapolis Junction NFM, LLC [Member] | Annapolis Junction Building Six and Seven | Unconsolidated Properties

Schedule of Equity Method Investments [Line Items]

Net Rentable Area (in sf) | ft²

247,000

Joint Venture Partner [Member] | Gateway Commons Complex Future Development[Member] [Member]

Schedule of Equity Method Investments [Line Items]

51.00%

Schedule of Equity Method Investments [Line Items]

Mortgage notes payable, net

$ 2,662,616

$ 2,637,911

5,225

(369)

Construction in Progress | Gateway Commons Complex [Member] | 751 Gateway | Unconsolidated Properties

$ 10,257

^[4]

$ 0

Schedule of Equity Method Investments [Line Items]

Net Rentable Area (in sf) | ft²

229,000

[1]	As a result of the partner’s deferred contribution, the Company owned an approximately 54% and 55% interest in the joint venture at March 31, 2021 and December 31, 2020, respectively. Future development projects will be owned 49% by the Company and 51% by its partner.
[2]	This entity is a VIE (See Note 2).
[3]	On March 30, 2021, the Company sold its interest in the joint venture to the partner. See below for additional details.
[4]	During the three months ended March 31, 2021, the Company completed the sale of its 50% ownership interest in Annapolis Junction NFM LLC. The Company recognized a gain on sale of investment of approximately $10.3 million.

Mortgage Notes Payable, Net (Details) - USD ($) $ in Thousands		3 Months Ended
	Mar. 26, 2021	Mar. 31, 2021	Mar. 31, 2020
Debt Instrument [Line Items]
Repayments of Secured Debt		$ 5,374	$ 4,212
Mortgages [Member] \| University Place
Debt Instrument [Line Items]
Repayments of Secured Debt	$ 900
Debt Instrument, Interest Rate, Stated Percentage	6.94%

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

Mar. 31, 2021

Mar. 16, 2021

Feb. 14, 2021

Dec. 31, 2020

Senior Notes

$ 9,631,592

$ 9,639,287

Boston Properties Limited Partnership | Senior Notes

Senior Notes

9,631,592

$ 9,639,287

Debt Instrument, Unamortized Discount

9,700,000

18,736

Debt Issuance Costs, Net

49,672

Senior Notes

$ 9,631,592

Boston Properties Limited Partnership | Senior Notes | 3.954% unsecured senior notes

Debt Instrument, Interest Rate, Effective Percentage

3.85%

^[1]

3.954%

$ 1,000,000

Boston Properties Limited Partnership | Senior Notes | 3.279% unsecured senior notes

^[2]

Feb. 01, 2023

Debt Instrument, Interest Rate, Effective Percentage

3.125%

^[1]

3.279%

$ 500,000

Boston Properties Limited Partnership | Senior Notes | 3.916% unsecured senior notes

^[2]

Sep. 01, 2023

Debt Instrument, Interest Rate, Effective Percentage

3.80%

^[1]

3.916%

$ 700,000

Boston Properties Limited Partnership | Senior Notes | 3.350% unsecured senior notes

^[2]

Feb. 01, 2024

Debt Instrument, Interest Rate, Effective Percentage

3.20%

^[1]

3.35%

$ 850,000

Boston Properties Limited Partnership | Senior Notes | 3.766% unsecured senior notes

^[2]

Jan. 15, 2025

Debt Instrument, Interest Rate, Effective Percentage

3.65%

^[1]

3.766%

$ 1,000,000

Boston Properties Limited Partnership | Senior Notes | 3.495% unsecured senior notes

^[2]

Feb. 01, 2026

Debt Instrument, Interest Rate, Effective Percentage

2.75%

^[1]

3.495%

$ 1,000,000

Boston Properties Limited Partnership | Senior Notes | 4.628% unsecured senior notes

^[2]

Oct. 01, 2026

Debt Instrument, Interest Rate, Effective Percentage

4.50%

^[1]

4.628%

$ 1,000,000

Boston Properties Limited Partnership | Senior Notes | 3.505% unsecured senior notes

^[2]

Dec. 01, 2028

Debt Instrument, Interest Rate, Effective Percentage

3.40%

^[1]

3.505%

$ 850,000

Boston Properties Limited Partnership | Senior Notes | 2.984% unsecured senior notes

^[2]

Jun. 21, 2029

Debt Instrument, Interest Rate, Effective Percentage

2.90%

^[1]

2.984%

$ 700,000

Boston Properties Limited Partnership | Senior Notes | 3.343 % unsecured senior notes

^[2]

Mar. 15, 2030

Debt Instrument, Interest Rate, Effective Percentage

3.25%

^[1]

3.343%

$ 1,250,000

Boston Properties Limited Partnership | Senior Notes | 2.671% unsecured senior notes

^[2]

Jan. 30, 2031

Debt Instrument, Interest Rate, Effective Percentage

2.55%

2.671%

^[1]

2.671%

$ 850,000

Boston Properties Limited Partnership | Senior Notes | 4.289% unsecured senior notes

^[2]

Apr. 01, 2032

4.125%

$ 850,000

[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 (Narrative) (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 16, 2021

Feb. 14, 2021

Mar. 31, 2021

Mar. 31, 2020

Repayments of Unsecured Debt

$ 843,710

$ 0

Proceeds from unsecured senior notes

898

846,345

Repayments of Unsecured Debt

843,710

Proceeds from unsecured senior notes

898

$ 846,345

$ 0

Debt Instrument, Covenant Description

Debt Instrument, Covenant Compliance

At March 31, 2021, Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.

Senior Notes | Boston Properties Limited Partnership

2.671% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership

$ 9,700,000

$ 850,000

Debt Instrument, Interest Rate, Effective Percentage

2.55%

Senior Notes Pricing

99.57%

2.671%

^[1]

Proceeds from unsecured senior notes

$ 839,200

4.289% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership

$ 850,000

Repayments of Unsecured Debt

4.125%

$ 858,700

Debt Instrument, Increase, Accrued Interest

8,700

$ 400

[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 Line of Credit (Details) - USD ($) $ in Thousands		3 Months Ended
Unsecured Line of Credit (Details) - USD ($) $ in Thousands	Mar. 16, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Apr. 24, 2018	Apr. 24, 2017	Apr. 23, 2017
Line of Credit Facility [Line Items]
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.
Long-term Line of Credit		$ 0		$ 0
Loss from early extinguishment of debt		898	$ 0
Boston Properties Limited Partnership
Line of Credit Facility [Line Items]
Long-term Line of Credit		0		$ 0
Loss from early extinguishment of debt		898	$ 0
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
Revolving Credit Facility [Member] \| Boston Properties Limited Partnership
Line of Credit Facility [Line Items]
Long-term Line of Credit		$ 0
Delayed Draw Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity					$ 500,000	$ 500,000
Debt Instrument, Basis Spread on Variable Rate		0.95%
Loss from early extinguishment of debt	$ 500

Commitments And Contingencies (Details)	3 Months Ended
Commitments And Contingencies (Details)	Mar. 31, 2021 USD ($) ft²	Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations	$ 20,200,000
Notes Receivable, Related Parties	77,640,000	$ 77,552,000
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	$ 200,000,000
Coinsurance of program trigger	20.00%
Program trigger deductible	20.00%
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
Notes receivable, net	18,891,000	18,729,000
Affiliate of Bernstein Companies [Member]
Commitments And Contingencies [Line Items]
Notes receivable, net	$ 10,000,000.0
Note receivable fixed interest rate	8.00%
Boston Properties Limited Partnership
Commitments And Contingencies [Line Items]
Notes Receivable, Related Parties	$ 77,640,000	77,552,000
Operating partnership guarantee to cover liabilities of IXP	20,000,000.0
Notes receivable, net	18,891,000	$ 18,729,000
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation	23,100,000
Property insurance program per occurrence limits	1,625,000,000
7750 Wisconsin Avenue [Member]
Commitments And Contingencies [Line Items]
Liabilities for Contingent Guarantees	0
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
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
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
Future Retail Building [Member] \| 325 Main Street
Commitments And Contingencies [Line Items]
Net Rentable Area (in sf) \| ft²	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) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest in Limited Partnerships	$ 1,725,600	$ 1,726,933
Boston Properties Limited Partnership \| OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	16,053,640
Boston Properties Limited Partnership \| LTIP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	1,525,306
Boston Properties Limited Partnership \| 2012 OPP and 2013-2018 MYLTIP
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	451,043
Boston Properties Limited Partnership \| MYLTIP 2019 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	219,916
Boston Properties Limited Partnership \| MYLTIP 2020 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	203,278
Boston Properties Limited Partnership \| MYLTIP 2021
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	352,021

(Common Units) (Narrative) (Details) $ / shares in Units, $ in Thousands			3 Months Ended
	Feb. 05, 2021 USD ($) shares	Feb. 02, 2021 USD ($)	Mar. 31, 2021 USD ($) yr $ / shares shares	Dec. 31, 2020 USD ($)
Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount \| $			$ 1,780,044	$ 1,643,024
Unvested MYLTIP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
unvested MYLTIP distributions as compared to total distributions (percentage)			10.00%
MYLTIP 2018
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target	29.20%
Value of MYLTIP Awards \| $	$ 4,600
Forfeitures, in units	285,925
MYLTIP \| Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Vesting Period			3 years
MYLTIP 2019 [Member] \| Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding			219,916
MYLTIP 2020 [Member] \| Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding			203,278
MYLTIP 2021
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Value of MYLTIP Awards \| $		$ 15,300
Vesting Period		3 years
MYLTIP 2021 \| Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding			352,021
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares)			118,290
Restriction on redemption of OP Unit to Common Stock (in years) \| yr			1
Redemption of OP Unit equivalent to Common Stock (in shares)			1
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount \| $			$ 1,800,000
Closing price of common stock (in dollars per share) \| $ / shares			$ 101.26
Vested 2012 OPP units and MYLTIPS
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares)			64,799

Noncontrolling Interests Common Units Distributions (Details) - $ / shares	Jan. 28, 2021	Apr. 30, 2020	Jan. 30, 2020	Mar. 18, 2021
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit				$ 0.98
Dividends, Per Unit, Cash Paid	$ 0.98	$ 0.98	$ 0.98
Boston Properties Limited Partnership
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit				0.98
Dividends, Per Unit, Cash Paid	0.98	0.98	0.98
Boston Properties Limited Partnership \| Op units and LTIP units
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit				0.98
Dividends, Per Unit, Cash Paid	0.98	0.98	0.98
Boston Properties Limited Partnership \| Unvested MYLTIP Units [Member]
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit				$ 0.098
Dividends, Per Unit, Cash Paid	$ 0.098	$ 0.098	$ 0.098

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Noncontrolling Interest [Line Items]
Noncontrolling Interest in Limited Partnerships	$ 1,725,600	$ 1,726,933

Stockholders' Equity / Partners' Capital Narrative (Details) $ / shares in Units, $ in Thousands			3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) shares	May 22, 2020 USD ($) yr	Mar. 31, 2021 USD ($) shares	Mar. 31, 2020 USD ($)	Dec. 31, 2020 $ / shares shares	Mar. 02, 2021 $ / shares shares	Jun. 02, 2017 USD ($)
Class of Stock [Line Items]
Common Stock, Shares, Outstanding	156,074,200		156,074,200		155,718,825
General Partners' Capital Account, Units Outstanding (in units)	1,736,531		1,736,531
Limited Partners' Capital Account, Units Outstanding (in units)	154,337,669		154,337,669
Options exercised			206,377
Shares of Common Stock issued in connection with redemption of an equal number of OP Units (in shares)			118,290
Preferred Stock, Redemption Amount \| $	$ 193,623		$ 193,623
Preferred Stock Redemption Premium \| $			6,412	$ 0
ATM Program [Member]
Class of Stock [Line Items]
At The Market Stock Offering Program Aggregate Value Of Common Stock \| $		$ 600,000					$ 600,000
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
Preferred Stock, Redemption Price Per Share \| $ / shares						$ 2,500
Preferred Stock Redemption Price Per Share, plus accrued and unpaid dividends \| $ / shares						$ 2,516.41
Preferred Stock, Redemption Amount \| $	201,300		201,300
Redeemable Preferred Stock Dividends \| $	$ 1,300
Preferred Stock Redemption Premium \| $			$ 6,400
Depositary shares of Series B Cumulative Redeemable Preferred [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding (in shares)					8,000,000
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
Series B, Liquidation Preference Per Share (dollars per share) \| $ / shares					$ 2,500

Stockholders' Equity / Partners' Capital Dividends / Distributions (Details) - $ / shares	Feb. 16, 2021	Jan. 28, 2021	May 15, 2020	Apr. 30, 2020	Feb. 18, 2020	Jan. 30, 2020	Mar. 18, 2021
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit							$ 0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid		$ 0.98		$ 0.98		$ 0.98
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		$ 0.98		$ 0.98		$ 0.98
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Dividends / Distributions [Line Items]
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	$ 32.8125		$ 32.8125		$ 32.8125

Segment Information Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Write-off for accrued rent	$ 600	$ 1,200
Write-off for accounts receivable		$ 300
Write off of accounts receivable	(200)
Parking and Other [Member]
Segment Reporting Information [Line Items]
Increase (decrease) in parking and other revenue primarily related to COVID-19	$ (7,600)

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	$ 91,624	$ 497,496
Preferred Stock Redemption Charge	(6,412)	0
Preferred dividends / distributions	(2,560)	(2,625)
Noncontrolling interest-common units of the Operating Partnership	(11,084)	(57,539)
Noncontrolling interest in property partnerships	(16,467)	(19,486)
Interest expense	(107,902)	(101,591)
Loss from early extinguishment of debt	898	0
Company's share of net operating income from joint ventures	(443,947)	(471,653)
Depreciation and amortization expense	(176,565)	(171,094)
Transaction costs	(331)	(615)
General and administrative expense	(44,959)	(36,454)
Gains (losses) from investments in securities	(1,659)	5,445
Interest and other income (loss)	(1,168)	(3,017)
Gains on sales of real estate	0	(410,165)
Income (loss) from unconsolidated joint ventures	(5,225)	369
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	91,624	497,496
Preferred Stock Redemption Charge	6,412	0
Preferred dividends / distributions	2,560	2,625
Noncontrolling interest-common units of the Operating Partnership	11,084	57,539
Noncontrolling interest in property partnerships	16,467	19,486
Interest expense	107,902	101,591
Loss from early extinguishment of debt	898	0
Depreciation and amortization expense	176,565	171,094
Transaction costs	331	615
Operating expense	3,505	3,237
General and administrative expense	44,959	36,454
Gains (losses) from investments in securities	1,659	(5,445)
Interest and other income (loss)	1,168	3,017
Gains on sales of real estate	0	410,165
Income (loss) from unconsolidated joint ventures	5,225	(369)
Other revenue	3,505	3,237
Company's share of Net Operating Income	424,366	452,750
Unconsolidated Joint Ventures [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense	(25,556)	(22,583)
Company's share of net operating income from joint ventures	(24,795)	(28,758)
Depreciation and amortization expense	(34,103)	(32,035)
Transaction costs	(7)	0
Income (loss) from unconsolidated joint ventures	(5,225)	369
Unconsolidated Joint Ventures [Member] \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	24,795	28,758
Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	105,773	566,333
Preferred Stock Redemption Charge	(6,412)	0
Preferred dividends / distributions	(2,560)	(2,625)
Noncontrolling interest in property partnerships	(16,467)	(19,486)
Interest expense	(107,902)	(101,591)
Loss from early extinguishment of debt	898	0
Depreciation and amortization expense	(173,500)	(169,285)
Transaction costs	(331)	(615)
General and administrative expense	(44,959)	(36,454)
Gains (losses) from investments in securities	(1,659)	5,445
Interest and other income (loss)	(1,168)	(3,017)
Gains on sales of real estate	0	(419,654)
Income (loss) from unconsolidated joint ventures	(5,225)	369
Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company's common shareholders / unitholders	105,773	566,333
Preferred Stock Redemption Charge	6,412	0
Preferred dividends / distributions	2,560	2,625
Noncontrolling interest in property partnerships	16,467	19,486
Interest expense	107,902	101,591
Loss from early extinguishment of debt	898	0
Depreciation and amortization expense	173,500	169,285
Transaction costs	331	615
Operating expense	3,505	3,237
General and administrative expense	44,959	36,454
Gains (losses) from investments in securities	1,659	(5,445)
Interest and other income (loss)	1,168	3,017
Gains on sales of real estate	0	419,654
Income (loss) from unconsolidated joint ventures	5,225	(369)
Other revenue	3,505	3,237
Company's share of Net Operating Income	424,366	452,750
Management Service [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	(6,803)	(7,879)
Management Service [Member] \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	6,803	7,879
Management Service [Member] \| Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Operating expense	(3,505)	(3,237)
Other revenue	(6,803)	(7,879)
Management Service [Member] \| Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	6,803	7,879
Noncontrolling interest - property partnerships [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	44,376	47,661
Noncontrolling interest - property partnerships [Member] \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	44,376	47,661
Noncontrolling interest - property partnerships [Member] \| Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	$ 44,376	$ 47,661

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

3 Months Ended

Mar. 31, 2021

Mar. 31, 2020

^[1]

$ 693,580

$ 724,659

^[1]

9,175

9,956

^[1]

$ 703,387

$ 741,440

^[1]

100.00%

$ 251,262

$ 258,902

6,127

4,064

$ 259,440

$ 269,787

100.00%

$ 443,947

$ 471,653

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

100.00%

100.00%

$ 713,695

$ 752,556

Boston [Member]

^[1]

230,403

239,498

^[1]

3,045

4,068

^[1]

$ 234,080

$ 250,391

^[1]

33.28%

33.77%

$ 79,881

$ 82,545

1,455

1,340

$ 83,387

$ 90,706

32.14%

33.62%

$ 150,693

$ 159,685

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

33.94%

33.85%

33.64%

33.60%

Los Angeles [Member]

^[1]

$ 0

^[1]

^[1]

$ 0

^[1]

0.00%

$ 0

$ 0

0.00%

$ 0

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

0.00%

3.34%

3.52%

New York [Member]

^[1]

$ 250,164

$ 255,286

^[1]

^[1]

$ 250,164

$ 255,286

^[1]

35.57%

34.43%

$ 99,385

$ 99,140

$ 99,385

$ 99,140

38.31%

36.75%

$ 150,779

$ 156,146

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

33.97%

33.11%

27.30%

26.48%

San Francisco [Member]

^[1]

$ 130,598

$ 136,739

^[1]

321

^[1]

$ 130,919

$ 136,739

^[1]

18.61%

18.44%

$ 40,249

$ 42,569

1,686

$ 41,935

$ 42,569

16.16%

15.78%

$ 88,984

$ 94,170

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

20.04%

19.97%

21.79%

21.50%

Washington, DC [Member]

^[1]

$ 82,415

$ 93,136

^[1]

5,809

5,888

^[1]

$ 88,224

$ 99,024

^[1]

12.54%

13.36%

$ 31,747

$ 34,648

2,986

2,724

$ 34,733

$ 37,372

13.39%

13.85%

$ 53,491

$ 61,652

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

12.05%

13.07%

13.93%

14.90%

Hotel [Member]

^[1]

$ 632

$ 6,825

Hotel [Member] | Boston [Member]

2,051

6,821

^[1]

632

6,825

Hotel [Member] | Los Angeles [Member]

2,051

6,821

^[1]

Hotel [Member] | New York [Member]

^[1]

Hotel [Member] | San Francisco [Member]

^[1]

Hotel [Member] | Washington, DC [Member]

^[1]

Noncontrolling interest - property partnerships [Member]

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

(44,376)

(47,661)

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

(10,224)

(10,663)

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

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

(34,152)

(36,998)

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

24,795

28,758

Unconsolidated Joint Ventures [Member] | Boston [Member]

^[2]

87,266

93,203

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

2,281

3,099

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

14,192

15,930

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

(793)

756

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

3,480

3,159

5,635

5,814

Company's Share [Member]

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

424,366

452,750

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

142,750

152,121

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

14,192

15,930

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

115,834

119,904

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

92,464

97,329