0001656423-22-000013 | 10-K | XBRL Viewer

General and administrative

^[1]

383,649,000

319,560,000

322,817,000

Expenses

Rental

1,021,151,000

1,017,208,000

1,050,010,000

151,573,000

133,112,000

140,777,000

Depreciation and amortization

470,000

1,027,000

1,000,000

147,121,000

141,853,000

102,296,000

Total expenses

306,089,000

287,227,000

226,288,000

Income (Loss) from Unconsolidated Joint Ventures

(2,570,000)

(85,110,000)

46,592,000

Interest and other income (loss)

11,737,000

^[2]

32,706,000

^[2]

5,704,000

5,953,000

18,939,000

Gains from investments in securities

5,626,000

5,261,000

6,417,000

Impairment loss

(22,272,000)

(45,182,000)

(29,540,000)

(108,884,000)

(98,051,000)

(84,409,000)

Net income attributable to noncontrolling interests

(31,324,000)

(53,981,000)

44,826,000

Noncontrolling interests in property partnerships

(70,806,000)

(48,260,000)

(71,120,000)

Noncontrolling interest - common units of the Operating Partnership

(55,931,000)

(97,704,000)

(59,345,000)

Net income attributable to the Company

570,965,000

990,479,000

590,602,000

Preferred dividends / distributions

(2,560,000)

(10,500,000)

Preferred Stock Redemption Charge

(6,412,000)

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

$ 561,993,000

$ 979,979,000

$ 580,102,000

Basic earnings per common share / unit attributable to the Company

Earnings Per Share After Allocation of Undistributed Earnings to Participating Securities Basic (dollars per share)

$ 3.25

$ 5.67

$ 3.37

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

173,150

172,643

172,200

Diluted earnings per common share / unit attributable to the Company

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

$ 3.24

$ 5.67

$ 3.36

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

173,410

172,728

172,501

Parking and Other [Member]

Revenue

$ 81,814,000

$ 70,680,000

$ 103,534,000

Hotel [Member]

Revenue

Real Estate, Other [Member]

13,609,000

7,478,000

48,589,000

Expenses

Operating expense

12,998,000

13,136,000

34,004,000

Revenue

Management Service [Member]

12,487,000

11,626,000

10,386,000

Expenses

Operating expense

12,487,000

11,626,000

10,386,000

Revenue

$ 27,697,000

$ 29,641,000

$ 40,039,000

[1]

Includes straight-line rent adjustments of approximately $17.2 million, $(10.1) million and $32.4 million for the years ended December 31, 2021, 2020 and 2019, respectively

[2]

For the year ended December 31, 2020, represents the gain on sale of Annapolis Junction Building Eight and two land parcels. For the year ended December 31, 2019, represents the gain on sale of 540 Madison Avenue recognized by the joint venture. During 2008, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture resulting in a basis differential between the carrying value of the Company’s investment in the joint venture and the joint venture’s basis in the assets and liabilities of the property. As a result of the historical basis difference, the Company recognized a gain on sale of real estate totaling approximately $47.2 million for the year ended December 31, 2019, which consists of its share of the gain on sale reported by the joint venture as well as an adjustment for the basis differential. The gain on sale of real estate is included in Income (loss) from Unconsolidated Joint Ventures in the Company’s Consolidated Statements of Operations.

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

12 Months Ended

Dec. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

Effective portion of interest rate contracts

$ (31,324)

$ (53,981)

$ 44,826

Other comprehensive income (loss):

8,544

(7,848)

(6,751)

Amortization of interest rate contracts

^[1]

6,704

6,697

6,664

Other comprehensive income (loss)

15,248

(1,151)

(87)

Comprehensive Income

657,019

1,037,588

661,635

Net income attributable to noncontrolling interests

(71,382)

(48,836)

(71,696)

Other comprehensive income attributable to noncontrolling interests

(2,020)

(404)

(507)

Comprehensive income attributable to the Company

$ 585,637

$ 988,752

$ 589,939

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

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income (loss) and other comprehensive income (loss), attributable to noncontrolling interests. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References + Details

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References + Details

Amount after tax and reclassification adjustments of other comprehensive income (loss).

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The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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Basis Of Presentation And Summary Of Significant Accounting Policies

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]	Noncontrolling interest - property partnerships [Member] Cumulative Effect, Period of Adoption, Adjustment
Equity, shares at Dec. 31, 2018			154,458,000
Equity, value at Dec. 31, 2018	$ 8,213,968	$ (4,379)	$ 1,545	$ 200,000	$ 6,407,623	$ (675,534)	$ (3,864)	$ (2,722)	$ (47,741)	$ 619,352	$ (445)	$ 1,711,445	$ (70)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List] \| Accounting Standards Update 2018-09	us-gaap:AccountingStandardsUpdate201409Member
Accounting Standards Update [Extensible List] \| Accounting Standards Update 2016-02	us-gaap:AccountingStandardsUpdate201409Member
Redemption of operating partnership units to common stock, shares			145,000
Redemption of operating partnership units to common stock, value	$ 0		$ 2		4,883					(4,885)
Allocated net income for the year	651,999					521,534				59,345		71,120
Dividends/distributions declared	(671,893)					(602,659)				(69,234)
Shares issued pursuant to stock purchase plan, shares			6,000
Shares issued pursuant to stock purchase plan, value	688				688
Net activity from stock option and incentive plan, shares			181,000
Net activity from stock option and incentive plan, value	45,000		$ 1		8,771					36,228
Sale of an interest in property partnerships	0				(4,216)							4,216
Acquisition of noncontrolling interest in property partnership	(186,963)				(162,462)							(24,501)
Issuance of operating partnership units for 360 Park Avenue South	0
Preferred Stock Redemption Charge	0
Contributions from noncontrolling interests in property partnerships	35,816											35,816
Distributions to noncontrolling interests in property partnerships	69,913											(69,913)
Effective portion of interest rate contracts	(6,751)								(6,060)	(691)
Amortization of interest rate contracts	6,664								5,466	622		576
Reallocation of noncontrolling interest	0				39,432					(39,432)
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]
Accounting Standards Update [Extensible List] \| Accounting Standards Update 2018-09	us-gaap:AccountingStandardsUpdate201409Member
Redemption of operating partnership units to common stock, shares			857,000
Redemption of operating partnership units to common stock, value	$ 0		$ 9		29,689					(29,698)
Allocated net income for the year	1,018,691					872,727				97,704		48,260
Dividends/distributions declared	(689,273)					(620,352)				(68,921)
Shares issued pursuant to stock purchase plan, shares			7,000
Shares issued pursuant to stock purchase plan, value	759				759
Net activity from stock option and incentive plan, shares			65,000
Net activity from stock option and incentive plan, value	48,621				9,303					39,318
Issuance of operating partnership units for 360 Park Avenue South	0
Preferred Stock Redemption Charge	0
Contributions from noncontrolling interests in property partnerships	8,219											8,219
Distributions to noncontrolling interests in property partnerships	(58,811)											(58,811)
Effective portion of interest rate contracts	(7,848)								(7,066)	(782)
Amortization of interest rate contracts	6,697								5,511	610		576
Reallocation of noncontrolling interest	$ 0				22,321					(22,321)
Equity, shares at Dec. 31, 2020	155,718,825		155,719,000
Equity, value at Dec. 31, 2020	$ 6,425,305		$ 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			524,000
Redemption of operating partnership units to common stock, value	0		$ 5		18,381					(18,386)
Allocated net income for the year	631,932					505,195				55,931		70,806
Dividends/distributions declared	(683,843)					(615,021)				(68,822)
Shares issued pursuant to stock purchase plan, shares			9,000
Shares issued pursuant to stock purchase plan, value	1,004				1,004
Net activity from stock option and incentive plan, shares			293,000
Net activity from stock option and incentive plan, value	71,383		$ 3		25,607					45,773
Issuance of operating partnership units for 360 Park Avenue South	99,689									99,689
Preferred Stock, Redeemed	(193,623)			(200,000)	6,377
Preferred Stock Redemption Charge	(6,412)					(6,412)
Contributions from noncontrolling interests in property partnerships	18,002											18,002
Distributions to noncontrolling interests in property partnerships	(259,764)											(259,764)
Effective portion of interest rate contracts	8,544								7,703	841
Amortization of interest rate contracts	6,704								5,525	603		576
Reallocation of noncontrolling interest	$ 0				89,570					(89,570)
Equity, shares at Dec. 31, 2021	156,544,849		156,545,000
Equity, value at Dec. 31, 2021	$ 5,693,181		$ 1,565	$ 0	$ 6,497,730	$ (625,891)		$ (2,722)	$ (36,662)	$ 642,655		$ 1,556,553

Consolidated Statement of Capital and Noncontrolling Interests - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Common Stock, Shares, Outstanding	156,544,849	155,718,825
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount	$ 2,078,603	$ 1,643,024
Net activity from stock option and incentive plan, value	71,383	48,621	$ 45,000
Preferred Stock Redemption Charge	(6,412)	0	0
Effective portion of interest rate contracts	8,544	(7,848)	(6,751)
Amortization of interest rate contracts	6,704	6,697	6,664
Acquisition of noncontrolling interest in property partnership			(186,963)
Sale of an interest in property partnerships			0
Contributions from noncontrolling interests in property partnerships	18,002	8,219	35,816
Distributions to noncontrolling interests in property partnerships	(259,764)	(58,811)	69,913
Issuance of operating partnership units for 360 Park Avenue South	$ 99,689	$ 0	$ 0
Accounting Standards Update 2016-02
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201409Member
Accounting Standards Update 2018-09
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201409Member	us-gaap:AccountingStandardsUpdate201409Member
General Partner [Member]
Common Stock, Shares, Outstanding	1,746,000	1,731,000	1,727,000	1,722,000
Net activity from stock option and incentive plan, shares	5,000	1,000	3,000
Conversion of redeemable partnership units	10,000	3,000	2,000
Limited Partner [Member]
Common Stock, Shares, Outstanding	154,799,000	153,988,000	153,063,000	152,736,000
Net activity from stock option and incentive plan, shares	295,000	72,000	185,000
Conversion of redeemable partnership units	516,000	853,000	142,000
Partners' Capital (General and Limited Partners)[Member]
Beginning Balance	$ 4,173,290	$ 4,554,639	$ 3,380,175	$ 4,054,996
Net activity from stock option and incentive plan, value	26,614	10,062	9,460
Allocated net income for the period	512,474	882,275	520,757
Distributions	(612,461)	(609,852)	(592,159)
Preferred Stock Redemption Charge	(6,412)
Conversion of redeemable partnership units, value	18,386	29,689	4,885
Adjustment to reflect redeemable partnership units at redemption value	(319,950)	863,795	(447,222)
Acquisition of noncontrolling interest in property partnership			(162,462)
Sale of an interest in property partnerships			(4,216)
Partners' Capital (General and Limited Partners)[Member] \| Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance			(1,505)	(3,864)
Preferred Units [Member]
Beginning Balance	0	193,623	193,623	193,623
Allocated net income for the period	2,560	10,500	10,500
Distributions	(2,560)	(10,500)	(10,500)
Preferred Units [Member] \| Boston Properties Limited Partnership
Preferred Stock, Redemption Amount	(193,623)
Accumulated Other Comprehensive Loss [Member]
Beginning Balance	(36,662)	(49,890)	(48,335)	(47,741)
Effective portion of interest rate contracts	7,703	(7,066)	(6,060)
Amortization of interest rate contracts	5,525	5,511	5,466
Noncontrolling interest - property partnerships [Member]
Beginning Balance	1,556,553	1,726,933	1,728,689	1,711,445
Allocated net income for the period	70,806	48,260	71,120
Amortization of interest rate contracts	576	576	576
Acquisition of noncontrolling interest in property partnership			(24,501)
Sale of an interest in property partnerships			4,216
Contributions from noncontrolling interests in property partnerships	18,002	8,219	35,816
Distributions to noncontrolling interests in property partnerships	(259,764)	(58,811)	(69,913)
Noncontrolling interest - property partnerships [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance				(70)
Total Capital [Member]
Beginning Balance	5,693,181	6,425,305	5,254,152	5,912,323
Net activity from stock option and incentive plan, value	26,614	10,062	9,460
Allocated net income for the period	585,840	941,035	602,377
Distributions	(615,021)	(620,352)	(602,659)
Preferred Stock, Redemption Amount	(193,623)
Preferred Stock Redemption Charge	(6,412)
Conversion of redeemable partnership units, value	18,386	29,689	4,885
Adjustment to reflect redeemable partnership units at redemption value	(319,950)	863,795	(447,222)
Effective portion of interest rate contracts	7,703	(7,066)	(6,060)
Amortization of interest rate contracts	6,101	6,087	6,042
Acquisition of noncontrolling interest in property partnership			(186,963)
Sale of an interest in property partnerships			0
Contributions from noncontrolling interests in property partnerships	18,002	8,219	35,816
Distributions to noncontrolling interests in property partnerships	(259,764)	(58,811)	(69,913)
Total Capital [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance			(1,505)	(3,934)
Noncontrolling interest - Redeemable partnership units [Member]
Beginning Balance	2,078,603	1,643,024	2,468,753	2,000,591
Net activity from stock option and incentive plan, value	45,773	39,318	36,228
Allocated net income for the period	55,931	97,704	59,345
Distributions	(68,822)	(68,921)	69,234
Conversion of redeemable partnership units, value	(18,386)	(29,689)	(4,885)
Adjustment to reflect redeemable partnership units at redemption value	319,950	(863,795)	447,222
Effective portion of interest rate contracts	841	(782)	(691)
Amortization of interest rate contracts	603	$ 610	622
Issuance of operating partnership units for 360 Park Avenue South	$ 99,689
Noncontrolling interest - Redeemable partnership units [Member] \| Cumulative Effect, Period of Adoption, Adjustment
Beginning Balance			$ (174)	$ (445)

Organization	12 Months Ended
Organization	Dec. 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 December 31, 2021 owned an approximate 89.7% (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 11, 16 and 18). 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. 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. 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. 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 and all of the outstanding Depositary Shares. In connection with the redemption of the Series B Preferred Stock, the Series B Preferred Units were also redeemed (See Note 12). Properties At December 31, 2021, the Company owned or had joint venture interests in a portfolio of 201 commercial real estate properties (the “Properties”) aggregating approximately 52.8 million net rentable square feet of primarily Class A office properties, including nine properties under construction/redevelopment totaling approximately 3.4 million net rentable square feet. At December 31, 2021, the Properties consisted of: •182 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. All references to acres and square footage in the Notes are unaudited. Basis of Presentation The accompanying consolidated financial statements are presented using the accrual basis of accounting in conformity with accounting principles generally accepted in the United States of America. Boston Properties, Inc. does not have any other significant assets, liabilities or operations, other than its investment in Boston Properties Limited Partnership, nor does it have employees of its own. Boston Properties Limited Partnership, not Boston Properties, Inc., generally executes all significant business relationships other than transactions involving securities of Boston Properties, Inc. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income. Variable Interest Entities (VIEs) Consolidated VIEs are those for which the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE. The Company has determined that it is the primary beneficiary for six of the seven entities that are VIEs as of December 31, 2021. Consolidated Variable Interest Entities As of December 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 11). 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 As of December 31, 2021, 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.

Summary Of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

2. Summary of Significant Accounting Policies

Real Estate

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

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

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

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

Management reviews its long-lived assets for indicators of impairment following the end of each quarter and when events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. This evaluation of long-lived assets is dependent on a number of factors, including when there is an event or adverse change in the operating performance of the long-lived asset or a current expectation that, more likely than not, a long-lived asset will be sold or otherwise disposed of significantly before the end of its previously estimated useful life or hold period. An impairment loss is recognized if the carrying amount of an asset is not recoverable and exceeds its fair value. The evaluation of anticipated cash flows is subjective and is based in part on assumptions regarding anticipated hold periods, future occupancy, future rental rates, future capital requirements, discount rates and capitalization rates that could differ materially from actual results in future periods. Because cash flows on properties considered to be “long-lived assets to be held and used” are considered on an undiscounted basis to determine whether an asset may be impaired, the Company’s established strategy of holding properties over the long term directly decreases the likelihood of recording an impairment loss. If the Company’s hold strategy changes or market conditions otherwise dictate an earlier sale date, an impairment loss may be recognized, and such loss could be material. If the Company determines that an impairment has occurred, the affected assets must be reduced to their fair value.

Guidance in Accounting Standards Codification (“ASC”) 360 “Property Plant and Equipment” requires that qualifying assets and liabilities and the results of operations that have been sold, or otherwise qualify as “held for sale,” be presented as discontinued operations in all periods presented if the property operations are expected to be eliminated and the Company will not have significant continuing involvement following the sale. Discontinued operations presentation applies only to disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results (e.g., a disposal of a major geographical area, a major line of business, a major equity method investment or other major parts of an entity). The components of the property’s net income that are reflected as discontinued operations include the net gain (or loss) upon the disposition of the property held for sale, operating results, depreciation and interest expense (if the property is subject to a secured loan). The Company generally considers assets to be “held for sale” when the transaction has been approved by Boston Properties, Inc.’s Board of Directors, or a committee thereof, and there are no known significant contingencies relating to the sale, such that a sale of the property within one year is considered probable. Following the classification of a property as “held for sale,” no further depreciation is recorded on the assets, and the asset is written down to the lower of carrying value or fair market value, less cost to sell.

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

Capitalized costs include pre-construction costs necessary to the development of the property, development costs (including architectural, engineering and design costs), construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. The Company begins the capitalization of costs during the pre-construction period, which it defines as activities that are necessary for the development of the property. The Company considers a construction project as substantially complete and held available for occupancy upon the completion of tenant improvements, but no later than one year from cessation of major construction activity. The Company ceases capitalization on the portion (1) substantially completed, (2) occupied or held available for occupancy, and capitalizes only those costs associated with the portion under construction or (3) if activities necessary for the development of the property have been suspended. Interest costs capitalized for the years ended December 31, 2021, 2020 and 2019 were approximately $53.1 million, $53.9 million and $54.9 million, respectively. Salaries and related costs capitalized for the years ended December 31, 2021, 2020 and 2019 were approximately $13.7 million, $12.9 million and $10.4 million, respectively.

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

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

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



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

Cash and Cash Equivalents

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

Cash Held in Escrows

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

Investments in Securities

The Company accounts for investments in equity securities at fair value, with gains or losses resulting from changes in fair value recognized currently in earnings. The Company maintains deferred compensation plans that are designed to allow officers and non-employee directors of Boston Properties, Inc. to defer a portion of the officer’s current income or the non-employee director’s current compensation on a pre-tax basis and receive a tax-deferred return on these deferrals based on the performance of specific investments selected by the officer or non-employee director. The Company’s obligation under the plans is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2021 and 2020, the Company had maintained approximately $43.6 million and $39.5 million, respectively, in separate accounts, which are not restricted as to their use. The Company recognized gains of approximately $5.6 million, $5.3 million and $6.4 million on its investments in the accounts associated with the Company’s deferred compensation plans during the years ended December 31, 2021, 2020 and 2019, respectively.

Tenant and Other Receivables

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

Notes Receivable

The Company accounts for notes receivable at their unamortized cost, net of any unamortized deferred fees or costs, premiums or discounts and an allowance for loan losses. Loan fees and direct costs associated with loans originated by the Company are deferred and amortized over the term of the note as interest income.

Deferred Charges

Deferred charges include leasing costs and certain financing fees. Leasing costs include acquired intangible in-place lease values and direct and incremental fees and costs incurred in the successful negotiation of leases, including brokerage and other costs which have been deferred and are being amortized on a straight-line basis over the terms of the respective leases. Unamortized leasing costs are charged to expense upon the early termination of the lease. Fully amortized deferred leasing costs are removed from the books upon the expiration of the lease. Financing fees included in deferred charges consist of external fees and costs incurred to obtain the Company’s revolving facility and if applicable, the delayed draw facility and construction financing arrangements where there are not sufficient amounts outstanding to report the fees net of the debt liability. Such financing costs have been deferred and are being amortized over the terms of the respective financing and included within interest expense. Unamortized financing costs are charged to expense upon the early repayment or significant modification of the financing. Fully amortized deferred financing costs are removed from the books upon the maturity of the debt.

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

Investments in Unconsolidated Joint Ventures

The Company consolidates VIEs in which it is considered to be the primary beneficiary. VIEs are entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial

support or that the holders of the equity investment at risk do not have substantive participating rights. The primary beneficiary is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the variable interest entity’s performance, and (2) the obligation to absorb losses and the right to receive the returns from the variable interest entity that could potentially be significant to the VIE. For ventures that are not VIEs, the Company consolidates entities for which it has significant decision making control over the ventures’ operations. The Company’s judgment with respect to its level of influence or control of an entity involves the consideration of various factors including the form of the Company’s ownership interest, its representation in the entity’s governance, the size of its investment (including loans), estimates of future cash flows, its ability to participate in policy making decisions and the rights of the other investors to participate in the decision making process and to replace the Company as manager and/or liquidate the venture, if applicable. The Company’s assessment of its influence or control over an entity affects the presentation of these investments in the Company’s consolidated financial statements. In addition to evaluating control rights, the Company consolidates entities in which the outside partner has no substantive kick-out rights to remove the Company as the managing member.

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

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

The combined summarized financial information of the unconsolidated joint ventures is disclosed in Note 6.

Revenue Recognition

In general, the Company commences lease/rental revenue recognition when the tenant takes possession of the leased space and the leased space is substantially ready for its intended use. Contractual lease/rental revenue is reported on a straight-line basis over the terms of the respective leases. The impact of the straight-line rent adjustment increased revenue by approximately $104.3 million, $104.9 million and $58.4 million for the years ended

December 31, 2021, 2020 and 2019, respectively, as the revenue recorded exceeded amounts billed. Accrued rental income, as reported on the Consolidated Balance Sheets, represents cumulative lease/rental income earned in excess of rent payments received pursuant to the terms of the individual lease agreements.

The Company must estimate the collectability of its accrued rent and accounts receivable balances related to lease revenue. When evaluating the collectability of tenants’ accrued rent and accounts receivable balances, management considers tenant creditworthiness, current economic trends, including the impact of COVID-19 pandemic on tenants’ businesses, and changes in tenants’ payment patterns, on a lease-by-lease basis. The Company writes-off the tenant’s receivable balance, including the accrued rent receivable, if the Company considers the balances no longer probable of collection. In addition, tenants in bankruptcy are analyzed and considerations are made in connection with the expected recovery of pre-petition and post-petition claims. If the Company deems the balances no longer probable of collection, the Company writes them off and ceases recognizing lease income, including straight-line rent, unless cash is received (See Note 4). Following a write-off, if (1) the Company subsequently determines that it is probable it will collect substantially all the remaining lessee’s lease payments under the lease term and (2) the lease has not been modified since the write-off, the Company will then reinstate the accrued rent and accounts receivable write-offs, adjusting for the amount related to the period when the lease payments were considered not probable of collection. If the Company’s estimates of collectability differs from the cash received, then the timing and amount of the Company’s reported revenue could be impacted. The credit risk is mitigated by the high quality of the Company’s existing tenant base, reviews of prospective tenants’ risk profiles prior to lease execution and consistent monitoring of the Company’s portfolio to identify potential problem tenants.

The Company recognizes acquired in-place “above-” and “below-market” leases at their fair values as rental revenue over the original term of the respective leases. The impact of the acquired in-place “above-” and “below-market” leases increased revenue by approximately $4.2 million, $6.5 million and $20.9 million for the years ended December 31, 2021, 2020 and 2019, respectively. The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).


	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2022	$	428	$	7,119
2023	208		5,334
2024	147		3,806
2025	135		3,775
2026	135		2,843

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

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

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

The Company earns management and development fees. Development and management services revenue is earned from unconsolidated joint venture entities and third-party property owners. The Company determined that the performance obligations associated with its development services contracts are satisfied over time and that the Company would recognize its development services revenue under the output method evenly over time from the development commencement date through the substantial completion date of the development management

services project due to the stand-ready nature of the contracts. Significant judgments impacting the amount and timing of revenue recognized from the Company’s development services contracts include estimates of total development project costs from which the fees are typically derived and estimates of the period of time until substantial completion of the development project, the period of time over which the development services are required to be performed. The Company recognizes development fees earned from unconsolidated joint venture projects equal to its cost plus profit to the extent of the third party partners’ ownership interest. Property management fees are recorded and earned based on a percentage of collected rents at the properties under management, and not on a straight-line basis, because such fees are contingent upon the collection of rents.

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

Leases

Lessee

For leases in which the Company is the lessee (generally ground leases), in accordance with ASC 842 the Company recognizes a right-of-use asset and a lease liability. The Company made the policy election to not apply the requirements of ASC 842 to short-term leases. This policy election is made by class of underlying assets and as described below, the Company considers real estate to be a class of underlying assets, and will not be further delineating it into specific uses of the real estate asset as the risk profiles are similar in nature. The Company will recognize the lease payments it pays in net income on a straight-line basis over the lease term.

The lease liability is equal to the present value of the minimum lease payments in accordance with ASC 842. The Company will use its incremental borrowing rate (“IBR”) to determine the net present value of the minimum lease payments. In order to determine the IBR, the Company utilized a market-based approach to estimate the incremental borrowing rate for each individual lease. The approach required significant judgment. Therefore, the Company utilized different data sets to estimate base IBRs via an analysis of the following weighted-components:

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

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

•unlevered property yields and discount rates.

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

Lessor

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

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

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

The Company assessed and concluded that the timing and pattern of transfer for nonlease components and the associated lease component are the same. The Company determined that the predominant component was the lease component and as such its leases will continue to qualify as operating leases and the Company has made a policy election to account for and present the lease component and the nonlease component as a single component in the revenue section of the Consolidated Statements of Operations labeled Lease.

Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized as revenue in the period during which the expenses are incurred. The Company recognizes these reimbursements on a gross basis, as the Company obtains control of the goods and services before they are transferred to the tenant.

In addition, in accordance with ASC 842, lessors will only capitalize incremental direct leasing costs.

Earnings Per Share

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

Earnings Per Common Unit

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

Recurring 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 for December 31, 2021 and 2020, the financial instruments that are being valued for disclosure purposes as well as the Level at which they are categorized as defined in 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			Level 3
Unsecured term loan (2)			Level 3

_______________

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

(2) As of December 31, 2021, the unsecured term loan had been repaid and was no longer outstanding.

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.

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 December 31, 2021 and December 31, 2020 (in thousands):


	December 31, 2021				December 31, 2020
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable, net	$	78,336	$	82,867	$	77,552	$	84,579
Note receivable, net	9,641		10,000		18,729		19,372
Total	$	87,977	$	92,867	$	96,281	$	103,951

Mortgage notes payable, net	$	3,267,914	$	3,395,569	$	2,909,081	$	3,144,150
Unsecured senior notes, net	9,483,695		9,966,591		9,639,287		10,620,527
Unsecured line of credit	145,000		145,317		—		—
Unsecured term loan, net	—		—		499,390		500,326
Total	$	12,896,609	$	13,507,477	$	13,047,758	$	14,265,003

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

Non-Recurring Fair Value Measurements

During the year ended December 31, 2019, the Company recognized an impairment loss totaling approximately $24.0 million for Boston Properties, Inc. and approximately $22.3 million for Boston Properties Limited Partnership. The Company’s estimated fair value, is considered Level 3 in accordance with ASC 820, and was based on a pending offer form a third party to acquire the property and the subsequent execution of a purchase and sale agreement.

Derivative Instruments and Hedging Activities

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

During the year ended December 31, 2020, the Company elected to apply hedge accounting expedients related to probability and the assessments of effectiveness for future LIBOR-indexed cash flows to assume that the

index upon which future hedged transactions will be based matches the index on the corresponding derivatives. The Company’s application of this expedient preserves the presentation of derivatives consistent with past presentation.

Stock-Based Employee Compensation Plans

At December 31, 2021, the Company had a stock-based employee compensation plan. The Company accounts for the plan under the guidance in ASC 718 “Compensation – Stock Compensation” (“ASC 718”), which revised the fair value based method of accounting for share-based payment liabilities, forfeitures and modifications of stock-based awards and clarified previous guidance in several areas, including measuring fair value, classifying an award as equity or as a liability and attributing compensation cost to reporting periods.

Reclassification

Certain prior year amounts have been reclassified to conform to the current year presentation.

Use of Estimates in the Preparation of Financial Statements

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

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 COVID-19, 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.

Boston Properties, Inc.

Equity Offering Costs

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

Treasury Stock

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

Dividends

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

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


	For the year ended December 31,
	2021					2020					2019
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	2.90		73.86	%	$	2.52		64.91	%	$	2.99		94.84	%
Capital gain income	0.57			14.57	%	0.99			25.49	%	0.16			5.16	%
Return of capital	0.45			11.57	%	0.37			9.60	%	—			—	%
Total	$	3.92	(1)	100.00	%	$	3.88	(2)	100.00	%	$	3.15	(3)	100.00	%

_____________

(1)The fourth quarter 2021 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2022.

(2)The fourth quarter 2020 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2021.

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

Income Taxes

Boston Properties, Inc. has elected to be treated as a REIT under Sections 856 through 860 of the Code, commencing with its taxable year ended December 31, 1997. As a result, it generally will not be subject to federal corporate income tax on its taxable income that is distributed to its stockholders. A REIT is subject to a number of organizational and operational requirements, including a requirement that it currently distribute at least 90% of its annual taxable income (with certain adjustments). Boston Properties, Inc.’s policy is to distribute at least 100% of its taxable income. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to Boston Properties, Inc.’s consolidated taxable REIT subsidiaries. Boston Properties, Inc.’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. Boston Properties, Inc. has no uncertain tax positions recognized as of December 31, 2021 and 2020. At December 31, 2021, Boston Properties, Inc.’s tax returns for the years 2018 forward remain subject to examination by the major tax jurisdictions under the statute of limitations.

The Company owns a hotel property that it leases to one of its taxable REIT subsidiaries and that is managed by Marriott International, Inc. The hotel taxable REIT subsidiary, a wholly owned subsidiary of Boston Properties Limited Partnership, is the lessee pursuant to the lease for the hotel property. As lessor, Boston Properties Limited Partnership is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of a management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, Boston Properties, Inc. has recorded a tax provision in its Consolidated Statements of Operations for the years ended December 31, 2021, 2020 and 2019.

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

Boston Properties Limited Partnership

Income Taxes

The partners are required to report their respective share of Boston Properties Limited Partnership’s taxable income or loss on their respective tax returns and are liable for any related taxes thereon. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to Boston Properties Limited Partnership’s consolidated taxable REIT subsidiaries. Boston Properties Limited Partnership’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. Boston Properties Limited Partnership has no uncertain tax positions recognized as of December 31, 2021 and 2020. At December 31, 2021, Boston Properties Limited Partnership’s tax returns for the years 2018 forward remain subject to examination by the major tax jurisdictions under the statute of limitations.

The Company owns a hotel property which is managed through a taxable REIT subsidiary. The hotel taxable REIT subsidiary, a wholly owned subsidiary Boston Properties Limited Partnership, is the lessee pursuant to the lease for the hotel property. As lessor, Boston Properties Limited Partnership is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of a management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, Boston Properties Limited Partnership has recorded a tax provision in its Consolidated Statements of Operations for the years ended December 31, 2021, 2020 and 2019.

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

Real Estate

12 Months Ended

Dec. 31, 2021

Real Estate [Abstract]

Real Estate

3. Real Estate

Boston Properties, Inc.

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


	December 31, 2021		December 31, 2020
Land	$	5,061,169	$	5,069,206
Right of use assets - finance leases	237,507		237,393
Right of use assets - operating leases (1)	169,778		146,406
Land held for future development (2)	560,355		450,954
Buildings and improvements	14,291,214		13,777,691
Tenant improvements	2,894,025		2,752,880
Furniture, fixtures and equipment	51,695		49,606
Construction in progress	894,172		868,773
Total	24,159,915		23,352,909
Less: Accumulated depreciation	(5,883,961)		(5,534,102)
	$	18,275,954	$	17,818,807

_______________

(1)See Note 4.

(2)Includes pre-development costs.

Boston Properties Limited Partnership

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


	December 31, 2021		December 31, 2020
Land	$	4,964,986	$	4,971,990
Right of use assets - finance leases	237,507		237,393
Right of use assets - operating leases (1)	169,778		146,406
Land held for future development (2)	560,355		450,954
Buildings and improvements	14,014,010		13,498,098
Tenant improvements	2,894,025		2,752,880
Furniture, fixtures and equipment	51,695		49,606
Construction in progress	894,172		868,773
Total	23,786,528		22,976,100
Less: Accumulated depreciation	(5,772,018)		(5,428,576)
	$	18,014,510	$	17,547,524

_______________

(1)See Note 4.

(2)Includes pre-development costs.

Acquisitions

On June 2, 2021, the Company acquired 153 & 211 Second Avenue located in Waltham, Massachusetts for an aggregate purchase price of approximately $100.2 million in cash. 153 & 211 Second Avenue consists of two life sciences lab buildings totaling approximately 137,000 net rentable square feet. The properties are 100% leased. The following table summarizes the allocation of the purchase price, including transaction costs, of 153 & 211 Second Avenue at the date of acquisition (in thousands):


Land	$	33,233
Building and improvements	53,309
Tenant improvements	2,631
In-place lease intangibles	13,415
Below-market lease intangibles	(2,412)
Net assets acquired	$	100,176

On August 2, 2021, the Company acquired Shady Grove Innovation District in Rockville, Maryland, for a purchase price, including transaction costs, of approximately $118.5 million in cash. Shady Grove Innovation District is an approximately 435,000 net rentable square foot, seven-building office park situated on an approximately 31-acre site. The Company intends to reposition three of the buildings, which are currently vacant, to support lab or life sciences uses. As a result, the three vacant buildings are not part of the Company’s in-service portfolio. The Company anticipates that it will redevelop or convert the remaining four buildings to lab or life sciences-related uses as each becomes vacant. The following table summarizes the allocation of the purchase price, including transaction costs, of Shady Grove Innovation District at the date of acquisition (in thousands):


Land	$	52,030
Building and improvements	63,060
Tenant improvements	1,152
In-place lease intangibles	2,523
Above-market lease intangibles	142
Below-market lease intangibles	(403)
Net assets acquired	$	118,504

On December 14, 2021, the Company completed the acquisition of 360 Park Avenue South, an approximately 450,000 square-foot, 20-story Class A office property located in the Midtown South submarket of Manhattan. The gross purchase price, including transaction costs, was approximately $300.7 million and consisted of (1) the assumption of approximately $200.3 million of mortgage debt collateralized by the property and (2) the issuance of approximately 866,503 common units of limited partnership interest in Boston Properties Limited Partnership (“OP Units”). The OP Units issued totaled approximately $99.7 million based on the average closing price per share of BXP common stock for the five trading days immediately preceding the closing date and is recorded as Partners’ Capital in Boston Properties Limited Partnership’s Consolidated Balance Sheets. Following the acquisition, on December 14, 2021, the Company refinanced the mortgage loan with a new lender. The new mortgage loan totals $220.0 million (See Note 7). On December 15, 2021, the Company entered into a joint venture with two institutional partners, as part of the Company’s Strategic Capital Program, and contributed the property and related loan for its aggregate (direct and indirect) 42.21% ownership interest in the joint venture (See Note 6). There was no gain on sale of real estate associated with the contribution of the property to the joint venture. 360 Park Avenue South did not contribute any income to the Company for the period from December 14, 2021 to December 15, 2021. The joint venture has commenced redevelopment activity. The following table summarizes the allocation of the purchase price of 360 Park Avenue South at the date of acquisition (in thousands):


Land	$	215,448
Building and improvements	85,220




Net assets acquired	$	300,668

The following table summarizes the estimated amortization of the acquired in-place lease intangibles

and the acquired above/below-market lease intangibles as of December 31, 2021 for 153 & 211 Second Avenue and Shady Grove Innovation District through the last lease expiration (in thousands):


	Acquired In-Place Lease Intangibles		Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2022	$	9,691	$	74	$	1,713
2023	151		25		39
2024	56		12		26

153 & 211 Second Avenue contributed approximately $5.5 million of revenue and approximately ($2.1) million of earnings to the Company for the period from June 2, 2021 through December 31, 2021. Shady Grove Innovation District contributed approximately $1.2 million of revenue and approximately $(1.5) million of earnings to the Company for the period from August 2, 2021 through December 31, 2021.

Pending Acquisition

On April 19, 2021, the Company entered into an agreement to acquire 11251 Roger Bacon Drive, in Reston, Virginia, for an aggregate purchase price of approximately $5.6 million. The closing is scheduled to occur in the first or second quarter of 2022. 11251 Roger Bacon Drive is an approximately 65,000 square foot office building situated on approximately 2.6 acres. The property is 100% leased to a single tenant with a lease that expires concurrently with the planned closing. There can be no assurance that this transaction will be consummated on the terms currently contemplated or at all.

Developments

On February 1, 2021, the consolidated entity in which the Company has a 55% interest 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 View Boston Observatory at The Prudential Center, a 59,000 net rentable square foot redevelopment of the top three floors of 800 Boylston Street - The Prudential Center, located in Boston, Massachusetts.

On April 16, 2021, the Company removed 3625-3635 Peterson Way from its in-service portfolio following the lease expiration of the last tenant on April 15, 2021. Subsequently, the Company demolished the building and expects to redevelop the site at a future date. 3625-3635 Peterson Way was an approximately 218,000 net rentable square foot Class A office building located in Santa Clara, California.

On October 19, 2021, the Company partially placed in-service Reston Next, a Class A office project with approximately 1.1 million net rentable square feet located in Reston, Virginia.

On December 3, 2021, the Company completed and fully placed in-service approximately 138,000 net rentable square feet at 200 West Street located in Waltham, Massachusetts, a redevelopment to convert a portion of the building to laboratory space.

On December 8, 2021, the Company commenced the development of 103 CityPoint, located in Waltham, Massachusetts. When completed, the building will consist of approximately 113,000 net rentable square feet of life sciences space.

Dispositions

On December 13, 2018, the Company sold its 6595 Springfield Center Drive development project located in Springfield, Virginia. Concurrently with the sale, the Company agreed to act as development manager and guaranteed the completion of the project (See Note 10). The development project achieved final completion during the third quarter of 2021. The total cost of development was determined to be below the estimated total investment at the time of sale. As a result, the Company recognized a gain on sale of real estate of approximately $8.1 million during the year ended December 31, 2021.

On October 25, 2021, the Company completed the sale of its 181,191 and 201 Spring Street properties located in Lexington, Massachusetts for an aggregate gross sales price of $191.5 million. Net cash proceeds totaled approximately $179.9 million, resulting in a gain on sale of real estate totaling approximately $115.6 million for Boston Properties, Inc. and approximately $117.1 million for Boston Properties Limited Partnership. 181,191 and 201 Spring Street are three Class A office properties aggregating approximately 333,000 net rentable square

feet. 181,191 and 201 Spring Street contributed approximately $5.7 million of net income to the Company for the period from January 1, 2021 through October 24, 2021 and contributed approximately $7.2 million and $7.0 million of net income to the Company for the years ended December 31, 2020 and 2019, respectively.

Leases

12 Months Ended

Dec. 31, 2021

Leases [Abstract]

Leases of Lessor Disclosure [Text Block]

4. Leases

In April 2020, the FASB staff issued a question and answer document (“Lease Modification Q & A”) related to the application of lease accounting guidance for lease concessions, in accordance with ASC 842, as a result of COVID-19. The Company did not utilize the guidance provided in the Lease Modification Q & A and instead elected to continue to account for the COVID-19 lease concessions on a lease-by-lease basis in accordance with the existing lease modification accounting framework.

Lessor

The following table summarizes the components of lease revenue recognized during the years ended December 31, 2021, 2020 and 2019 included within the Company's Consolidated Statements of Operations (in thousands):


	Year ended December 31,
Lease Revenue	2021		2020		2019
Fixed contractual payments	$	2,319,362	$	2,211,915	$	2,261,260
Variable lease payments	433,652		434,346		496,754
	$	2,753,014	$	2,646,261	$	2,758,014

The future contractual lease payments to be received (excluding operating expense reimbursements and percentage rent) by the Company as of December 31, 2021, under non-cancelable operating leases which expire on various dates through 2049 (in thousands):


Years Ending December 31,
2022	$	2,252,034
2023	2,251,287
2024	2,138,772
2025	2,012,975
2026	1,877,563
Thereafter	12,215,114

No single tenant represented more than 10.0% of the Company’s total lease revenue for the years ended December 31, 2021, 2020 and 2019.

Lessee, Operating Leases

Lessee

The Company has four non-cancelable ground lease obligations, as lessee, which were classified as operating leases, with various initial term expiration dates through 2114 for the years ended December 31, 2021, 2020 and 2019. The Company recognizes ground rent expense on a straight-line basis over the term of the respective ground lease agreements. As of December 31, 2021, none of the amounts disclosed below for these ground leases contain variable payments, extension options or residual value guarantees.

The Company has four finance lease obligations with various initial term expiration dates through 2094 for the years ended December 31, 2021, 2020 and 2019.

The following table provides lease cost information for the Company’s operating and finance leases for the years ended December 31, 2021, 2020 and 2019 (in thousands):


	Year ended December 31,
Lease costs	2021		2020		2019
Operating lease costs	$	13,151	$	13,948	$	14,573
Finance lease costs
Amortization of right of use asset (1)	$	547	$	56	$	29
Interest on lease liabilities (2)	$	2,471	$	583	$	47

_______________

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

(2)Two, three and three of the finance leases relate to assets under development for all or a portion of the years ended December 31, 2021, December 31, 2020 and December 31, 2019, respectively, and as such, a portion of the interest amount was capitalized.

The following table provides other quantitative information for the Company’s operating and finance leases as of December 31, 2021 and December 31, 2020:


	December 31, 2021		December 31, 2020
Other information
Weighted-average remaining lease term (in years)
Operating leases	50		51
Finance leases	69		70
Weighted-average discount rate
Operating leases	5.7	%	5.7	%
Finance leases	6.2	%	6.2	%

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2021 (in thousands):


	Operating		Finance
2022	$	19,623	$	8,762
2023	25,333		10,826
2024 (1)	10,085		48,605
2025	10,307		9,971
2026	10,100		10,166
Thereafter	538,801		1,363,011
Total lease payments	614,249		1,451,341
Less: Interest portion	(409,688)		(1,206,920)
Present value of lease payments	$	204,561	$	244,421

_______________

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

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2020 (in thousands):


	Operating		Finance
2021	$	25,092	$	5,896
2022	18,020		10,206
2023	10,262		9,701
2024 (1)	9,277		48,518
2025	9,476		9,971
Thereafter	548,478		1,373,177
Total lease payments	620,605		1,457,469
Less: Interest portion	(418,892)		(1,220,977)
Present value of lease payments	$	201,713	$	236,492

_______________

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

Ground Lease

On May 19, 2021, the Company amended its ground lease at Sumner Square in Washington, DC to extend the term for an additional 15 years. Prior to the amendment, the ground lease was scheduled to expire on August 10, 2066. The ground lease will now expire on August 9, 2081. The amended lease required the Company to pay $23.0 million of rent in 2021 and requires the Company’s remaining obligation of approximately $4.0 million be used to fund certain operation and maintenance costs incurred by the government with respect to the Sumner School for the next five years, with no payments thereafter. The Company’s incremental borrowing rate is 3.95% per annum. The net present value of the total ground lease payments is approximately $26.7 million. The Company continues

to classify this ground lease as an operating lease. As a result, the Company recorded a Right-of-Use Assets - Operating Leases and Lease Liabilities - Operating Leases of approximately $27.1 million and $26.7 million, respectively, on its Consolidated Balance Sheet. On July 1, 2021, the Company made the $23.0 million payment. As of December 31, 2021, the lease liability within Lease Liabilities - Operating Leases on the Consolidated Balance Sheets is approximately $3.4 million. The Sumner Square ground lease had operating lease costs of approximately $0.7 million, $1.4 million and $1.5 million during the years ended December 31, 2021, 2020 and 2019, respectively. Sumner Square is an approximately 210,000 net rentable square foot Class A office building.

The following table provides a maturity analysis for the Company’s lease liabilities related to its Sumner Square operating lease as of May 19, 2021 (in thousands):


	Operating
Period from May 19, 2021 through December 31, 2021	$	23,599
2022	761
2023	784
2024	808
2025	832
2026	422
Total lease payments	27,206
Less: Interest portion	(536)
Present value of lease payments	$	26,670

Deferred Charges

12 Months Ended

Dec. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Deferred Charges

5. Deferred Charges

Deferred charges consisted of the following at December 31, 2021 and 2020 (in thousands):


	December 31, 2021		December 31, 2020
Leasing costs, including lease related intangibles	$	1,011,229	$	1,023,058
Financing costs	19,231		12,728
	1,030,460		1,035,786
Less: Accumulated amortization	(411,662)		(395,701)
	$	618,798	$	640,085

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


	Acquired In-Place Lease Intangibles
2022	$	13,827
2023	3,911
2024	2,200
2025	2,112
2026	1,624

Investments in Unconsolidated Joint Ventures

12 Months Ended

Dec. 31, 2021

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures

6. Investments in Unconsolidated Joint Ventures

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


					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			December 31, 2021		December 31, 2020
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.00	%		$	(1,205)	$	(3,766)
BP/CRF Metropolitan Square LLC	Metropolitan Square	20.00	%		(15,356)		(13,584)
901 New York, LLC	901 New York Avenue	25.00	%	(2)	(12,597)		(12,264)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.33	%	(3)	33,732		35,297
Annapolis Junction NFM LLC	Annapolis Junction	50.00	%	(4)	N/A		13,463
540 Madison Venture LLC	540 Madison Avenue	60.00	%	(5)	N/A		122
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.00	%		(7,913)		(6,945)
501 K Street LLC	1001 6th Street	50.00	%	(6)	42,576		42,499
Podium Developer LLC	The Hub on Causeway - Podium	50.00	%		48,980		48,818
Residential Tower Developer LLC	Hub50House	50.00	%		47,774		50,943
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.00	%		11,505		10,754
Office Tower Developer LLC	100 Causeway Street	50.00	%		57,687		56,312
1265 Main Office JV LLC	1265 Main Street	50.00	%		3,541		3,787
BNY Tower Holdings LLC	Dock 72	50.00	%		27,343		29,536
BNYTA Amenity Operator LLC	Dock 72	50.00	%		1,069		1,846
CA-Colorado Center Limited Partnership	Colorado Center	50.00	%		231,479		227,671
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.00	%		61,626		58,112
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.00	%		116,306		113,774
SMBP Venture LP	Santa Monica Business Park	55.00	%		156,639		145,761
Platform 16 Holdings LP	Platform 16	55.00	%	(7)	109,086		108,393
Gateway Portfolio Holdings LLC	Gateway Commons	50.00	%	(8)	327,148		336,206
Rosecrans-Sepulveda Partners 4, LLC	Beach Cities Media Campus	50.00	%		27,106		27,184
Safeco Plaza REIT LLC	Safeco Plaza	33.67	%	(9)	72,545		N/A
360 PAS Holdco LLC	360 Park Avenue South	42.21	%	(10)	106,855		N/A
					$	1,445,926	$	1,273,919

_______________

(1)Investments with deficit balances aggregating approximately $37.1 million and $36.6 million at December 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 December 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 33.33% 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 December 31, 2021 and the joint venture has been dissolved.

(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 50% and 55% interest in the joint venture at December 31, 2021 and December 31, 2020, respectively.

(9)The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities (each, a “Safeco Partner Entity”) through which each partner owns its interest in the joint venture.

(10)The Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the two entities (each, a “360 Park Avenue South Partner Entity”) through which each partner owns its interest in the joint venture.

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. Under certain of the Company’s joint venture agreements, if certain return thresholds are achieved, the partners or the Company will be entitled to an additional promoted interest or payments.

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


	December 31, 2021		December 31, 2020
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	5,579,218	$	4,708,571
Other assets	586,470		531,071
Total assets	$	6,165,688	$	5,239,642
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	3,214,961	$	2,637,911
Other liabilities (2)	652,135		650,433
Members’/Partners’ equity	2,298,592		1,951,298
Total liabilities and members’/partners’ equity	$	6,165,688	$	5,239,642
Company’s share of equity	$	1,104,175	$	936,087
Basis differentials (3)	341,751		337,832
Carrying value of the Company’s investments in unconsolidated joint ventures (4)	$	1,445,926	$	1,273,919

_______________

(1)At December 31, 2021 and December 31, 2020, this amount included right of use assets - finance leases totaling approximately $248.9 million. At December 31, 2021 and December 31, 2020, this amount included right of use assets - operating leases totaling approximately $22.3 million and $22.5 million, respectively.

(2)At December 31, 2021 and December 31, 2020, this amount included lease liabilities - finance leases totaling approximately $385.5 million and $388.7 million, respectively, and lease liabilities - operating leases totaling approximately $30.4 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 majority of the Company’s basis differences are as follows:


	December 31, 2021		December 31, 2020
Property	(in thousands)
Colorado Center	$	304,776	$	307,328
Gateway Commons	51,009		51,875
Dock 72	(50,051)		(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 $37.1 million and $36.6 million at December 31, 2021 and 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:


	Year ended December 31,
		2021		2020		2019
		(in thousands)
Total revenue (1)		$	383,649	$	319,560	$	322,817
Expenses
Operating		158,498		144,347		122,992
Transaction costs		470		1,027		1,000
Depreciation and amortization		147,121		141,853		102,296
Total expenses		306,089		287,227		226,288
Other income (expense)
Interest expense		(108,884)		(98,051)		(84,409)
Gains on sales of real estate (2)		—		11,737		32,706
Net income (loss)		$	(31,324)	$	(53,981)	$	44,826

Company’s share of net income (loss)		$	(10,254)	$	(16,256)	$	24,423
Gain on sale of investment (3)		10,257		—		—
Impairment loss on investment (4)		—		(60,524)		—
Basis differential (2)(4)(5)		(2,573)		(8,330)		22,169
Income (loss) from unconsolidated joint ventures		$	(2,570)	$	(85,110)	$	46,592

_______________

(1)Includes straight-line rent adjustments of approximately $17.2 million, $(10.1) million and $32.4 million for the years ended December 31, 2021, 2020 and 2019, respectively.

(2)For the year ended December 31, 2020, represents the gain on sale of Annapolis Junction Building Eight and two land parcels. For the year ended December 31, 2019, represents the gain on sale of 540 Madison Avenue recognized by the joint venture. During 2008, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture resulting in a basis differential between the carrying value of the Company’s investment in the joint venture and the joint venture’s basis in the assets and liabilities of the property. As a result of the historical basis difference, the Company recognized a gain on sale of real estate totaling approximately $47.2 million for the year ended December 31, 2019, which consists of its share of the gain on sale reported by the joint venture as well as an adjustment for the basis differential. The gain on sale of real estate is included in Income (loss) from Unconsolidated Joint Ventures in the Company’s Consolidated Statements of Operations.

(3)During the year ended December 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.

(4)During the year ended December 31, 2020, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $60.5 million.

(5)Includes straight-line rent adjustments of approximately $0.8 million, $1.8 million and $2.1 million for the years ended December 31, 2021, 2020 and 2019, respectively. Also includes net above-/below-market rent adjustments of approximately $0.4 million, $0.9 million and $1.7 million for the years ended December 31, 2021, 2020 and 2019, respectively.

On February 25, 2021, a joint venture in which the Company had a 54% interest commenced the development of 751 Gateway, a laboratory building located in South San Francisco, California, that is expected to be approximately 231,000 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 December 31, 2021, the Company had a 50% interest in the joint venture. In accordance with the terms of the joint venture agreement, the Company expects it will have a 49% interest in this property.

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 $17.8 million after repayment of the

Company's share of debt totaling approximately $15.1 million. 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 received a distribution of approximately $5.8 million of available cash. 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.

On June 11, 2021, a joint venture in which the Company has a 50% interest partially placed in-service 100 Causeway Street, a Class A office project with approximately 634,000 net rentable square feet located in Boston, Massachusetts. On December 1, 2021, the property was fully placed in service.

On August 31, 2021, a joint venture in which the Company has a 50% interest extended the construction loan collateralized by its The Hub on Causeway – Podium property. At the time of the extension, the outstanding balance of the loan totaled approximately $174.3 million, bore interest at a variable rate equal to LIBOR plus 2.25% per annum and was scheduled to mature on September 6, 2021, with two, one-year extension options, subject to certain conditions. The extended loan continues to bear interest at a variable rate equal to LIBOR plus 2.25% per annum and matures on September 6, 2023. The Hub on Causeway – Podium is a retail and office property with approximately 382,000 net rentable square feet located in Boston, Massachusetts.

On September 1, 2021, the Company entered into a joint venture to acquire Safeco Plaza, a Class A office property located in Seattle, Washington, for a net purchase price of approximately $460.1 million, including $4.9 million of seller-funded leasing and capital costs. Safeco Plaza is a 50-story, approximately 765,000 net rentable square-foot, Class A office property. The acquisition was completed through a newly formed joint venture with two institutional partners. Each of the institutional partners invested approximately $71.9 million of cash for their respective 33.165% ownership interest in the joint venture. The Company invested approximately $72.6 million for their 33.67% interest in the joint venture and is providing customary operating, property management and leasing services to the joint venture. The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities (each a “Safeco Partner Entity”) through which each partner owns its interest in the joint venture. Subject to the occurrence of certain events and the joint venture achieving certain return thresholds, the Company is entitled to earn promote distributions. Some of the promote distributions may be payable in cash or, at the Company’s election, additional equity interest(s) in the Safeco Partner Entity(ies). The purchase price was funded with cash and proceeds from a new mortgage loan collateralized by the property. The mortgage loan has a principal amount of $250.0 million, bears interest at a variable rate equal to the greater of (x) 2.35% or (y) LIBOR plus 2.20% per annum and matures on September 1, 2026. The following table summarizes the allocation of the purchase price, including transaction costs, of Safeco Plaza joint venture at the date of acquisition (in thousands):


Land	$	81,343
Building and improvements	351,948
Tenant improvements	30,404
In-place lease intangibles	28,658
Above-market lease intangibles	301
Below-market lease intangibles	(32,542)
Net assets acquired	$	460,112

The following table summarizes the estimated amortization of the acquired in-place lease intangibles and the acquired above/below-market lease intangibles as of December 31, 2021, for Safeco Plaza for each of the next five succeeding fiscal years (in thousands):


	Acquired In-Place Lease Intangibles		Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2022	$	4,278	$	49	$	4,663
2023	3,453		49		4,596
2024	3,036		49		4,383
2025	2,851		49		4,337
2026	2,749		42		4,329

On October 29, 2021, a joint venture in which the Company has a 50% interest completed and fully placed in-service 7750 Wisconsin Avenue, a Class A office project with approximately 733,000 net rentable square feet located in Bethesda, Maryland.

On December 14, 2021, the Company completed the acquisition of 360 Park Avenue South (See Note 3). On December 15, 2021, the Company entered into a joint venture with two institutional partners to own, operate and redevelop the property. The Company contributed the property and related loan for its aggregate (direct and indirect) 42.21% interest in the joint venture. The joint venture has commenced redevelopment activity, including modernizing building systems and creating amenities, collaborative spaces, and client spaces. The Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the “360 Park Avenue South Partner Entity through which each partner owns its interest in the joint venture. The Company’s partners will fund required capital until their aggregate investment is approximately 58% of all capital contributions; thereafter, the partners will fund required capital according to their percentage interests. Subject to the occurrence of certain events and the joint venture achieving certain return thresholds, the Company is entitled to earn promote distributions. Some of the promote distributions may be payable in cash or, at the Company’s election, additional equity interest(s) in the 360 Park Avenue South Partner Entity(ies). The mortgage loan has a principal amount of $220.0 million, of which $202.0 million was advanced at closing, bears interest at a variable rate equal to the Adjusted Term SOFR plus 2.40% and matures on December 14, 2024, with two one-year extension options, subject to certain conditions. The spread on the variable rate may be reduced, subject to certain conditions.

Mortgage Notes Payable, Net

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Mortgage Notes Payable Disclosure

7. Mortgage Notes Payable

The Company had outstanding mortgage notes payable totaling approximately $3.3 billion and $2.9 billion as of December 31, 2021 and 2020, respectively, each collateralized by one or more buildings and related land included in real estate assets. The mortgage notes payable are generally due in monthly installments and mature at various dates through January 9, 2032.

Fixed rate mortgage notes payable totaled approximately $3.3 billion and $2.9 billion at December 31, 2021 and 2020, respectively, with contractual interest rates ranging from 2.79% to 3.43% per annum at December 31, 2021 and 3.43% to 6.94% per annum at December 31, 2020 (with a weighted-average interest rate of 3.24% and 3.72% per annum at December 31, 2021 and 2020, respectively). There were no variable rate mortgage loans at December 31, 2021 and 2020.

On 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.

On December 10, 2021, the consolidated entity in which the Company has a 55% interest refinanced the mortgage loan collateralized by its 601 Lexington Avenue property located in New York City with a new lender. The mortgage loan has a principal amount of $1.0 billion, requires interest-only payments at a fixed interest rate of 2.79% per annum and matures on January 9, 2032. The previous mortgage loan had an outstanding balance of approximately $616.1 million, bore interest at a fixed rate of 4.75% per annum and was scheduled to mature on April 10, 2022. There was no prepayment penalty associated with the repayment of the previous mortgage loan. The Company recognized a loss from early extinguishment of debt totaling approximately $0.1 million due to the write-off of unamortized deferred financing costs.

On December 14, 2021, the Company completed the acquisition of 360 Park Avenue South, located in the Midtown South submarket of Manhattan. The gross purchase price, including transaction costs, was approximately

$300.7 million and consisted of (1) the assumption of approximately $200.3 million of mortgage debt collateralized by the property and (2) the issuance of approximately 866,503 OP Units (See Note 3). Following the acquisition, on December 14, 2021, the Company refinanced the mortgage loan with a new lender. The new mortgage loan totaling $220.0 million, of which $202.0 million was advanced at closing, bears interest at a variable rate equal to the Adjusted Term SOFR plus 2.40% per annum and matures on December 14, 2024 with two, one-year extension options, subject to certain conditions. The spread on the variable rate may be reduced, subject to certain conditions. The loan proceeds were used to prepay the previous mortgage loan, which had an outstanding principal balance of approximately $200.3 million, bore interest at a fixed rate of 6.044% per annum and was scheduled to mature on March 1, 2022. There was no prepayment penalty associated with the repayment of the mortgage loan. On December 15, 2021, the Company entered into a joint venture with two institutional partners, as part of the Company’s Strategic Capital Program, and contributed the property and related loan for its aggregate (direct and indirect) 42.21% ownership interest in the joint venture (See Note 6).

Contractual aggregate principal payments of mortgage notes payable at December 31, 2021 are as follows (in thousands):


	Principal Payments
2022	$	—
2023	—
2024	—
2025	—
2026	—
Thereafter	3,300,000
Total aggregate principal payments	3,300,000
Deferred financing costs, net	(32,086)
Total carrying value of mortgage notes payable, net	$	3,267,914

Unsecured Senior Notes

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Unsecured Senior Notes

8. Unsecured Senior Notes

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


	Coupon/Stated Rate		Effective Rate(1)		Principal Amount		Maturity Date(2)
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
12 Year Unsecured Senior Notes	2.450	%	2.524	%	850,000		October 1, 2033
Total principal					9,550,000
Less:
Net unamortized discount					16,548
Deferred financing costs, net					49,757
Total					$	9,483,695

_______________

(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 the stated principal 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.

On September 29, 2021, Boston Properties Limited Partnership completed a public offering of $850.0 million in aggregate principal amount of its 2.450% unsecured senior notes due 2033. The notes were priced at 99.959% of the principal amount to yield an effective rate (including financing fees) of approximately 2.524% per annum to maturity. The notes will mature on October 1, 2033, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $842.5 million after deducting underwriting discounts and transaction expenses.

On October 15, 2021, Boston Properties Limited Partnership used proceeds from its September 2021 offering of unsecured senior notes and borrowings under its credit facility entered into in June 2021 (as amended and restated, the “2021 Credit Facility”) to complete the redemption of $1.0 billion in aggregate principal amount of its 3.85% senior notes due February 1, 2023. The redemption price was approximately $1.05 billion. The redemption price included approximately $7.9 million of accrued and unpaid interest to, but not including, the redemption date. Excluding the accrued and unpaid interest, the redemption price was approximately 104.284% of the principal amount being redeemed. The Company recognized a loss from early extinguishment of debt totaling approximately $44.2 million, which amount included the payment of the redemption premium totaling approximately $42.8 million.

The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60%, (2) a secured debt leverage ratio not to exceed 50%, (3) an interest coverage ratio of greater than 1.50, and (4) an unencumbered asset value of not less than 150% of unsecured debt. At December 31, 2021, Boston Properties Limited Partnership was in compliance with each of these financial restrictions and requirements.

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

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Stockholders' Equity / Partners' Capital

Unsecured Credit Facility	12 Months Ended
Unsecured Credit Facility	Dec. 31, 2021
Line of Credit Facility [Abstract]
Unsecured Credit Facility	9. Unsecured Credit Facility On March 16, 2021, Boston Properties Limited Partnership repaid $500.0 million, representing all amounts outstanding on its delayed draw term loan facility under its unsecured revolving credit agreement (the “2017 Credit Facility”). The Company recognized a loss from early extinguishment of debt totaling approximately $0.5 million related to unamortized financing costs. On June 15, 2021, Boston Properties Limited Partnership amended and restated the 2017 Credit Facility and entered into the 2021 Credit Facility. The 2021 Credit Facility provides for borrowings of up to $1.5 billion (the “Revolving Facility”), subject to customary conditions. Among other things, the amendment and restatement (1) extended the maturity date to June 15, 2026, (2) eliminated the $500.0 million delayed draw term loan facility provided under the 2017 Credit Facility, (3) reduced the per annum variable interest rates on borrowings and (4) added a sustainability-linked pricing component. Under the 2021 Credit Facility, Boston Properties Limited Partnership may increase the total commitment by up to $500.0 million by increasing the amount of the Revolving Facility and/or by incurring one or more term loans, in each case, subject to syndication of the increase and other conditions. The 2021 Credit Facility replaces the 2017 Credit Facility, which was scheduled to expire on April 24, 2022. At Boston Properties Limited Partnership’s option, loans under the 2021 Credit Facility will bear interest at a rate per annum equal to (1) (a) in the case of loans denominated in Dollars, LIBOR, (b) in the case of loans denominated in Euro, EURIBOR, (c) in the case of loans denominated in Canadian Dollars, CDOR, and (d) in the case of loans denominated in Sterling, SONIA, in each case, plus a margin ranging from 70.0 to 140.0 basis points based on Boston Properties Limited Partnership’s credit rating or (2) an alternate base rate equal to the greatest of (a) the Federal Funds rate plus 0.5%, (b) the Administrative Agent’s prime rate, (c) LIBOR for a one-month period plus 1.00%, and (d) 1.00%, in each case, plus a margin ranging from 0 to 40 basis points based on Boston Properties Limited Partnership’s credit rating. The 2021 Credit Facility also features a sustainability-linked pricing component such that if Boston Properties Limited Partnership meets certain sustainability performance targets, the applicable per annum interest rate will be reduced by one basis point. The LIBOR replacement provisions in the 2021 Credit Facility permit the use of rates based on the secured overnight financing rate administered by the Federal Reserve Bank of New York plus an applicable spread adjustment. In addition, the 2021 Credit Facility contains a competitive bid option for up to 65% of the Revolving Facility that allows banks that are part of the lender consortium to bid to make loan advances to Boston Properties Limited Partnership at a reduced interest rate. Pursuant to the 2021 Credit Facility, Boston Properties Limited Partnership is obligated to pay (1) in quarterly installments a facility fee on the total commitment under the Revolving Facility at a rate per annum ranging from 0.10% to 0.30% based on Boston Properties Limited Partnership’s credit rating and (2) an annual fee on the undrawn amount of each letter of credit ranging from 0.70% to 1.40% based on Boston Properties Limited Partnership’s credit rating. Based on Boston Properties Limited Partnership’s December 31, 2021 credit rating, (1) the applicable Eurocurrency and LIBOR Daily Floating Rate margins are 0.775%, (2) the alternate base rate margin is zero basis points and (3) the facility fee is 0.15% per annum. At December 31, 2021, Boston Properties Limited Partnership had $145.0 million outstanding under its Revolving Facility. At December 31, 2020, Boston Properties Limited Partnership had no amount outstanding under its Revolving Facility and $500.0 million of borrowings outstanding under its delayed draw term loan facility under its 2017 Credit Facility. The 2021 Credit Facility contains customary representations and warranties, affirmative and negative covenants, and events of default provisions, including the failure to pay indebtedness, breaches of covenants and bankruptcy and other insolvency events, which could result in the acceleration of the obligation to repay all outstanding amounts and the cancellation of all commitments outstanding under the 2021 Credit Facility. Among other covenants, the 2021 Credit Facility requires that Boston Properties Limited Partnership maintain on an ongoing basis: (1) a leverage ratio not to exceed 60%, however, the leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (2) a secured debt leverage ratio not to exceed 55%, (3) a fixed charge coverage ratio of at least 1.40, (4) an unsecured debt leverage ratio not to exceed 60%, however, the unsecured debt leverage ratio may increase to no greater than 65% provided that it is reduced to 60% within one year, (5) an unsecured debt interest coverage ratio of at least 1.75 and (6) limitations on permitted investments. At December 31, 2021, Boston Properties Limited Partnership was in compliance with each of these financial and other covenant requirements.

Commitments And Contingencies	12 Months Ended
Commitments And Contingencies	Dec. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	10. 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 had letter of credit and performance obligations related to lender and development requirements that total approximately $26.4 million at December 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. 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 December 31, 2021, the maximum funding obligation under the guarantee was approximately $19.0 million. The Company earns a fee from the joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee. As of December 31, 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 December 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 was 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. Final completion of the project was achieved during the year ended December 31, 2021 and the Company has been released of its guarantee obligations (See Note 3). 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 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. Concentrations of Credit Risk Management of the Company performs ongoing credit evaluations of tenants and may require tenants to provide some form of credit support such as corporate guarantees and/or other financial guarantees. Although the Company’s properties are geographically diverse and the tenants operate in a variety of industries, to the extent the Company has a significant concentration of rental revenue from any single tenant, the inability of that tenant to make its lease payments could have an adverse effect on the Company. Insurance The Company’s property insurance program per occurrence limits are $1.0 billion for its portfolio insurance program, including coverage for acts of terrorism other than nuclear, biological, chemical or radiological terrorism (“Terrorism Coverage”). The Company also carries $1.35 billion of property insurance in excess of the $1.0 billion of coverage in the Company’s property insurance program for 601 Lexington Avenue, New York, New York, consisting of $750 million of property and Terrorism Coverage in excess of the Company’s property insurance program and $600 million of Terrorism Coverage only in excess of the $1.75 billion of coverage. 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. 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. This insurance is subject to a deductible in the amount of 3% of the value of the affected property. In addition, the Company currently carries earthquake insurance which covers its Seattle region with a $60 million per occurrence limit, and a $60 million annual aggregate limit. This insurance is subject to a deductible in the amount of 2% of the value of the affected property. 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 has provided 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, earthquakes 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. Legal Matters The Company is subject to various legal proceedings and claims that arise in the ordinary course of business. These matters are generally covered by insurance. Management believes that the final outcome of such matters will not have a material adverse effect on the financial position, results of operations or liquidity of the Company. State and Local Tax Matters Because Boston Properties, Inc. is organized and qualifies as a REIT, it is generally not subject to federal income taxes, but is subject to certain state and local taxes. In the normal course of business, certain entities through which the Company owns real estate either have undergone, or are currently undergoing, tax audits. Although the Company believes that it has substantial arguments in favor of its positions in the ongoing audits, in some instances there is no controlling precedent or interpretive guidance on the specific point at issue. Collectively, tax deficiency notices received to date from the jurisdictions conducting the ongoing audits have not been material. However, there can be no assurance that future audits will not occur with increased frequency or that the ultimate result of such audits will not have a material adverse effect on the Company’s results of operations. Environmental Matters It is the Company’s policy to retain independent environmental consultants to conduct or update Phase I environmental assessments (which generally do not involve invasive techniques such as soil or ground water sampling) and asbestos surveys in connection with the Company’s acquisition of properties. These pre-purchase environmental assessments have not revealed environmental conditions that the Company believes will have a material adverse effect on its business, assets, financial condition, results of operations or liquidity, and the Company is not otherwise aware of environmental conditions with respect to its properties that the Company believes would have such a material adverse effect. However, from time to time environmental conditions at the Company’s properties have required and may in the future require environmental testing and/or regulatory filings, as well as remedial action. In February 1999, the Company (through a joint venture) acquired from Exxon Corporation a property in Massachusetts that was formerly used as a petroleum bulk storage and distribution facility and was known by the state regulatory authority to contain soil and groundwater contamination. The Company developed an office park on the property. The Company engaged a specially licensed environmental consultant to oversee the management of contaminated soil and groundwater that was disturbed in the course of construction. Under the property acquisition agreement, Exxon agreed to (1) bear the liability arising from releases or discharges of oil and hazardous substances which occurred at the site prior to the Company’s ownership, (2) continue monitoring and/or remediating such releases and discharges as necessary and appropriate to comply with applicable requirements, and (3) indemnify the Company for certain losses arising from preexisting site conditions. Any indemnity claim may be subject to various defenses and contractual limitations, including time limits, and there can be no assurance that the amounts paid under the indemnity, if any, would be sufficient to cover the liabilities arising from any such releases and discharges. Environmental investigations at some of the Company’s properties and certain properties owned by affiliates of the Company have identified groundwater contamination migrating from off-site source properties. In each case the Company engaged a licensed environmental consultant to perform the necessary investigations and assessments and to prepare any required submittals to the regulatory authorities. In each case the environmental consultant concluded that the properties qualify under the regulatory program or the regulatory practice for a status which eliminates certain deadlines for conducting response actions at a site. The Company also believes that these properties qualify for liability relief under certain statutory provisions or regulatory practices regarding upgradient releases. Although the Company believes that the current or former owners of the upgradient source properties may bear responsibility for some or all of the costs of addressing the identified groundwater contamination, the Company will take such further response actions (if any) that it deems necessary or advisable. Other than periodic testing at some of these properties, no such additional response actions are anticipated at this time. Some of the Company’s properties and certain properties owned by the Company’s affiliates are located in urban, industrial and other previously developed areas where fill or current or historical uses of the areas have caused site contamination. Accordingly, it is sometimes necessary to institute special soil and/or groundwater handling procedures and/or include particular building design features in connection with development, construction and other property operations in order to achieve regulatory closure and/or ensure that contaminated materials are addressed in an appropriate manner. In these situations, it is the Company’s practice to investigate the nature and extent of detected contamination, including potential issues associated with vapor intrusion concerns and/or potential contaminant migration to or from the subject property in ground water, assess potential liability risks and estimate the costs of required response actions and special handling procedures. The Company then uses this information as part of its decision-making process with respect to the acquisition, deal structure and/or development of the property. For example, the Company owns a parcel in Massachusetts which was formerly used as a quarry/asphalt batching facility. Pre-purchase testing indicated that the site contained relatively low levels of certain contaminants. The Company has developed an office park on this property. Prior to and during redevelopment activities, the Company engaged a specially licensed environmental consultant to monitor environmental conditions at the site and prepare necessary regulatory submittals based on the results of an environmental risk characterization. A submittal has been made to the regulatory authorities in order to achieve regulatory closure at this site. The submittal included an environmental deed restriction that mandates compliance with certain protective measures in a portion of the site where low levels of residual soil contamination have been left in place in accordance with applicable laws. The Company expects that resolution of the environmental matters relating to the above will not have a material impact on its business, assets, financial condition, results of operations or liquidity. However, the Company cannot assure you that it has identified all environmental liabilities at its properties, that all necessary remediation actions have been or will be undertaken at the Company’s properties or that the Company will be indemnified, in full or at all or that the Company will have insurance coverage, in the event that such environmental liabilities arise.

Noncontrolling Interests

12 Months Ended

Dec. 31, 2021

Noncontrolling Interest [Abstract]

Noncontrolling Interests

11. Noncontrolling Interests

Noncontrolling interests relate to the interests in Boston Properties Limited Partnership not owned by Boston Properties, Inc. and interests in consolidated property partnerships not wholly-owned by the Company. As of December 31, 2021, the noncontrolling interests in Boston Properties Limited Partnership consisted of 16,561,186 OP Units, 1,485,376 LTIP Units (including 418,974 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 years ended December 31, 2021 and 2020, 523,969 and 856,811 OP Units, respectively, were presented by the holders for redemption (including 148,442 and 88,168 OP Units, respectively, 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 December 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 9, 2019, the measurement period for the Company’s 2016 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 69.5% of target, or an aggregate of approximately $13.6 million (after giving effect to employee separations). As a result, an aggregate of 364,980 2016 MYLTIP Units that had been previously granted were automatically forfeited.

On February 6, 2020, the measurement period for the Company’s 2017 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final awards were determined to be 83.8% of target, or an aggregate of approximately $17.6 million (after giving effect to employee separations). As a result, an aggregate of 270,942 2017 MYLTIP Units that had been previously granted were automatically forfeited.

On February 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.

On December 14, 2021, Boston Properties Limited Partnership issued approximately 866,503 OP Units as partial consideration for the acquisition of 360 Park Avenue South in New York, New York (See Note 3). The OP Units issued totaled approximately $99.7 million based on the average closing price per share of Boston Properties Inc.’s common stock for the five trading days immediately preceding the closing date.

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 year ended December 31, 2021:


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 31, 2021	January 28, 2022	$0.98	$0.098
September 30, 2021	October 29, 2021	$0.98	$0.098
June 30, 2021	July 30, 2021	$0.98	$0.098
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 year ended December 31, 2020:


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 31, 2020	January 28, 2021	$0.98	$0.098
September 30, 2020	October 30, 2020	$0.98	$0.098
June 30, 2020	July 31, 2020	$0.98	$0.098
March 31, 2020	April 30, 2020	$0.98	$0.098
December 31, 2019	January 30, 2020	$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 - 2015 MYLTIP Units and, after the February 9, 2019 measurement date, the 2016 MYLTIP Units) and its distributions on the 2016 MYLTIP Units (prior to the February 9, 2019 measurement date) and 2017 - 2019 MYLTIP Units (after the February 5, 2019 issuance date of the 2019 MYLTIP Units) that occurred during the year ended December 31, 2019:


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

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 December 31, 2021 was approximately $2.1 billion based on the last reported price of a share of Common Stock on the New York Stock Exchange of $115.18 per share on December 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 $1.6 billion and $1.7 billion at December 31, 2021 and December 31, 2020, respectively, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.

Stockholders' Equity / Partners' Capital

12 Months Ended

Dec. 31, 2021

Equity [Abstract]

12. Stockholders’ Equity / Partners’ Capital

Boston Properties, Inc.

As of December 31, 2021, Boston Properties, Inc. had 156,544,849 shares of Common Stock outstanding.

As of December 31, 2021, Boston Properties, Inc. owned 1,745,914 general partnership units and 154,798,935 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 years ended December 31, 2021 and 2020, Boston Properties, Inc. issued 247,920 and 43,792 shares of Common Stock, respectively, upon the exercise of options to purchase Common Stock.

During the years ended December 31, 2021 and 2020, Boston Properties, Inc. issued 523,969 and 856,811 shares of Common Stock, respectively, in connection with the redemption of an equal number of redeemable OP Units from limited partners.

The following table presents Boston Properties, Inc.’s dividends per share and Boston Properties Limited Partnership’s distributions per OP Unit and LTIP Unit paid or declared during the years ended December 31, 2021, 2020 and 2019:


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
December 31, 2021	January 28, 2022	$0.98	$0.98
September 30, 2021	October 29, 2021	$0.98	$0.98
June 30, 2021	July 30, 2021	$0.98	$0.98
March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98
September 30, 2020	October 30, 2020	$0.98	$0.98
June 30, 2020	July 31, 2020	$0.98	$0.98
March 31, 2020	April 30, 2020	$0.98	$0.98
December 31, 2019	January 30, 2020	$0.98	$0.98
September 30, 2019	October 31, 2019	$0.95	$0.95
June 28, 2019	July 31, 2019	$0.95	$0.95
March 29, 2019	April 30, 2019	$0.95	$0.95
December 31, 2018	January 30, 2019	$0.95	$0.95

Preferred Stock

At December 31, 2020, Boston Properties, Inc. had 80,000 shares (8,000,000 Depositary Shares each representing 1/100th of a share) outstanding of its 5.25% Series B Preferred Stock with a liquidation preference of $2,500.00 per share ($25.00 per Depositary Share). Boston Properties, Inc. paid cumulative cash dividends on the Series B Preferred Stock at a rate of 5.25% per annum of the $2,500.00 liquidation preference per share. Boston Properties, Inc. did not have the right to redeem the Series B Preferred Stock prior to March 27, 2018, except in certain circumstances relating to the preservation of Boston Properties, Inc.’s REIT status. On and after March 27, 2018, Boston Properties, Inc., at its option, could redeem the Series B Preferred Stock for a cash redemption price of $2,500.00 per share ($25.00 per Depositary Share), plus all accrued and unpaid dividends. The Series B Preferred Stock was not redeemable by the holders, had no maturity date and was not convertible into any other security of Boston Properties, Inc. or its affiliates.

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. The redemption price per share of Series B Preferred Stock was $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. 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 is 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.

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 and all of the outstanding Depositary Shares. In connection with the redemption of the Series B Preferred Stock, all 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 following table presents Boston Properties, Inc.’s dividends per share on its Series B Preferred Stock paid or declared during the years ended December 31, 2021, 2020 and 2019:

Record Date

Payment Date

Dividend (Per Share)

February 5, 2021

February 16, 2021

$32.8125

November 4, 2020

November 16, 2020

$32.8125

August 3, 2020

August 17, 2020

$32.8125

May 1, 2020

May 15, 2020

$32.8125

February 4, 2020

February 18, 2020

$32.8125

November 1, 2019

November 15, 2019

$32.8125

August 2, 2019

August 15, 2019

$32.8125

May 3, 2019

May 15, 2019

$32.8125

February 4, 2019

February 15, 2019

$32.8125

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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Segment Reporting Disclosure [Text Block]

Segment Information

12 Months Ended

Dec. 31, 2021

Segment Reporting [Abstract]

13. Segment Information

The following tables present reconciliations of Net Income Attributable to Boston Properties, Inc. Common Shareholders to the Company’s share of Net Operating Income and Net Income Attributable to Boston Properties Limited Partnership Common Unitholders to the Company’s share of Net Operating Income for the years ended December 31, 2021, 2020 and 2019.

Boston Properties, Inc.


	Year ended December 31,
		2021		2020		2019
		(in thousands)
Net income attributable to Boston Properties, Inc. common shareholders		$	496,223	$	862,227	$	511,034
Add:
Preferred stock redemption charge		6,412		—		—
Preferred dividends		2,560		10,500		10,500
Noncontrolling interest—common units of the Operating Partnership		55,931		97,704		59,345
Noncontrolling interests in property partnerships		70,806		48,260		71,120
Interest expense		423,346		431,717		412,717
Losses from early extinguishment of debt		45,182		—		29,540
Impairment loss		—		—		24,038
Net operating income from unconsolidated joint ventures		107,756		94,943		97,716
Depreciation and amortization expense		717,336		683,751		677,764
Transaction costs		5,036		1,531		1,984
Payroll and related costs from management services contracts		12,487		11,626		10,386
General and administrative expense		151,573		133,112		140,777
Less:
Net operating income attributable to noncontrolling interests in property partnerships		186,304		162,887		183,989
Gains from investments in securities		5,626		5,261		6,417
Interest and other income (loss)		5,704		5,953		18,939
Gains on sales of real estate		123,660		618,982		709
Income (loss) from unconsolidated joint ventures		(2,570)		(85,110)		46,592
Direct reimbursements of payroll and related costs from management services contracts		12,487		11,626		10,386
Development and management services revenue		27,697		29,641		40,039
Company’s share of Net Operating Income		$	1,735,740	$	1,626,131	$	1,739,850

Boston Properties Limited Partnership


	Year ended December 31,
		2021		2020		2019
		(in thousands)
Net income attributable to Boston Properties Limited Partnership common unitholders		$	561,993	$	979,979	$	580,102
Add:
Preferred unit redemption charge		6,412		—		—
Preferred distributions		2,560		10,500		10,500
Noncontrolling interests in property partnerships		70,806		48,260		71,120
Interest expense		423,346		431,717		412,717
Losses from early extinguishment of debt		45,182		—		29,540
Impairment loss		—		—		22,272
Net operating income from unconsolidated joint ventures		107,756		94,943		97,716
Depreciation and amortization expense		709,035		676,666		669,956
Transaction costs		5,036		1,531		1,984
Payroll and related costs from management services contracts		12,487		11,626		10,386
General and administrative expense		151,573		133,112		140,777
Less:
Net operating income attributable to noncontrolling interests in property partnerships		186,304		162,887		183,989
Gains from investments in securities		5,626		5,261		6,417
Interest and other income (loss)		5,704		5,953		18,939
Gains on sales of real estate		125,198		631,945		858
Income (loss) from unconsolidated joint ventures		(2,570)		(85,110)		46,592
Direct reimbursements of payroll and related costs from management services contracts		12,487		11,626		10,386
Development and management services revenue		27,697		29,641		40,039
Company’s share of Net Operating Income		$	1,735,740	$	1,626,131	$	1,739,850

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, impairment loss, depreciation and amortization expense, transaction costs, payroll and related costs from management services contracts and corporate general and administrative expense less (2) gains 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 and gain on sale of investment from unconsolidated joint ventures, both of which are included within Loss 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, impairment loss, depreciation and amortization expense, transaction costs, payroll and related costs from management services contracts, corporate general and administrative expense, gains 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, Seattle and Washington, DC. On September 1, 2021, the Company invested in a joint venture that acquired Safeco Plaza located in Seattle, Washington (See Note 6). As such, the Seattle region was identified as a segment during the third quarter of 2021. 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. Any write-off for bad debt, including accrued rent, will be recorded as a reduction to lease revenue. During the year ended December 31, 2021 and 2020, the Company wrote off approximately $1.3 million and $90.3 million, respectively, related to accrued rent, net balances and accounts receivable, net balances. The write-offs were for tenants, primarily in the retail and co-working sectors, that either terminated their leases or for which the Company determined their accrued rent and/or accounts receivable balances were no longer probable of collection.

Parking and other revenue for the year ended December 31, 2021 increased by approximately $11.1 million compared to the year ended December 31, 2020. Parking and other revenue for the year ended December 31, 2020 decreased by approximately $32.9 million compared to 2019. 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 has operated at lower occupancy levels due to the continued impact of COVID-19 on business and leisure travel. The closing of the hotel for more than two fiscal quarters, and the decreased demand and 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 year ended December 31, 2021:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Office	$	930,560		$	—		$	1,012,172		$	508,620		$	—		$	340,808		$	2,792,160
Residential	13,397			—			—			3,892			—			25,379			42,668
Hotel	13,609			—			—			—			—			—			13,609
Total	957,566			—			1,012,172			512,512			—			366,187			2,848,437
% of Grand Totals	33.62		%	—		%	35.53		%	17.99		%	—		%	12.86		%	100.00		%
Rental Expenses:
Office	322,298			—			379,267			168,040			—			127,102			996,707
Residential	5,811			—			—			6,717			—			11,916			24,444
Hotel	12,998			—			—			—			—			—			12,998
Total	341,107			—			379,267			174,757			—			139,018			1,034,149
% of Grand Totals	32.98		%	—		%	36.67		%	16.90		%	—		%	13.45		%	100.00		%
Net operating income	$	616,459		$	—		$	632,905		$	337,755		$	—		$	227,169		$	1,814,288
% of Grand Totals	33.98		%	—		%	34.88		%	18.62		%	—		%	12.52		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(43,232)			—			(143,072)			—			—			—			(186,304)
Add: Company’s share of net operating income from unconsolidated joint ventures	16,551			51,641			(664)			14,152			2,498			23,578			107,756
Company’s share of net operating income	$	589,778		$	51,641		$	489,169		$	351,907		$	2,498		$	250,747		$	1,735,740
% of Grand Totals	33.98		%	2.98		%	28.18		%	20.27		%	0.14		%	14.45		%	100.00		%

_______________

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

For the year ended December 31, 2020:


	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	897,915		$	—		$	935,966		$	508,327		$	336,587		$	2,678,795
Residential	13,616			—			—			155			24,375			38,146
Hotel	7,478			—			—			—			—			7,478
Total	919,009			—			935,966			508,482			360,962			2,724,419
% of Grand Totals	33.73		%	—		%	34.36		%	18.66		%	13.25		%	100.00		%
Rental Expenses:
Office	318,509			—			384,753			163,156			132,051			998,469
Residential	5,378			—			—			2,261			11,100			18,739
Hotel	13,136			—			—			—			—			13,136
Total	337,023			—			384,753			165,417			143,151			1,030,344
% of Grand Totals	32.71		%	—		%	37.35		%	16.05		%	13.89		%	100.00		%
Net operating income	$	581,986		$	—		$	551,213		$	343,065		$	217,811		$	1,694,075
% of Grand Totals	34.35		%	—		%	32.54		%	20.25		%	12.86		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(41,849)			—			(121,038)			—			—			(162,887)
Add: Company’s share of net operating income from unconsolidated joint ventures	10,765			57,907			(5,326)			14,928			16,669			94,943
Company’s share of net operating income	$	550,902		$	57,907		$	424,849		$	357,993		$	234,480		$	1,626,131
% of Grand Totals	33.88		%	3.56		%	26.12		%	22.02		%	14.42		%	100.00		%

_______________

For the year ended December 31, 2019:


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

_______________

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.

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Earnings Per Share / Common Unit

Earnings Per Share / Common Unit

12 Months Ended

Dec. 31, 2021

Earnings Per Share [Abstract]

14. Earnings Per Share / Common Unit

Boston Properties, Inc.

The following table provides a reconciliation of both the net income attributable to Boston Properties, Inc. common shareholders and the number of common shares used in the computation of basic earnings per share (“EPS”), which is calculated by dividing net income attributable to Boston Properties, Inc. common shareholders by the weighted-average number of common shares outstanding during the period. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of Boston Properties, Inc. and Boston Properties Limited Partnership’s LTIP Units, 2012 OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic EPS of Boston Properties, Inc. using the two-class method. Participating securities are included in the computation of diluted EPS of Boston Properties, Inc. using the if-converted method if the impact is dilutive. Because the 2012 OPP Units 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.


	Year ended December 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	$	496,223	156,116	$	3.18
Effect of Dilutive Securities:
Stock Based Compensation	—		260	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,223	156,376	$	3.17

	Year ended December 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	$	862,227	155,432	$	5.55
Allocation of undistributed earnings to participating securities	(748)		—	(0.01)
Net income attributable to Boston Properties, Inc. common shareholders	$	861,479	155,432	$	5.54
Effect of Dilutive Securities:
Stock Based Compensation	—		85	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	861,479	155,517	$	5.54

	Year ended December 31, 2019
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:


Net income attributable to Boston Properties, Inc. common shareholders	$	511,034	154,582	$	3.31
Effect of Dilutive Securities:
Stock Based Compensation	—		301	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	511,034	154,883	$	3.30

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 17,034,000, 17,211,000 and 17,618,000 redeemable common units for the years ended December 31, 2021, 2020 and 2019, respectively.


	Year ended December 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	$	561,993	173,150	$	3.25
Effect of Dilutive Securities:
Stock Based Compensation	—		260	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	561,993	173,410	$	3.24

	Year ended December 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	$	979,979	172,643	$	5.68
Allocation of undistributed earnings to participating securities	(830)		—	(0.01)
Net income attributable to Boston Properties Limited Partnership common unitholders	$	979,149	172,643	$	5.67
Effect of Dilutive Securities:
Stock Based Compensation	—		85	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	979,149	172,728	$	5.67


	Year ended December 31, 2019
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:


Net income attributable to Boston Properties Limited Partnership common unitholders	$	580,102	172,200	$	3.37
Effect of Dilutive Securities:
Stock Based Compensation	—		301	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	580,102	172,501	$	3.36

Employee Benefits Plan	12 Months Ended
Employee Benefits Plan	Dec. 31, 2021
Disclosure Text Block Supplement [Abstract]
Employee Benefit Plans	15. Employee Benefit Plans Effective January 1, 1985, the predecessor of the Company adopted a 401(k) Savings Plan (the “Plan”) for its employees. Upon formation, the Company adopted the Plan and the terms of the Plan. Under the Plan, as amended, the Company’s matching contribution equals 200% of the first 3% of participant’s eligible earnings contributed (utilizing earnings that are not in excess of an amount established by the IRS ($290,000, $285,000 and $280,000 in 2021, 2020 and 2019, respectively), indexed for inflation) with no vesting requirement. The Company’s aggregate matching contribution for the years ended December 31, 2021, 2020 and 2019 was approximately $4.7 million, $4.0 million and $4.2 million, respectively. The Company also maintains a deferred compensation plan that is designed to allow officers of Boston Properties, Inc. to defer a portion of the officer’s current income on a pre-tax basis and receive a tax-deferred return on these deferrals based on the performance of specific investments selected by the officer. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2021 and 2020, the Company had maintained approximately $42.7 million and $38.6 million, respectively, in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the plan participants and earnings on the deferred compensation pursuant to investments elected by the plan participants. The Company’s liability as of December 31, 2021 and 2020 was approximately $42.7 million and $38.6 million, respectively, which are included in the accompanying Consolidated Balance Sheets.

Stock Option and Incentive Plan

12 Months Ended

Dec. 31, 2021

Share-based Payment Arrangement [Abstract]

Stock Option and Incentive Plan

16. 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 peer 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, will equal 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.

At Boston Properties, Inc.’s 2021 annual meeting of stockholders held on May 20, 2021, its stockholders approved the Boston Properties, Inc. 2021 Stock Incentive Plan (the “2021 Plan”). The 2021 Plan replaces the 2012 Plan and no further awards will be granted under the 2012 Plan. The material features of the 2021 Plan include, among other things: (i) the maximum number of shares of common stock reserved and available for issuance under the 2021 Plan is 5,400,000 shares less one share for every one share that was granted between March 4, 2021 and May 19, 2021 under the 2012 Plan, (ii) shares of common stock underlying awards granted under the 2021 Plan or the 2012 Plan that are forfeited, canceled or otherwise terminated (other than by exercise) will be added back to the shares of common stock available for issuance under the 2021 Plan and, with respect to “full-value” awards under the 2021 Plan or the 2012 Plan, shares tendered or held back for taxes and shares previously reserved for issuance pursuant to such an award to the extent that such shares are not issued and are no longer issuable pursuant to such an award (e.g., in the event that a full-value award that may be settled in cash or by issuance of shares of common stock is settled in cash) will be added back to the shares available for issuance under the 2021 Plan, (iii) the award of stock options (both incentive and non-qualified options), stock appreciation rights, restricted stock units, restricted stock, unrestricted stock, dividend equivalent rights, cash-based awards and other equity-based awards (including LTIP Units) is permitted, (iv) stock options may not be repriced and “underwater” stock options may not be exchanged for another award or cash without stockholder approval; and (v) the term of the 2021 Plan is for ten years from the date of stockholder approval.

Boston Properties, Inc. issued 57,383, 29,630 and 26,503 shares of restricted common stock and Boston Properties Limited Partnership issued 281,640, 207,181 and 181,919 LTIP Units to employees and non-employee directors under the 2012 Plan and the 2021 Plan during the years ended December 31, 2021, 2020 and 2019, respectively. Boston Properties, Inc. did not issue any non-qualified stock options under the 2012 Plan during the years ended December 31, 2021, 2020 and 2019. Boston Properties Limited Partnership issued 352,021 2021 MYLTIP Units, 203,278 2020 MYLTIP Units and 220,734 2019 MYLTIP Units to employees under the 2012 Plan during the years ended December 31, 2021, 2020 and 2019, respectively. Employees and non-employee directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit and MYLTIP Unit. When issued, LTIP Units are not economically equivalent in value to a share of Common Stock, but over time can increase in value to

one-for-one parity with Common Stock if there is sufficient appreciation in the value of the Company’s assets. The aggregate value of the LTIP Units is included in noncontrolling interests in the Consolidated Balance Sheets of Boston Properties, Inc. and Boston Properties Limited Partnership. A 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. 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 $49.7 million, $43.0 million and $39.8 million for the years ended December 31, 2021, 2020 and 2019, respectively. At December 31, 2021, there was (1) an aggregate of approximately $22.5 million of unrecognized compensation expense related to unvested restricted stock and LTIP Units and (2) an aggregate of approximately $7.4 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 2.0 years.

The shares of restricted stock were valued at approximately $5.8 million ($100.60 per share weighted-average), $4.0 million ($133.81 per share weighted-average) and $3.5 million ($131.27 per share weighted-average) for the years ended December 31, 2021, 2020 and 2019, respectively.

LTIP Units were valued using a Monte Carlo simulation method model in accordance with the provisions of ASC 718. LTIP Units issued during the years ended December 31, 2021, 2020 and 2019 were valued at approximately $23.8 million, $26.3 million and $22.1 million, respectively. The weighted-average per unit fair value of LTIP Unit grants in 2021, 2020 and 2019 was $84.43, $127.14 and $121.50, respectively. The per unit fair value of each LTIP Unit granted in 2021, 2020 and 2019 was estimated on the date of grant using the following assumptions; an expected life of 5.7 years, 5.7 years and 5.7 years, a risk-free interest rate of 0.65%, 1.47% and 2.68% and an expected price volatility of 30.0%, 18.0% and 27.0%, respectively.

There were no non-qualified stock options granted during the years ended December 31, 2021, 2020 and 2019.

A summary of the status of Boston Properties, Inc.’s stock options as of December 31, 2021, 2020 and 2019 and changes during the years then ended are presented below:


	Shares	Weighted-Average Exercise Price
Outstanding at December 31, 2018	540,441	$	96.35
Exercised	(145,088)	$	96.27
Outstanding at December 31, 2019	395,353	$	96.37
Exercised	(43,792)	$	91.60
Outstanding at December 31, 2020	351,561	$	96.97
Exercised	(247,920)	$	96.95
Outstanding at December 31, 2021	103,641	$	97.01

The following table summarizes information about Boston Properties, Inc.’s stock options outstanding at December 31, 2021:


Options Outstanding				Options Exercisable
Number Outstanding at 12/31/21	Weighted-Average Remaining Contractual Life	Exercise Price		Number Exercisable at 12/31/21	Exercise Price
54,282	1.3 years	$	95.69	54,282	$	95.69
49,359	1.1 years	$	98.46	49,359	$	98.46

The total intrinsic value of the outstanding and exercisable stock options as of December 31, 2021 was approximately $1.9 million. In addition, Boston Properties, Inc. had 103,641 and 351,561 options exercisable at a weighted-average exercise price of $97.01 and $96.97 at December 31, 2021 and 2020, respectively.

Boston Properties, Inc. adopted the 1999 Non-Qualified Employee Stock Purchase Plan (the “Stock Purchase Plan”) to encourage the ownership of Common Stock by eligible employees. The Stock Purchase Plan became effective on January 1, 1999 with an aggregate maximum of 250,000 shares of Common Stock available for issuance. The Stock Purchase Plan provides for eligible employees to purchase on the business day immediately following the end of the biannual purchase periods (i.e., January 1-June 30 and July 1-December 31) shares of Common Stock at a purchase price equal to 85% of the average closing prices of the Common Stock during the last ten business days of the purchase period. Boston Properties, Inc. issued 9,846, 7,195 and 5,862 shares with the weighted-average purchase price equal to $89.73 per share, $90.53 per share and $104.11 per share under the Stock Purchase Plan during the years ended December 31, 2021, 2020 and 2019, respectively.

Related Party Disclosures	12 Months Ended
Related Party Disclosures	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions Disclosure	17. Related Party Transactions A firm controlled by Mr. Raymond A. Ritchey’s brother was paid aggregate leasing commissions of approximately $0, $914,000 and $21,000 during the years ended December 31, 2021, 2020 and 2019, respectively, related to certain exclusive leasing arrangements for certain Northern Virginia properties. In addition, Mr. Ritchey’s brother is employed by a real estate brokerage firm and participated in brokerage activities for which the Company paid the firm approximately $1.9 million, $3.4 million and $2.6 million for the years ended December 31, 2021, 2020 and 2019, respectively. Mr. Ritchey is a Senior Executive Vice President of Boston Properties, Inc. On July 13, 2018, the Company entered into a joint venture with a third party to acquire a development site at 3 Hudson Boulevard that, upon the future acquisition of additional available development rights, can accommodate a Class A office tower with up to 2.0 million net rentable square feet located on the entire square block between 11th Avenue and Hudson Boulevard Park from West 34th Street to West 35th Street in New York City. The Company owns a 25% interest in, and is the managing member of, the joint venture. The Company provided $80.0 million of mortgage financing to the joint venture that bears interest at a variable rate equal to LIBOR plus 3.50% per annum and matures on July 13, 2023, with extension options, subject to certain conditions. The loan has been reflected as a Related Party Note Receivable on the Company’s Consolidated Balance Sheets. The Company has recognized interest income of approximately $3.6 million, $2.7 million and $2.5 million for the years ended December 31, 2021, 2020 and 2019, respectively. The Company's policy is to record notes receivable at their unamortized cost, net of any unamortized deferred fees or costs, premiums or discounts and an allowance for loan losses. Loan fees and direct costs associated with loans originated by the Company are deferred and amortized over the term of the note as interest income. In accordance with the 2021 Plan, and as approved by its Board of Directors, seven non-employee directors made elections to receive deferred stock units in lieu of cash fees for 2021. As a result of these elections, the aggregate cash fees otherwise payable to a non-employee director during a fiscal quarter are converted into a number of deferred stock units equal to the aggregate cash fees divided by the last reported sales price of a share of Boston Properties, Inc.’s Common Stock on the last trading of the applicable fiscal quarter. The deferred stock units are also credited with dividend equivalents as dividends are paid by Boston Properties, Inc. The deferred stock units may be settled in shares of Common Stock upon the cessation of such director’s service on the Board of Directors of Boston Properties, Inc. The non-employee director compensation program provides, subject to certain conditions, the non-employee directors holding deferred stock units with the ability to elect, following cessation of their service on the Company’s Board of Directors, to diversify their investment elections into non-employer securities on a pre-tax basis and receive tax-deferred returns on such deferrals, which will ultimately be settled in cash. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the non-employee director in the future. At December 31, 2021 and 2020, the Company had maintained approximately $0.9 million and $0.8 million, respectively, in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the non-employee director and earnings on the deferred compensation pursuant to investments elected by the non-employee director. The Company’s liability as of December 31, 2021 and 2020 was approximately $0.9 million and $0.8 million, respectively, which is included in the accompanying Consolidated Balance Sheets. The terms of the non-employee director compensation program require the classification of these deferred stock units as temporary equity on the Consolidated Balance Sheets of Boston Properties, Inc. and Boston Properties Limited Partnership within Redeemable Deferred Stock Units. On December 16, 2021, in connection with the resignation of a director’s service on the Board of Directors of Boston Properties, Inc., Boston Properties, Inc. issued 498 shares of Common Stock in settlement of the director’s outstanding deferred stock units. At December 31, 2021 and 2020, Boston Properties, Inc. had outstanding 83,073 and 72,966 deferred stock units, respectively.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	18. Subsequent Events On January 18, 2022, a joint venture in which the Company has a 50% interest, commenced the redevelopment of 651 Gateway located in South San Francisco, California. 651 Gateway is an approximately 293,000 net rentable square foot office building that will be converted to life sciences space. The project is expected to be completed in late 2023. On January 28, 2022 and February 1, 2022, Boston Properties, Inc. issued an aggregate of 33,091 shares of restricted common stock and Boston Properties Limited Partnership issued an aggregate of 249,873 LTIP Units under the 2021 Plan to certain employees of Boston Properties, Inc. On February 1, 2022, Boston Properties, Inc.’s Compensation Committee approved the 2022 Multi-Year Long-Term Incentive Program (the “2022 MYLTIP”) awards under the 2021 Plan to certain officers and employees of Boston Properties, Inc. Earned awards will range from zero to a maximum of 254,061 LTIP Units depending on Boston Properties, Inc.’s relative and absolute TSR performance with a target of approximately 127,031 LTIP Units. Under ASC 718, the 2022 MYLTIP awards have an aggregate value of approximately $17.3 million. On February 2, 2022, a joint venture in which the Company has a 55% interest recommenced the development of Platform 16, a Class A office project located in San Jose, California, that is expected to be approximately 1.1 million square feet upon completion. The first phase of the development project will include the construction of an approximately 390,000 square foot Class A creative office building and a below-grade parking garage, which are expected to be completed in early 2025. On February 4, 2022, the measurement period for the Company’s 2019 MYLTIP awards ended and, based on Boston Properties, Inc.’s relative TSR performance, the final payout was determined to be 69.0% of target, or an aggregate of approximately $8.6 million (after giving effect to employee separations). As a result, an aggregate of 144,043 2019 MYLTIP Units that had been previously granted were automatically forfeited.

SEC Schedule, Article 12-28, Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2021

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

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

Item 15. Exhibits and Financial Statement Schedules.

(a) Financial Statement Schedule


Boston Properties, Inc. Schedule 3—Real Estate and Accumulated Depreciation December 31, 2021 (dollars in thousands)
Property Name	Type	Location	Encumbrances		Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

					Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,281,016	$	1,796,252	$	1,532,654	$	260,700	$	1,796,252	$	1,793,354	$	—	$	—	$	3,589,606	$	407,377	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—		92,077		948,357		615,973		115,637		1,483,065		192		57,513		1,656,407		678,000		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—		179,697		847,410		480,465		195,987		1,311,585		—		—		1,507,572		692,283		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—		339,200		700,358		366,449		354,107		1,051,900		—		—		1,406,007		405,104		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	986,898		241,600		494,782		486,028		289,639		932,771		—		—		1,222,410		325,012		1977/1997/2021	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—		200,349		946,205		7,515		200,349		953,720		—		—		1,154,069		99,152		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—		219,543		667,884		222,640		250,560		859,507		—		—		1,110,067		277,388		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—		285,263		603,167		52,298		285,263		655,465		—		—		940,728		159,238		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—		131,067		435,954		138,727		131,067		574,681		—		—		705,748		157,939		1971-1975/2017	2012	(1)
Times Square Tower	Office	New York, NY	—		165,413		380,438		115,843		169,193		492,501		—		—		661,694		232,128		2004	2000	(1)
Carnegie Center	Office	Princeton, NJ	—		142,666		316,856		159,350		94,240		469,216		55,416		—		618,872		236,695		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Atlantic Wharf	Office	Boston, MA	—		63,988		454,537		19,831		63,988		474,368		—		—		538,356		156,879		2011	2007	(1)
599 Lexington Avenue	Office	New York, NY	—		81,040		100,507		247,001		87,852		340,696		—		—		428,548		179,928		1986	1997	(1)
Fountain Square	Office	Reston, VA	—		56,853		306,298		29,595		56,853		335,893		—		—		392,746		94,501		1986-1990	2012	(1)
510 Madison Avenue	Office	New York, NY	—		103,000		253,665		28,825		103,000		282,490		—		—		385,490		90,673		2012	2010	(1)
680 Folsom Street	Office	San Francisco, CA	—		72,545		219,766		8,026		72,545		227,792		—		—		300,337		63,864		2014	2012	(1)
145 Broadway	Office	Cambridge, MA	—		121		273,013		25,992		23,367		275,759		—		—		299,126		18,393		2019	1997	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—		—		183,541		110,980		105,787		188,734		—		—		294,521		71,983		2011	2008	(1)
South of Market and Democracy Tower	Office	Reston, VA	—		13,603		237,479		21,882		13,687		259,277		—		—		272,964		94,354		2008-2009	2003	(1)
601 Massachusetts Avenue	Office	Washington, DC	—		95,310		165,173		3,965		95,322		169,126		—		—		264,448		36,983		2016	2008	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—		18,789		148,451		80,753		18,789		229,144		60		—		247,993		97,149		1985-1989	2011	(1)
535 Mission Street	Office	San Francisco, CA	—		40,933		148,378		3,501		40,933		151,879		—		—		192,812		37,477		2015	2013	(1)
Mountain View Research Park	Office	Mountain View, CA	—		95,066		68,373		16,801		95,066		85,174		—		—		180,240		24,149		1977-1981/2007-2013	2013	(1)
Reservoir Place	Office	Waltham, MA	—		18,605		104,124		53,945		20,108		156,275		291		—		176,674		79,338		1955/1987/2017	1997/1998	(1)
1330 Connecticut Avenue	Office	Washington, DC	—		25,982		82,311		37,161		27,135		118,319		—		—		145,454		43,174		1984/2018	2004	(1)
One Freedom Square	Office	Reston, VA	—		9,929		84,504		41,978		11,293		125,118		—		—		136,411		60,550		2000	2003	(1)
Kingstowne Towne Center	Office	Alexandria, VA	—		18,021		109,038		3,875		18,062		112,872		—		—		130,934		49,475		2003-2006	2007	(1)


Boston Properties, Inc. Schedule 3—Real Estate and Accumulated Depreciation December 31, 2021 (dollars in thousands)
Property Name	Type	Location	Encumbrances	Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

				Land	Building
One and Two Reston Overlook	Office	Reston, VA	—	16,456	66,192	40,694	16,179	107,163	—	—	123,342	55,487	1999	2000	(1)
140 Kendrick Street	Office	Needham, MA	—	18,095	66,905	37,813	19,092	103,721	—	—	122,813	40,242	2000	2004	(1)
Shady Grove Innovation District	Office	Rockville, MD	—	52,030	64,212	2,676	26,834	34,974	57,110	—	118,918	1,048	1968-1985	2021	(1)
Weston Corporate Center	Office	Weston, MA	—	25,753	92,312	32	25,854	92,243	—	—	118,097	35,329	2010	2001	(1)
17Fifty Presidents Street	Office	Reston, VA	—	—	113,362	44	—	113,406	—	—	113,406	7,840	2020	2013	(1)
Discovery Square	Office	Reston, VA	—	11,198	71,782	21,304	12,533	91,751	—	—	104,284	50,358	2001	2003	(1)
355 Main Street	Office	Cambridge, MA	—	18,863	53,346	24,995	21,173	76,031	—	—	97,204	31,827	1981/1996/2013	2006	(1)
10 CityPoint	Office	Waltham, MA	—	1,953	85,752	6,963	2,290	92,378	—	—	94,668	17,327	2016	1997	(1)
Two Freedom Square	Office	Reston, VA	—	13,930	77,739	(184)	15,420	76,065	—	—	91,485	33,696	2001	2003	(1)
90 Broadway	Office	Cambridge, MA	—	19,104	52,078	18,876	20,785	69,273	—	—	90,058	26,797	1983/1998/2013	2006	(1)
153 & 211 Second Avenue	Office	Waltham, MA	—	33,233	55,940	—	33,233	55,940	—	—	89,173	1,819	1964-2006	2021	(1)
230 CityPoint	Office	Waltham, MA	—	13,189	49,823	23,874	13,807	73,079	—	—	86,886	35,469	1992	2005	(1)
77 CityPoint	Office	Waltham, MA	—	13,847	60,383	11,524	14,023	71,731	—	—	85,754	31,832	2008	2001	(1)
20 CityPoint	Office	Waltham, MA	—	4,887	72,764	7,071	4,887	79,835	—	—	84,722	6,135	2020	2007	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—	10,385	60,694	12,662	11,097	72,644	—	—	83,741	40,253	2003	1999	(1)
200 West Street	Office	Waltham, MA	—	16,148	24,983	39,592	16,813	63,593	317	—	80,723	19,724	1999/2021	1997	(1)
Sumner Square	Office	Washington, DC	—	624	28,745	49,345	28,548	50,166	—	—	78,714	29,871	1985	1999	(1)
2440 West El Camino Real	Office	Mountain View, CA	—	16,741	51,285	6,290	16,741	57,575	—	—	74,316	17,265	1987/2003	2011	(1)
300 Binney Street	Office	Cambridge, MA	—	18,080	51,262	140	18,080	51,402	—	—	69,482	14,537	2013	2009	(1)
Reston Corporate Center	Office	Reston, VA	—	9,135	50,857	6,236	10,148	56,080	—	—	66,228	32,950	1984	1998	(1)
Wisconsin Place	Office	Chevy Chase, MD	—	—	53,349	12,600	—	65,949	—	—	65,949	28,025	2009	2004	(1)
255 Main Street	Office	Cambridge, MA	—	134	25,110	34,260	548	58,956	—	—	59,504	39,791	1987	1997	(1)
University Place	Office	Cambridge, MA	—	—	37,091	16,512	6,004	47,599	—	—	53,603	33,469	1985	1998	(1)
890 Winter Street	Office	Waltham, MA	—	13,913	28,557	4,745	13,913	33,302	—	—	47,215	3,928	1999	2019	(1)
Capital Gallery	Office	Washington, DC	—	4,725	29,565	9,681	8,662	35,309	—	—	43,971	21,562	1981/2006	2007	(1)
North First Business Park	Office	San Jose, CA	—	23,398	13,069	4,545	23,377	17,635	—	—	41,012	17,017	1981	2007	(1)
150 Broadway	Office	Cambridge, MA	—	850	25,042	2,350	1,323	26,919	—	—	28,242	14,833	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—	1,299	12,943	12,723	2,395	24,570	—	—	26,965	14,309	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—	998	1,426	18,582	1,264	19,551	191	—	21,006	16,012	1982	1997	(1)
The Point	Office	Waltham, MA	—	6,395	10,040	421	6,492	10,364	—	—	16,856	1,984	2015	2007	(1)
690 Folsom Street	Office	San Francisco, CA	—	3,219	11,038	1,877	3,219	12,915	—	—	16,134	3,354	2015	2012	(1)
195 West Street	Office	Waltham, MA	—	1,611	6,652	7,470	1,858	13,875	—	—	15,733	8,842	1990	1997	(1)
33 Hayden Avenue	Office	Lexington, MA	—	266	3,234	11,501	425	14,576	—	—	15,001	6,768	1979	1997	(1)
92-100 Hayden Avenue	Office	Lexington, MA	—	594	6,748	6,259	802	12,799	—	—	13,601	11,468	1985	1997	(1)
7501 Boston Boulevard, Building Seven	Office	Springfield, VA	—	665	9,273	819	791	9,966	—	—	10,757	5,937	1997	1997	(1)


Boston Properties, Inc. Schedule 3—Real Estate and Accumulated Depreciation December 31, 2021 (dollars in thousands)
Property Name	Type	Location	Encumbrances	Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

				Land	Building
7435 Boston Boulevard, Building One	Office	Springfield, VA	—	392	3,822	5,016	659	8,571	—	—	9,230	7,010	1982	1997	(1)
32 Hartwell Avenue	Office	Lexington, MA	—	168	1,943	6,944	314	8,741	—	—	9,055	2,734	1968/1979/1987	1997	(1)
7450 Boston Boulevard, Building Three	Office	Springfield, VA	—	1,165	4,681	2,613	1,430	7,029	—	—	8,459	4,774	1987	1998	(1)
250 Binney Street	Office	Cambridge, MA	—	110	4,483	3,593	273	7,913	—	—	8,186	6,593	1983	1997	(1)
8000 Grainger Court, Building Five	Office	Springfield, VA	—	366	4,282	3,198	601	7,245	—	—	7,846	6,093	1984	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—	5,477	1,090	676	5,477	1,766	—	—	7,243	924	1977	2012	(1)
7300 Boston Boulevard, Building Thirteen	Office	Springfield, VA	—	608	4,773	1,075	661	5,795	—	—	6,456	2,527	2002	1997	(1)
17 Hartwell Avenue	Office	Lexington, MA	—	26	150	6,078	65	6,189	—	—	6,254	3,009	1968	1997	(1)
7601 Boston Boulevard, Building Eight	Office	Springfield, VA	—	200	878	5,045	551	5,572	—	—	6,123	4,986	1986	1997	(1)
7500 Boston Boulevard, Building Six	Office	Springfield, VA	—	138	3,749	1,714	367	5,234	—	—	5,601	4,536	1985	1997	(1)
8000 Corporate Court, Building Eleven	Office	Springfield, VA	—	136	3,071	1,903	774	4,336	—	—	5,110	3,455	1989	1997	(1)
7375 Boston Boulevard, Building Ten	Office	Springfield, VA	—	23	2,685	1,005	93	3,620	—	—	3,713	2,841	1988	1997	(1)
7451 Boston Boulevard, Building Two	Office	Springfield, VA	—	249	1,542	1,858	613	3,036	—	—	3,649	2,806	1982	1997	(1)
7374 Boston Boulevard, Building Four	Office	Springfield, VA	—	241	1,605	1,664	398	3,112	—	—	3,510	2,787	1984	1997	(1)
The Skylyne	Residential	Oakland, CA	—	28,962	239,077	1,097	28,962	240,174	—	—	269,136	8,132	2020	N/A	(1)
Signature at Reston	Residential	Reston, VA	—	27,076	190,580	838	27,076	191,418	—	—	218,494	18,534	2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—	9,243	127,248	3,336	9,245	130,582	—	—	139,827	11,195	2018	2015	(1)
The Avant at Reston Town Center	Residential	Reston, VA	—	20,350	91,995	846	20,350	92,841	—	—	113,191	19,681	2014	2010	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—	3,529	54,891	2,215	3,529	57,106	—	—	60,635	15,689	2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—	478	37,918	35,117	1,201	72,312	—	—	73,513	51,600	1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—	—	35,035	6,846	103	41,778	—	—	41,881	15,818	1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—	1,256	15,697	1,552	1,434	17,071	—	—	18,505	6,939	2006	2004	(1)
Kendall Center Blue Garage	Garage	Cambridge, MA	—	1,163	11,633	2,111	1,579	13,328	—	—	14,907	10,399	1990	1997	(1)
Reston Next	Development	Reston, VA	—	—	—	514,182	2,901	250,135	—	261,146	514,182	1,631	N/A	1998	N/A
2100 Pennsylvania Avenue	Development	Washington, DC	—	—	—	393,094	185,203	—	—	207,891	393,094	5,941	N/A	N/A	N/A
325 Main Street	Development	Cambridge, MA	—	174	—	286,000	965	—	—	285,209	286,174	—	N/A	1997	N/A
880 Winter Street	Development	Waltham, MA	—	15,597	37,255	(667)	15,597	19,614	—	16,974	52,185	1,247	1998	2019	N/A
180 CityPoint	Development	Waltham, MA	—	—	—	50,776	—	—	—	50,776	50,776	—	N/A	2006	N/A
103 CityPoint	Development	Waltham, MA	—	—	—	14,663	—	—	—	14,663	14,663	—	N/A	2007	N/A
777 Harrison Street	Land	San Francisco, CA	—	144,647	—	26,800	—	47	171,400	—	171,447	11	N/A	2020	N/A
3625-3635 Peterson Way	Land	Santa Clara, CA	—	63,206	—	4,541	—	—	67,747	—	67,747	—	N/A	2016	N/A


Boston Properties, Inc. Schedule 3—Real Estate and Accumulated Depreciation December 31, 2021 (dollars in thousands)
Property Name	Type	Location	Encumbrances			Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements			Building and Improvements			Land Held for Development			Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)

						Land		Building
Back Bay Station Master Plan	Land	Boston, MA	—			—		—		53,432		—			—			53,432			—		53,432		—		N/A	N/A	N/A
North First Master Plan	Land	San Jose, CA	—			35,004		—		3,941		—			—			38,945			—		38,945		—		N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—			—		—		37,418		—			—			37,418			—		37,418		—		N/A	2006	N/A
Reston Gateway Master Plan	Land	Reston, VA	—			—		—		30,945		—			—			30,945			—		30,945		—		N/A	1998	N/A
Springfield Metro Center	Land	Springfield, VA	—			—		—		19,887		—			—			19,887			—		19,887		—		N/A	2007	N/A
CityPoint South Master Plan	Land	Waltham, MA	—			—		—		14,890		—			—			14,890			—		14,890		—		N/A	N/A	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—			—		—		8,381		—			—			8,381			—		8,381		—		N/A	1997	N/A
Broad Run Business Park	Land	Loudoun County, VA	—			—		—		2,405		—			—			2,405			—		2,405		—		N/A	1998	N/A
Weston Quarry	Land	Weston, MA	—			—		—		1,249		—			—			1,249			—		1,249		—		N/A	2001	N/A
Reston Overlook Master Plan	Land	Reston, VA	—			—		—		79		—			—			79			—		79		—		N/A	2000	N/A

			$	3,267,914	(2)	$	5,238,614	$	13,216,859	$	5,652,747	$	5,445,112	(3)	$	17,208,581	(4)	$	560,355	(5)	$	894,172	$	24,108,220	$	5,848,183

Note: Total Real Estate does not include Furniture, Fixtures and Equipment totaling approximately $51,695. Accumulated Depreciation does not include approximately $35,778 of accumulated depreciation related to Furniture, Fixtures and Equipment.

The aggregate cost and accumulated depreciation for tax purposes was approximately $21.8 billion and $4.9 billion, respectively.

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

(2)Includes unamortized deferred financing costs totaling approximately $(32.1) million.

(3)Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $214,165 and $169,778, respectively.

(4)Includes Right of Use Assets - Finance Leases of approximately $23,342.

(5)Includes pre-development costs.

Boston Properties, Inc.

Real Estate and Accumulated Depreciation

December 31, 2021, 2020 and 2019

(dollars in thousands)

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


	2021		2020		2019
Real Estate:
Balance at the beginning of the year	$	23,303,303	$	22,844,697	$	21,605,545
Additions to/improvements of real estate	1,145,084		996,989		1,671,898
Assets sold/written-off	(340,167)		(538,383)		(432,746)
Balance at the end of the year	$	24,108,220	$	23,303,303	$	22,844,697
Accumulated Depreciation:
Balance at the beginning of the year	$	5,501,637	$	5,239,179	$	4,871,102
Depreciation expense	623,854		573,898		564,938
Assets sold/written-off	(277,308)		(311,440)		(196,861)
Balance at the end of the year	$	5,848,183	$	5,501,637	$	5,239,179

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


Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2021 (dollars in thousands)
					Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances		Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,281,016	$	1,796,252	$	1,532,654	$	260,700	$	1,796,252	$	1,793,354	$	—	$	—	$	3,589,606	$	407,377	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—		92,077		948,357		556,917		100,539		1,439,107		192		57,513		1,597,351		660,321		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—		179,697		847,410		418,084		180,420		1,264,771		—		—		1,445,191		673,363		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—		339,200		700,358		306,841		339,200		1,007,199		—		—		1,346,399		387,131		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	986,898		241,600		494,782		448,942		279,281		906,043		—		—		1,185,324		314,209		1977/1997/2021	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—		200,349		946,205		7,515		200,349		953,720		—		—		1,154,069		99,152		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—		219,543		667,884		222,640		250,560		859,507		—		—		1,110,067		277,388		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—		285,263		603,167		52,298		285,263		655,465		—		—		940,728		159,238		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—		131,067		435,954		138,727		131,067		574,681		—		—		705,748		157,939		1971-1975/2017	2012	(1)
Times Square Tower	Office	New York, NY	—		165,413		380,438		77,864		159,694		464,021		—		—		623,715		220,676		2004	2000	(1)
Carnegie Center	Office	Princeton, NJ	—		142,666		316,856		144,387		90,498		457,995		55,416		—		603,909		232,183		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Atlantic Wharf	Office	Boston, MA	—		63,988		454,537		19,831		63,988		474,368		—		—		538,356		156,879		2011	2007	(1)
599 Lexington Avenue	Office	New York, NY	—		81,040		100,507		219,759		81,040		320,266		—		—		401,306		171,713		1986	1997	(1)
Fountain Square	Office	Reston, VA	—		56,853		306,298		29,595		56,853		335,893		—		—		392,746		94,501		1986-1990	2012	(1)
510 Madison Avenue	Office	New York, NY	—		103,000		253,665		28,825		103,000		282,490		—		—		385,490		90,673		2012	2010	(1)
680 Folsom Street	Office	San Francisco, CA	—		72,545		219,766		8,026		72,545		227,792		—		—		300,337		63,864		2014	2012	(1)
145 Broadway	Office	Cambridge, MA	—		121		273,013		25,789		23,164		275,759		—		—		298,923		18,393		2019	1997	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—		—		183,541		110,980		105,787		188,734		—		—		294,521		71,983		2011	2008	(1)
South of Market and Democracy Tower	Office	Reston, VA	—		13,603		237,479		21,546		13,603		259,025		—		—		272,628		94,269		2008-2009	2003	(1)
601 Massachusetts Avenue	Office	Washington, DC	—		95,310		165,173		3,953		95,310		169,126		—		—		264,436		36,983		2016	2008	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—		18,789		148,451		80,753		18,789		229,144		60		—		247,993		97,149		1985-1989	2011	(1)
535 Mission Street	Office	San Francisco, CA	—		40,933		148,378		3,501		40,933		151,879		—		—		192,812		37,477		2015	2013	(1)
Mountain View Research Park	Office	Mountain View, CA	—		95,066		68,373		16,801		95,066		85,174		—		—		180,240		24,149		1977-1981/2007-2013	2013	(1)
Reservoir Place	Office	Waltham, MA	—		18,605		104,124		49,870		19,089		153,219		291		—		172,599		78,109		1955/1987/2017	1997/1998	(1)
1330 Connecticut Avenue	Office	Washington, DC	—		25,982		82,311		32,548		25,982		114,859		—		—		140,841		41,783		1984/2018	2004	(1)
One Freedom Square	Office	Reston, VA	—		9,929		84,504		36,341		9,883		120,891		—		—		130,774		58,850		2000	2003	(1)
Kingstowne Towne Center	Office	Alexandria, VA	—		18,021		109,038		3,711		18,021		112,749		—		—		130,770		49,433		2003-2006	2007	(1)
One and Two Reston Overlook	Office	Reston, VA	—		16,456		66,192		36,276		15,074		103,850		—		—		118,924		54,155		1999	2000	(1)
140 Kendrick Street	Office	Needham, MA	—		18,095		66,905		33,823		18,095		100,728		—		—		118,823		39,039		2000	2004	(1)
Shady Grove Innovation District	Office	Rockville, MD	—		52,030		64,212		2,676		26,834		34,974		57,110		—		118,918		1,048		1968-1985	2021	(1)
Weston Corporate Center	Office	Weston, MA	—		25,753		92,312		32		25,854		92,243		—		—		118,097		35,329		2010	2001	(1)


Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2021 (dollars in thousands)
				Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances	Land	Building
17Fifty Presidents Street	Office	Reston, VA	—	—	113,362	44	—	113,406	—	—	113,406	7,840	2020	2013	(1)
Discovery Square	Office	Reston, VA	—	11,198	71,782	15,759	11,146	87,593	—	—	98,739	48,686	2001	2003	(1)
355 Main Street	Office	Cambridge, MA	—	18,863	53,346	24,697	21,098	75,808	—	—	96,906	31,739	1981/1996/2013	2006	(1)
10 CityPoint	Office	Waltham, MA	—	1,953	85,752	6,800	2,127	92,378	—	—	94,505	17,327	2016	1997	(1)
Two Freedom Square	Office	Reston, VA	—	13,930	77,739	(6,396)	13,866	71,407	—	—	85,273	31,823	2001	2003	(1)
90 Broadway	Office	Cambridge, MA	—	19,104	52,078	18,697	20,741	69,138	—	—	89,879	26,749	1983/1998/2013	2006	(1)
153 & 211 Second Avenue	Office	Waltham, MA	—	33,233	55,940	—	33,233	55,940	—	—	89,173	1,819	1964-2006	2021	(1)
230 CityPoint	Office	Waltham, MA	—	13,189	49,823	22,257	13,403	71,866	—	—	85,269	34,984	1992	2005	(1)
77 CityPoint	Office	Waltham, MA	—	13,847	60,383	11,419	13,997	71,652	—	—	85,649	31,804	2008	2001	(1)
20 CityPoint	Office	Waltham, MA	—	4,887	72,764	7,071	4,887	79,835	—	—	84,722	6,135	2020	2007	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—	10,385	60,694	9,675	10,350	70,404	—	—	80,754	39,353	2003	1999	(1)
200 West Street	Office	Waltham, MA	—	16,148	24,983	36,931	16,148	61,597	317	—	78,062	18,922	1999/2021	1997	(1)
Sumner Square	Office	Washington, DC	—	624	28,745	47,265	28,028	48,606	—	—	76,634	29,247	1985	1999	(1)
2440 West El Camino Real	Office	Mountain View, CA	—	16,741	51,285	6,290	16,741	57,575	—	—	74,316	17,265	1987/2003	2011	(1)
300 Binney Street	Office	Cambridge, MA	—	18,080	51,262	140	18,080	51,402	—	—	69,482	14,537	2013	2009	(1)
Reston Corporate Center	Office	Reston, VA	—	9,135	50,857	3,625	9,496	54,121	—	—	63,617	32,162	1984	1998	(1)
Wisconsin Place	Office	Chevy Chase, MD	—	—	53,349	12,600	—	65,949	—	—	65,949	28,025	2009	2004	(1)
255 Main Street	Office	Cambridge, MA	—	134	25,110	32,604	134	57,714	—	—	57,848	39,294	1987	1997	(1)
University Place	Office	Cambridge, MA	—	—	37,091	15,062	6,004	46,149	—	—	52,153	32,504	1985	1998	(1)
890 Winter Street	Office	Waltham, MA	—	13,913	28,557	4,745	13,913	33,302	—	—	47,215	3,928	1999	2019	(1)
Capital Gallery	Office	Washington, DC	—	4,725	29,565	5,018	6,128	33,180	—	—	39,308	20,706	1981/2006	2007	(1)
North First Business Park	Office	San Jose, CA	—	23,398	13,069	4,522	23,371	17,618	—	—	40,989	17,011	1981	2007	(1)
150 Broadway	Office	Cambridge, MA	—	850	25,042	345	822	25,415	—	—	26,237	14,225	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—	1,299	12,943	10,617	1,868	22,991	—	—	24,859	13,674	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—	998	1,426	17,818	1,073	18,978	191	—	20,242	15,785	1982	1997	(1)
The Point	Office	Waltham, MA	—	6,395	10,040	421	6,492	10,364	—	—	16,856	1,984	2015	2007	(1)
690 Folsom Street	Office	San Francisco, CA	—	3,219	11,038	1,877	3,219	12,915	—	—	16,134	3,354	2015	2012	(1)
195 West Street	Office	Waltham, MA	—	1,611	6,652	6,481	1,611	13,133	—	—	14,744	8,540	1990	1997	(1)
33 Hayden Avenue	Office	Lexington, MA	—	266	3,234	10,864	266	14,098	—	—	14,364	6,576	1979	1997	(1)
92-100 Hayden Avenue	Office	Lexington, MA	—	594	6,748	5,530	619	12,253	—	—	12,872	11,247	1985	1997	(1)
7501 Boston Boulevard, Building Seven	Office	Springfield, VA	—	665	9,273	314	665	9,587	—	—	10,252	5,783	1997	1997	(1)
7435 Boston Boulevard, Building One	Office	Springfield, VA	—	392	3,822	4,323	486	8,051	—	—	8,537	6,802	1982	1997	(1)
32 Hartwell Avenue	Office	Lexington, MA	—	168	1,943	6,358	168	8,301	—	—	8,469	2,557	1968/1979/1987	1997	(1)
7450 Boston Boulevard, Building Three	Office	Springfield, VA	—	1,165	4,681	2,199	1,327	6,718	—	—	8,045	4,646	1987	1998	(1)
250 Binney Street	Office	Cambridge, MA	—	110	4,483	2,939	110	7,422	—	—	7,532	6,399	1983	1997	(1)


Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2021 (dollars in thousands)
				Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances	Land	Building
8000 Grainger Court, Building Five	Office	Springfield, VA	—	366	4,282	2,604	453	6,799	—	—	7,252	5,916	1984	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—	5,477	1,090	676	5,477	1,766	—	—	7,243	924	1977	2012	(1)
7300 Boston Boulevard, Building Thirteen	Office	Springfield, VA	—	608	4,773	863	608	5,636	—	—	6,244	2,463	2002	1997	(1)
17 Hartwell Avenue	Office	Lexington, MA	—	26	150	5,921	26	6,071	—	—	6,097	2,961	1968	1997	(1)
7601 Boston Boulevard, Building Eight	Office	Springfield, VA	—	200	878	4,352	378	5,052	—	—	5,430	4,778	1986	1997	(1)
7500 Boston Boulevard, Building Six	Office	Springfield, VA	—	138	3,749	1,181	234	4,834	—	—	5,068	4,376	1985	1997	(1)
8000 Corporate Court, Building Eleven	Office	Springfield, VA	—	136	3,071	1,552	686	4,073	—	—	4,759	3,346	1989	1997	(1)
7375 Boston Boulevard, Building Ten	Office	Springfield, VA	—	23	2,685	824	47	3,485	—	—	3,532	2,790	1988	1997	(1)
7451 Boston Boulevard, Building Two	Office	Springfield, VA	—	249	1,542	1,545	535	2,801	—	—	3,336	2,711	1982	1997	(1)
7374 Boston Boulevard, Building Four	Office	Springfield, VA	—	241	1,605	1,281	303	2,824	—	—	3,127	2,675	1984	1997	(1)
The Skylyne	Residential	Oakland, CA	—	28,962	239,077	1,097	28,962	240,174	—	—	269,136	8,132	2020	N/A	(1)
Signature at Reston	Residential	Reston, VA	—	27,076	190,580	838	27,076	191,418	—	—	218,494	18,534	2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—	9,243	127,248	3,336	9,245	130,582	—	—	139,827	11,195	2018	2015	(1)
The Avant at Reston Town Center	Residential	Reston, VA	—	20,350	91,995	846	20,350	92,841	—	—	113,191	19,681	2014	2010	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—	3,529	54,891	2,215	3,529	57,106	—	—	60,635	15,689	2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—	478	37,918	32,226	478	70,144	—	—	70,622	50,729	1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—	—	35,035	6,432	—	41,467	—	—	41,467	15,695	1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—	1,256	15,697	840	1,256	16,537	—	—	17,793	6,727	2006	2004	(1)
Kendall Center Blue Garage	Garage	Cambridge, MA	—	1,163	11,633	446	1,163	12,079	—	—	13,242	9,900	1990	1997	(1)
Reston Next	Development	Reston, VA	—	—	—	514,182	2,901	250,135	—	261,146	514,182	1,631	N/A	1998	N/A
2100 Pennsylvania Avenue	Development	Washington, DC	—	—	—	393,094	185,203	—	—	207,891	393,094	5,941	N/A	N/A	N/A
325 Main Street	Development	Cambridge, MA	—	174	—	285,807	772	—	—	285,209	285,981	—	N/A	1997	N/A
880 Winter Street	Development	Waltham, MA	—	15,597	37,255	(667)	15,597	19,614	—	16,974	52,185	1,247	1998	2019	N/A
180 CityPoint	Development	Waltham, MA	—	—	—	50,776	—	—	—	50,776	50,776	—	N/A	2006	N/A
103 CityPoint	Development	Waltham, MA	—	—	—	14,663	—	—	—	14,663	14,663	—	N/A	2007	N/A
777 Harrison Street	Land	San Francisco, CA	—	144,647	—	26,800	—	47	171,400	—	171,447	11	N/A	2020	N/A
3625-3635 Peterson Way	Land	Santa Clara, CA	—	63,206	—	4,541	—	—	67,747	—	67,747	—	N/A	2016	N/A
Back Bay Station Master Plan	Land	Boston, MA	—	—	—	53,432	—	—	53,432	—	53,432	—	N/A	N/A	N/A
North First Master Plan	Land	San Jose, CA	—	35,004	—	3,941	—	—	38,945	—	38,945	—	N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—	—	—	37,418	—	—	37,418	—	37,418	—	N/A	2006	N/A
Reston Gateway Master Plan	Land	Reston, VA	—	—	—	30,945	—	—	30,945	—	30,945	—	N/A	1998	N/A
Springfield Metro Center	Land	Springfield, VA	—	—	—	19,887	—	—	19,887	—	19,887	—	N/A	2007	N/A


Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2021 (dollars in thousands)
						Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements			Building and Improvements			Land Held for Development			Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/ Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances			Land		Building
CityPoint South Master Plan	Land	Waltham, MA	—			—		—		14,890		—			—			14,890			—		14,890		—		N/A	N/A	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—			—		—		8,381		—			—			8,381			—		8,381		—		N/A	1997	N/A
Broad Run Business Park	Land	Loudoun County, VA	—			—		—		2,405		—			—			2,405			—		2,405		—		N/A	1998	N/A
Weston Quarry	Land	Weston, MA	—			—		—		1,249		—			—			1,249			—		1,249		—		N/A	2001	N/A
Reston Overlook Master Plan	Land	Reston, VA	—			—		—		79		—			—			79			—		79		—		N/A	2000	N/A

			$	3,267,914	(2)	$	5,238,614	$	13,216,859	$	5,279,360	$	5,348,929	(3)	$	16,931,377	(4)	$	560,355	(5)	$	894,172	$	23,734,833	$	5,736,240

The aggregate cost and accumulated depreciation for tax purposes was approximately $24.2 billion and $5.4 billion, respectively.

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

(2)Includes unamortized deferred financing costs totaling approximately $(32.1) million.

(3)Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $214,165 and $169,778, respectively.

(4)Includes Right of Use Assets - Finance Leases of approximately $23,342.

(5)Includes pre-development costs.

Boston Properties Limited Partnership

Real Estate and Accumulated Depreciation

December 31, 2021, 2020 and 2019

(dollars in thousands)

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


	2021		2020		2019
Real Estate:
Balance at the beginning of the year	$	22,926,494	$	22,449,476	$	21,207,189
Additions to/improvements of real estate	1,145,084		996,989		1,671,898
Assets sold/written-off	(336,745)		(519,971)		(429,611)
Balance at the end of the year	$	23,734,833	$	22,926,494	$	22,449,476
Accumulated Depreciation:
Balance at the beginning of the year	$	5,396,111	$	5,135,289	$	4,773,800
Depreciation expense	615,553		566,813		557,130
Assets sold/written-off	(275,424)		(305,991)		(195,641)
Balance at the end of the year	$	5,736,240	$	5,396,111	$	5,135,289

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

Comprehensive Text Block List (Policies)	12 Months Ended
Comprehensive Text Block List (Policies)	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements are presented using the accrual basis of accounting in conformity with accounting principles generally accepted in the United States of America. Boston Properties, Inc. does not have any other significant assets, liabilities or operations, other than its investment in Boston Properties Limited Partnership, nor does it have employees of its own. Boston Properties Limited Partnership, not Boston Properties, Inc., generally executes all significant business relationships other than transactions involving securities of Boston Properties, Inc. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income.
Consolidation, Variable Interest Entity, Policy	Variable Interest Entities (VIEs)Consolidated VIEs are those for which the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE.

Summary Of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2021

Accounting Policies [Abstract]

Real Estate

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



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

Cash and Cash Equivalents

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

Cash Held in Escrows

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

Investment in Securities

Investments in Securities The Company accounts for investments in equity securities at fair value, with gains or losses resulting from changes in fair value recognized currently in earnings. The Company maintains deferred compensation plans that are designed to allow officers and non-employee directors of Boston Properties, Inc. to defer a portion of the officer’s current income or the non-employee director’s current compensation on a pre-tax basis and receive a tax-deferred return on these deferrals based on the performance of specific investments selected by the officer or non-employee director. The Company’s obligation under the plans is that of an unsecured promise to pay the deferred compensation to the plan participants in the future.

Tenant and Other Receivables and Notes Receivable

Tenant and Other Receivables

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

Notes Receivable

Deferred Charges

Investments in Unconsolidated Joint Ventures

Revenue Recognition


	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2022	$	428	$	7,119
2023	208		5,334
2024	147		3,806
2025	135		3,775
2026	135		2,843

Lessee, Leases

Lessee

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

•unlevered property yields and discount rates.

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

Lessor, Leases

Lessor

Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized as revenue in the period during which the expenses are incurred. The Company recognizes these reimbursements on a gross basis, as the Company obtains control of the goods and services before they are transferred to the tenant.

In addition, in accordance with ASC 842, lessors will only capitalize incremental direct leasing costs.

Earnings Per Share and Earnings Per Common Unit

Earnings Per Share

Earnings Per Common Unit

Recurring Fair Value of Financial Instruments

Fair Value of Financial Instruments


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			Level 3
Unsecured term loan (2)			Level 3

_______________

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

(2) As of December 31, 2021, the unsecured term loan had been repaid and was no longer outstanding.


	December 31, 2021				December 31, 2020
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable, net	$	78,336	$	82,867	$	77,552	$	84,579
Note receivable, net	9,641		10,000		18,729		19,372
Total	$	87,977	$	92,867	$	96,281	$	103,951

Mortgage notes payable, net	$	3,267,914	$	3,395,569	$	2,909,081	$	3,144,150
Unsecured senior notes, net	9,483,695		9,966,591		9,639,287		10,620,527
Unsecured line of credit	145,000		145,317		—		—
Unsecured term loan, net	—		—		499,390		500,326
Total	$	12,896,609	$	13,507,477	$	13,047,758	$	14,265,003

Derivative Instruments and Hedging Activities

Stock-Based Employee Compensation Plans

Stock-Based Employee Compensation PlansAt December 31, 2021, the Company had a stock-based employee compensation plan. The Company accounts for the plan under the guidance in ASC 718 “Compensation – Stock Compensation” (“ASC 718”), which revised the fair value based method of accounting for share-based payment liabilities, forfeitures and modifications of stock-based awards and clarified previous guidance in several areas, including measuring fair value, classifying an award as equity or as a liability and attributing compensation cost to reporting periods.

Reclassification

Certain prior year amounts have been reclassified to conform to the current year presentation.

Use of Estimates in the Preparation of Financial Statements

Equity Offering Costs

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

Treasury Stock

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

Dividends

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

Income Taxes

Boston Properties Limited Partnership

Income Taxes

Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2021

Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment

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



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

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

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


	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2022	$	428	$	7,119
2023	208		5,334
2024	147		3,806
2025	135		3,775
2026	135		2,843

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

Recurring Fair Value of Financial Instruments


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			Level 3
Unsecured term loan (2)			Level 3

_______________

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

(2) As of December 31, 2021, the unsecured term loan had been repaid and was no longer outstanding.

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


	December 31, 2021				December 31, 2020
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable, net	$	78,336	$	82,867	$	77,552	$	84,579
Note receivable, net	9,641		10,000		18,729		19,372
Total	$	87,977	$	92,867	$	96,281	$	103,951

Mortgage notes payable, net	$	3,267,914	$	3,395,569	$	2,909,081	$	3,144,150
Unsecured senior notes, net	9,483,695		9,966,591		9,639,287		10,620,527
Unsecured line of credit	145,000		145,317		—		—
Unsecured term loan, net	—		—		499,390		500,326
Total	$	12,896,609	$	13,507,477	$	13,047,758	$	14,265,003

Dividends Declared


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
December 31, 2021	January 28, 2022	$0.98	$0.98
September 30, 2021	October 29, 2021	$0.98	$0.98
June 30, 2021	July 30, 2021	$0.98	$0.98
March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98
September 30, 2020	October 30, 2020	$0.98	$0.98
June 30, 2020	July 31, 2020	$0.98	$0.98
March 31, 2020	April 30, 2020	$0.98	$0.98
December 31, 2019	January 30, 2020	$0.98	$0.98
September 30, 2019	October 31, 2019	$0.95	$0.95
June 28, 2019	July 31, 2019	$0.95	$0.95
March 29, 2019	April 30, 2019	$0.95	$0.95
December 31, 2018	January 30, 2019	$0.95	$0.95

Dividend Paid [Member]

Summary Of Significant Accounting Policies [Line Items]

Dividends Declared

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


	For the year ended December 31,
	2021					2020					2019
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	2.90		73.86	%	$	2.52		64.91	%	$	2.99		94.84	%
Capital gain income	0.57			14.57	%	0.99			25.49	%	0.16			5.16	%
Return of capital	0.45			11.57	%	0.37			9.60	%	—			—	%
Total	$	3.92	(1)	100.00	%	$	3.88	(2)	100.00	%	$	3.15	(3)	100.00	%

_____________

(1)The fourth quarter 2021 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2022.

(2)The fourth quarter 2020 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2021.

Real Estate (Tables)

12 Months Ended

Dec. 31, 2021

Schedule of Real Estate Properties

Boston Properties Limited Partnership

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


	December 31, 2021		December 31, 2020
Land	$	4,964,986	$	4,971,990
Right of use assets - finance leases	237,507		237,393
Right of use assets - operating leases (1)	169,778		146,406
Land held for future development (2)	560,355		450,954
Buildings and improvements	14,014,010		13,498,098
Tenant improvements	2,894,025		2,752,880
Furniture, fixtures and equipment	51,695		49,606
Construction in progress	894,172		868,773
Total	23,786,528		22,976,100
Less: Accumulated depreciation	(5,772,018)		(5,428,576)
	$	18,014,510	$	17,547,524

_______________

(1)See Note 4.

(2)Includes pre-development costs.

153 & 211 Second Avenue [Member]

Asset Acquisition [Table Text Block]

The following table summarizes the allocation of the purchase price, including transaction costs, of 153 & 211 Second Avenue at the date of acquisition (in thousands):


Land	$	33,233
Building and improvements	53,309
Tenant improvements	2,631
In-place lease intangibles	13,415
Below-market lease intangibles	(2,412)
Net assets acquired	$	100,176

Shady Grove Innovation District [Member]

Asset Acquisition [Table Text Block]

The following table summarizes the allocation of the purchase price, including transaction costs, of Shady Grove Innovation District at the date of acquisition (in thousands):


Land	$	52,030
Building and improvements	63,060
Tenant improvements	1,152
In-place lease intangibles	2,523
Above-market lease intangibles	142
Below-market lease intangibles	(403)
Net assets acquired	$	118,504

360 Park Avenue South

Asset Acquisition [Table Text Block]

The following table summarizes the allocation of the purchase price of 360 Park Avenue South at the date of acquisition (in thousands):


Land	$	215,448
Building and improvements	85,220




Net assets acquired	$	300,668

153 & 211 Second Avenue and Shady Grove Innovation District [Member]

Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination

The following table summarizes the estimated amortization of the acquired in-place lease intangibles

and the acquired above/below-market lease intangibles as of December 31, 2021 for 153 & 211 Second Avenue and Shady Grove Innovation District through the last lease expiration (in thousands):


	Acquired In-Place Lease Intangibles		Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2022	$	9,691	$	74	$	1,713
2023	151		25		39
2024	56		12		26

Leases (Tables)

12 Months Ended

Dec. 31, 2021

Finance Lease, Liability, Maturity

The following table provides lease cost information for the Company’s operating and finance leases for the years ended December 31, 2021, 2020 and 2019 (in thousands):


	Year ended December 31,
Lease costs	2021		2020		2019
Operating lease costs	$	13,151	$	13,948	$	14,573
Finance lease costs
Amortization of right of use asset (1)	$	547	$	56	$	29
Interest on lease liabilities (2)	$	2,471	$	583	$	47

_______________

The following table provides other quantitative information for the Company’s operating and finance leases as of December 31, 2021 and December 31, 2020:


	December 31, 2021		December 31, 2020
Other information
Weighted-average remaining lease term (in years)
Operating leases	50		51
Finance leases	69		70
Weighted-average discount rate
Operating leases	5.7	%	5.7	%
Finance leases	6.2	%	6.2	%

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2021 (in thousands):


	Operating		Finance
2022	$	19,623	$	8,762
2023	25,333		10,826
2024 (1)	10,085		48,605
2025	10,307		9,971
2026	10,100		10,166
Thereafter	538,801		1,363,011
Total lease payments	614,249		1,451,341
Less: Interest portion	(409,688)		(1,206,920)
Present value of lease payments	$	204,561	$	244,421

_______________

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

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2020 (in thousands):


	Operating		Finance
2021	$	25,092	$	5,896
2022	18,020		10,206
2023	10,262		9,701
2024 (1)	9,277		48,518
2025	9,476		9,971
Thereafter	548,478		1,373,177
Total lease payments	620,605		1,457,469
Less: Interest portion	(418,892)		(1,220,977)
Present value of lease payments	$	201,713	$	236,492

_______________

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

Lessor, Lease, Description [Line Items]

Operating Lease, Lease Income [Table Text Block]

Lessor


	Year ended December 31,
Lease Revenue	2021		2020		2019
Fixed contractual payments	$	2,319,362	$	2,211,915	$	2,261,260
Variable lease payments	433,652		434,346		496,754
	$	2,753,014	$	2,646,261	$	2,758,014

Lessor, Operating Lease, Payments to be Received, Maturity


Years Ending December 31,
2022	$	2,252,034
2023	2,251,287
2024	2,138,772
2025	2,012,975
2026	1,877,563
Thereafter	12,215,114

Sumner Square

Lessee, Operating Lease, Liability, Maturity

The following table provides a maturity analysis for the Company’s lease liabilities related to its Sumner Square operating lease as of May 19, 2021 (in thousands):


	Operating
Period from May 19, 2021 through December 31, 2021	$	23,599
2022	761
2023	784
2024	808
2025	832
2026	422
Total lease payments	27,206
Less: Interest portion	(536)
Present value of lease payments	$	26,670

Deferred Charges (Tables)

12 Months Ended

Dec. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

Deferred Costs

Deferred charges consisted of the following at December 31, 2021 and 2020 (in thousands):


	December 31, 2021		December 31, 2020
Leasing costs, including lease related intangibles	$	1,011,229	$	1,023,058
Financing costs	19,231		12,728
	1,030,460		1,035,786
Less: Accumulated amortization	(411,662)		(395,701)
	$	618,798	$	640,085

Finite-lived Intangible Assets Amortization Expense

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


	Acquired In-Place Lease Intangibles
2022	$	13,827
2023	3,911
2024	2,200
2025	2,112
2026	1,624

Investments in Unconsolidated Joint Ventures (Tables)

12 Months Ended

Sep. 01, 2021

Dec. 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 December 31, 2021 and December 31, 2020:


					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			December 31, 2021		December 31, 2020
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.00	%		$	(1,205)	$	(3,766)
BP/CRF Metropolitan Square LLC	Metropolitan Square	20.00	%		(15,356)		(13,584)
901 New York, LLC	901 New York Avenue	25.00	%	(2)	(12,597)		(12,264)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.33	%	(3)	33,732		35,297
Annapolis Junction NFM LLC	Annapolis Junction	50.00	%	(4)	N/A		13,463
540 Madison Venture LLC	540 Madison Avenue	60.00	%	(5)	N/A		122
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.00	%		(7,913)		(6,945)
501 K Street LLC	1001 6th Street	50.00	%	(6)	42,576		42,499
Podium Developer LLC	The Hub on Causeway - Podium	50.00	%		48,980		48,818
Residential Tower Developer LLC	Hub50House	50.00	%		47,774		50,943
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.00	%		11,505		10,754
Office Tower Developer LLC	100 Causeway Street	50.00	%		57,687		56,312
1265 Main Office JV LLC	1265 Main Street	50.00	%		3,541		3,787
BNY Tower Holdings LLC	Dock 72	50.00	%		27,343		29,536
BNYTA Amenity Operator LLC	Dock 72	50.00	%		1,069		1,846
CA-Colorado Center Limited Partnership	Colorado Center	50.00	%		231,479		227,671
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.00	%		61,626		58,112
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.00	%		116,306		113,774
SMBP Venture LP	Santa Monica Business Park	55.00	%		156,639		145,761
Platform 16 Holdings LP	Platform 16	55.00	%	(7)	109,086		108,393
Gateway Portfolio Holdings LLC	Gateway Commons	50.00	%	(8)	327,148		336,206
Rosecrans-Sepulveda Partners 4, LLC	Beach Cities Media Campus	50.00	%		27,106		27,184
Safeco Plaza REIT LLC	Safeco Plaza	33.67	%	(9)	72,545		N/A
360 PAS Holdco LLC	360 Park Avenue South	42.21	%	(10)	106,855		N/A
					$	1,445,926	$	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.

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

(8)As a result of the partner’s deferred contribution, the Company owned an approximately 50% and 55% interest in the joint venture at December 31, 2021 and December 31, 2020, respectively.

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

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


	December 31, 2021		December 31, 2020
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	5,579,218	$	4,708,571
Other assets	586,470		531,071
Total assets	$	6,165,688	$	5,239,642
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	3,214,961	$	2,637,911
Other liabilities (2)	652,135		650,433
Members’/Partners’ equity	2,298,592		1,951,298
Total liabilities and members’/partners’ equity	$	6,165,688	$	5,239,642
Company’s share of equity	$	1,104,175	$	936,087
Basis differentials (3)	341,751		337,832
Carrying value of the Company’s investments in unconsolidated joint ventures (4)	$	1,445,926	$	1,273,919

_______________


	December 31, 2021		December 31, 2020
Property	(in thousands)
Colorado Center	$	304,776	$	307,328
Gateway Commons	51,009		51,875
Dock 72	(50,051)		(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:


	Year ended December 31,
		2021		2020		2019
		(in thousands)
Total revenue (1)		$	383,649	$	319,560	$	322,817
Expenses
Operating		158,498		144,347		122,992
Transaction costs		470		1,027		1,000
Depreciation and amortization		147,121		141,853		102,296
Total expenses		306,089		287,227		226,288
Other income (expense)
Interest expense		(108,884)		(98,051)		(84,409)
Gains on sales of real estate (2)		—		11,737		32,706
Net income (loss)		$	(31,324)	$	(53,981)	$	44,826

Company’s share of net income (loss)		$	(10,254)	$	(16,256)	$	24,423
Gain on sale of investment (3)		10,257		—		—
Impairment loss on investment (4)		—		(60,524)		—
Basis differential (2)(4)(5)		(2,573)		(8,330)		22,169
Income (loss) from unconsolidated joint ventures		$	(2,570)	$	(85,110)	$	46,592

_______________

(1)Includes straight-line rent adjustments of approximately $17.2 million, $(10.1) million and $32.4 million for the years ended December 31, 2021, 2020 and 2019, respectively.

Safeco Plaza

Schedule of Equity Method Investments [Line Items]

Schedule of Business Acquisitions, by Acquisition

The following table summarizes the allocation of the purchase price, including transaction costs, of Safeco Plaza joint venture at the date of acquisition (in thousands):


Land	$	81,343
Building and improvements	351,948
Tenant improvements	30,404
In-place lease intangibles	28,658
Above-market lease intangibles	301
Below-market lease intangibles	(32,542)
Net assets acquired	$	460,112

Safeco Plaza REIT LLC | Safeco Plaza

Schedule of Equity Method Investments [Line Items]

Schedule of Finite-Lived Intangible Assets Acquired as Part of Business Combination


	Acquired In-Place Lease Intangibles		Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2022	$	4,278	$	49	$	4,663
2023	3,453		49		4,596
2024	3,036		49		4,383
2025	2,851		49		4,337
2026	2,749		42		4,329

Mortgage Notes Payable, Net (Tables)

12 Months Ended

Dec. 31, 2021

Mortgage Notes Payable [Abstract]

Schedule Of Aggregate Principal Payments On Mortgage Notes

Contractual aggregate principal payments of mortgage notes payable at December 31, 2021 are as follows (in thousands):


	Principal Payments
2022	$	—
2023	—
2024	—
2025	—
2026	—
Thereafter	3,300,000
Total aggregate principal payments	3,300,000
Deferred financing costs, net	(32,086)
Total carrying value of mortgage notes payable, net	$	3,267,914

Unsecured Senior Notes (Tables)

12 Months Ended

Dec. 31, 2021

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

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


	Coupon/Stated Rate		Effective Rate(1)		Principal Amount		Maturity Date(2)
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
12 Year Unsecured Senior Notes	2.450	%	2.524	%	850,000		October 1, 2033
Total principal					9,550,000
Less:
Net unamortized discount					16,548
Deferred financing costs, net					49,757
Total					$	9,483,695

_______________

(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.

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.

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Noncontrolling Interest [Line Items]

Noncontrolling Interests (Tables)

12 Months Ended

Dec. 31, 2021

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


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
December 31, 2021	January 28, 2022	$0.98	$0.98
September 30, 2021	October 29, 2021	$0.98	$0.98
June 30, 2021	July 30, 2021	$0.98	$0.98
March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98
September 30, 2020	October 30, 2020	$0.98	$0.98
June 30, 2020	July 31, 2020	$0.98	$0.98
March 31, 2020	April 30, 2020	$0.98	$0.98
December 31, 2019	January 30, 2020	$0.98	$0.98
September 30, 2019	October 31, 2019	$0.95	$0.95
June 28, 2019	July 31, 2019	$0.95	$0.95
March 29, 2019	April 30, 2019	$0.95	$0.95
December 31, 2018	January 30, 2019	$0.95	$0.95

Noncontrolling Interests [Member]

Noncontrolling Interest [Line Items]

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


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 31, 2021	January 28, 2022	$0.98	$0.098
September 30, 2021	October 29, 2021	$0.98	$0.098
June 30, 2021	July 30, 2021	$0.98	$0.098
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
December 31, 2020	January 28, 2021	$0.98	$0.098
September 30, 2020	October 30, 2020	$0.98	$0.098
June 30, 2020	July 31, 2020	$0.98	$0.098
March 31, 2020	April 30, 2020	$0.98	$0.098
December 31, 2019	January 30, 2020	$0.98	$0.098


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

Stockholders' Equity / Partners' Capital (Tables)

12 Months Ended

Dec. 31, 2021

Class of Stock [Line Items]

Dividends Declared [Table Text Block]


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
December 31, 2021	January 28, 2022	$0.98	$0.98
September 30, 2021	October 29, 2021	$0.98	$0.98
June 30, 2021	July 30, 2021	$0.98	$0.98
March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98
September 30, 2020	October 30, 2020	$0.98	$0.98
June 30, 2020	July 31, 2020	$0.98	$0.98
March 31, 2020	April 30, 2020	$0.98	$0.98
December 31, 2019	January 30, 2020	$0.98	$0.98
September 30, 2019	October 31, 2019	$0.95	$0.95
June 28, 2019	July 31, 2019	$0.95	$0.95
March 29, 2019	April 30, 2019	$0.95	$0.95
December 31, 2018	January 30, 2019	$0.95	$0.95

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 Series B Preferred Stock paid or declared during the years ended December 31, 2021, 2020 and 2019:

Record Date

Payment Date

Dividend (Per Share)

February 5, 2021

February 16, 2021

$32.8125

November 4, 2020

November 16, 2020

$32.8125

August 3, 2020

August 17, 2020

$32.8125

May 1, 2020

May 15, 2020

$32.8125

February 4, 2020

February 18, 2020

$32.8125

November 1, 2019

November 15, 2019

$32.8125

August 2, 2019

August 15, 2019

$32.8125

May 3, 2019

May 15, 2019

$32.8125

February 4, 2019

February 15, 2019

$32.8125

Segment Information (Tables)

12 Months Ended

Dec. 31, 2021

Segment Reporting [Abstract]

Schedule Of Reconciliation Of Net Operating Income To Net Income

Boston Properties, Inc.


	Year ended December 31,
		2021		2020		2019
		(in thousands)
Net income attributable to Boston Properties, Inc. common shareholders		$	496,223	$	862,227	$	511,034
Add:
Preferred stock redemption charge		6,412		—		—
Preferred dividends		2,560		10,500		10,500
Noncontrolling interest—common units of the Operating Partnership		55,931		97,704		59,345
Noncontrolling interests in property partnerships		70,806		48,260		71,120
Interest expense		423,346		431,717		412,717
Losses from early extinguishment of debt		45,182		—		29,540
Impairment loss		—		—		24,038
Net operating income from unconsolidated joint ventures		107,756		94,943		97,716
Depreciation and amortization expense		717,336		683,751		677,764
Transaction costs		5,036		1,531		1,984
Payroll and related costs from management services contracts		12,487		11,626		10,386
General and administrative expense		151,573		133,112		140,777
Less:
Net operating income attributable to noncontrolling interests in property partnerships		186,304		162,887		183,989
Gains from investments in securities		5,626		5,261		6,417
Interest and other income (loss)		5,704		5,953		18,939
Gains on sales of real estate		123,660		618,982		709
Income (loss) from unconsolidated joint ventures		(2,570)		(85,110)		46,592
Direct reimbursements of payroll and related costs from management services contracts		12,487		11,626		10,386
Development and management services revenue		27,697		29,641		40,039
Company’s share of Net Operating Income		$	1,735,740	$	1,626,131	$	1,739,850

Boston Properties Limited Partnership


	Year ended December 31,
		2021		2020		2019
		(in thousands)
Net income attributable to Boston Properties Limited Partnership common unitholders		$	561,993	$	979,979	$	580,102
Add:
Preferred unit redemption charge		6,412		—		—
Preferred distributions		2,560		10,500		10,500
Noncontrolling interests in property partnerships		70,806		48,260		71,120
Interest expense		423,346		431,717		412,717
Losses from early extinguishment of debt		45,182		—		29,540
Impairment loss		—		—		22,272
Net operating income from unconsolidated joint ventures		107,756		94,943		97,716
Depreciation and amortization expense		709,035		676,666		669,956
Transaction costs		5,036		1,531		1,984
Payroll and related costs from management services contracts		12,487		11,626		10,386
General and administrative expense		151,573		133,112		140,777
Less:
Net operating income attributable to noncontrolling interests in property partnerships		186,304		162,887		183,989
Gains from investments in securities		5,626		5,261		6,417
Interest and other income (loss)		5,704		5,953		18,939
Gains on sales of real estate		125,198		631,945		858
Income (loss) from unconsolidated joint ventures		(2,570)		(85,110)		46,592
Direct reimbursements of payroll and related costs from management services contracts		12,487		11,626		10,386
Development and management services revenue		27,697		29,641		40,039
Company’s share of Net Operating Income		$	1,735,740	$	1,626,131	$	1,739,850

Schedule Of Segment Information By Geographic Area And Property Type

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

For the year ended December 31, 2021:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Office	$	930,560		$	—		$	1,012,172		$	508,620		$	—		$	340,808		$	2,792,160
Residential	13,397			—			—			3,892			—			25,379			42,668
Hotel	13,609			—			—			—			—			—			13,609
Total	957,566			—			1,012,172			512,512			—			366,187			2,848,437
% of Grand Totals	33.62		%	—		%	35.53		%	17.99		%	—		%	12.86		%	100.00		%
Rental Expenses:
Office	322,298			—			379,267			168,040			—			127,102			996,707
Residential	5,811			—			—			6,717			—			11,916			24,444
Hotel	12,998			—			—			—			—			—			12,998
Total	341,107			—			379,267			174,757			—			139,018			1,034,149
% of Grand Totals	32.98		%	—		%	36.67		%	16.90		%	—		%	13.45		%	100.00		%
Net operating income	$	616,459		$	—		$	632,905		$	337,755		$	—		$	227,169		$	1,814,288
% of Grand Totals	33.98		%	—		%	34.88		%	18.62		%	—		%	12.52		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(43,232)			—			(143,072)			—			—			—			(186,304)
Add: Company’s share of net operating income from unconsolidated joint ventures	16,551			51,641			(664)			14,152			2,498			23,578			107,756
Company’s share of net operating income	$	589,778		$	51,641		$	489,169		$	351,907		$	2,498		$	250,747		$	1,735,740
% of Grand Totals	33.98		%	2.98		%	28.18		%	20.27		%	0.14		%	14.45		%	100.00		%

_______________

For the year ended December 31, 2020:


	Boston			Los Angeles			New York			San Francisco			Washington, DC			Total
Rental Revenue: (1)
Office	$	897,915		$	—		$	935,966		$	508,327		$	336,587		$	2,678,795
Residential	13,616			—			—			155			24,375			38,146
Hotel	7,478			—			—			—			—			7,478
Total	919,009			—			935,966			508,482			360,962			2,724,419
% of Grand Totals	33.73		%	—		%	34.36		%	18.66		%	13.25		%	100.00		%
Rental Expenses:
Office	318,509			—			384,753			163,156			132,051			998,469
Residential	5,378			—			—			2,261			11,100			18,739
Hotel	13,136			—			—			—			—			13,136
Total	337,023			—			384,753			165,417			143,151			1,030,344
% of Grand Totals	32.71		%	—		%	37.35		%	16.05		%	13.89		%	100.00		%
Net operating income	$	581,986		$	—		$	551,213		$	343,065		$	217,811		$	1,694,075
% of Grand Totals	34.35		%	—		%	32.54		%	20.25		%	12.86		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(41,849)			—			(121,038)			—			—			(162,887)
Add: Company’s share of net operating income from unconsolidated joint ventures	10,765			57,907			(5,326)			14,928			16,669			94,943
Company’s share of net operating income	$	550,902		$	57,907		$	424,849		$	357,993		$	234,480		$	1,626,131
% of Grand Totals	33.88		%	3.56		%	26.12		%	22.02		%	14.42		%	100.00		%

_______________

For the year ended December 31, 2019:


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

_______________

Stock Option and Incentive Plan (Tables)

12 Months Ended

Dec. 31, 2021

Text Block [Abstract]

Share-based Payment Arrangement, Option, Activity

A summary of the status of Boston Properties, Inc.’s stock options as of December 31, 2021, 2020 and 2019 and changes during the years then ended are presented below:


	Shares	Weighted-Average Exercise Price
Outstanding at December 31, 2018	540,441	$	96.35
Exercised	(145,088)	$	96.27
Outstanding at December 31, 2019	395,353	$	96.37
Exercised	(43,792)	$	91.60
Outstanding at December 31, 2020	351,561	$	96.97
Exercised	(247,920)	$	96.95
Outstanding at December 31, 2021	103,641	$	97.01

Schedule of Stock Options Outstanding

The following table summarizes information about Boston Properties, Inc.’s stock options outstanding at December 31, 2021:


Options Outstanding				Options Exercisable
Number Outstanding at 12/31/21	Weighted-Average Remaining Contractual Life	Exercise Price		Number Exercisable at 12/31/21	Exercise Price
54,282	1.3 years	$	95.69	54,282	$	95.69
49,359	1.1 years	$	98.46	49,359	$	98.46

Organization (Details) $ in Thousands, ft² in Millions			12 Months Ended
Organization (Details) $ in Thousands, ft² in Millions	Apr. 01, 2021 shares	Mar. 02, 2021 shares	Dec. 31, 2021 USD ($) ft² Real_Estate_Properties yr shares	Dec. 31, 2020 USD ($) shares	Mar. 31, 2021 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Real Estate Properties [Line Items]
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 \| $			$ 48,466	$ 50,587		$ 46,936	$ 95,832
Dividends and distributions payable \| $			$ 169,859	$ 171,082		$ 170,713
Boston Properties Limited Partnership
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)			89.70%	90.00%
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties \| Real_Estate_Properties			201
Net Rentable Area (in sf) \| ft²			52.8
Total Properties Under Construction [ Member]
Real Estate Properties [Line Items]
Number of real estate properties \| Real_Estate_Properties			9
Net Rentable Area (in sf) \| ft²			3.4
Total Office Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties \| Real_Estate_Properties			182
Office Properties Under Construction [Member]
Real Estate Properties [Line Items]
Number of real estate properties \| Real_Estate_Properties			9
Retail Properties [ Member]
Real Estate Properties [Line Items]
Number of real estate properties \| Real_Estate_Properties			12
Residential Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties \| Real_Estate_Properties			6
Hotel Property [ Member]
Real Estate Properties [Line Items]
Number of real estate properties \| Real_Estate_Properties			1
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Real Estate Properties [Line Items]
Preferred Stock, Dividend Rate, Percentage		5.25%		5.25%
Preferred stock / units, shares / units outstanding (in shares / units) \| shares		80,000		80,000
Preferred Stock, Redemption Date	Apr. 01, 2021
OP Units for redemption (in shares) \| shares	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
OP Units for redemption (in shares) \| 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

Variable Interest Entities (Details)	Dec. 31, 2021
Variable Interest Entity [Line Items]
Number of VIEs	6
Number of VIEs - Total	7
Commercial Real Estate Properties [Member]
Variable Interest Entity [Line Items]
Number of VIEs	5

Summary Of Significant Accounting Policies Schedule of Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2021
Land Improvements \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	25 to 40 years
Land Improvements \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	25 to 40 years
Buildings and improvements \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	10 to 40 years
Buildings and improvements \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	10 to 40 years
Tenant improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3 to 7 years
Furniture, fixtures, and equipment \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3 to 7 years

Schedule of Finite Lived Intagible Assets Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
2023	$ 3,911
2024	2,200
2025	2,112
2026	1,624
Above Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022	428
2023	208
2024	147
2025	135
2026	135
Below Market Lease [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022	7,119
2023	5,334
2024	3,806
2025	3,775
2026	$ 2,843

Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	$ 78,336	$ 77,552
Notes receivable, net	10,000	18,729
Mortgage notes payable, net	3,214,961	2,637,911
Unsecured senior notes, net	9,483,695	9,639,287
Unsecured line of credit	145,000	0
Unsecured term loan, net	0	499,390
Total	3,300,000
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	78,336	77,552
Notes receivable, net	9,641	18,729
Total	87,977	96,281
Mortgage notes payable, net	3,267,914	2,909,081
Unsecured senior notes, net	9,483,695	9,639,287
Unsecured line of credit	145,000	0
Unsecured term loan, net	0	499,390
Total	12,896,609	13,047,758
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	82,867	84,579
Notes receivable, net	10,000	19,372
Total	92,867	103,951
Mortgage notes payable, net	3,395,569	3,144,150
Unsecured senior notes, net	9,966,591	10,620,527
Unsecured line of credit	145,317	0
Unsecured term loan, net	0	500,326
Total	$ 13,507,477	$ 14,265,003

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

12 Months Ended

Dec. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

Dec. 20, 2021

Summary Of Significant Accounting Policies [Line Items]

Dividends Treatment For Federal Tax Purposes, Percentage

$ 3.92

^[1]

$ 3.88

^[2]

$ 3.15

^[3]

100.00%

Summary Of Significant Accounting Policies [Line Items]

$ 0.98

Ordinary income

Dividends Treatment For Federal Tax Purposes, Percentage

$ 2.90

$ 2.52

$ 2.99

73.86%

64.91%

94.84%

Capital Gain Income

Summary Of Significant Accounting Policies [Line Items]

Dividends Treatment For Federal Tax Purposes, Percentage

$ 0.57

$ 0.99

$ 0.16

14.57%

25.49%

5.16%

Return of Capital

Summary Of Significant Accounting Policies [Line Items]

Dividends Treatment For Federal Tax Purposes, Percentage

$ 0.45

$ 0.37

$ 0

11.57%

9.60%

0.00%

Dividend Declared

Summary Of Significant Accounting Policies [Line Items]

Summary Of Significant Accounting Policies [Line Items]

$ 0.98

Allocated to 2019

Summary Of Significant Accounting Policies [Line Items]

0.04

Allocated to 2020

$ 0.94

[1]	The fourth quarter 2021 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2022.
[2]	The fourth quarter 2020 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2021.
[3]	The fourth quarter 2019 regular quarterly dividend was $0.98 per common share of which approximately $0.04 per common share was allocable to 2019 and approximately $0.94 per common share was allocable to 2020.

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

Dec. 31, 2021

Dec. 31, 2020

Land

$ 4,964,986

$ 4,971,990

248,900

Land held for future development

22,300

22,500

^[1]

560,355

450,954

Buildings and improvements

14,014,010

13,498,098

Tenant improvements

2,894,025

2,752,880

Furniture, Fixtures and Equipment

51,695

49,606

Construction in progress

894,172

868,773

Less: accumulated depreciation

23,786,528

22,976,100

(5,772,018)

(5,428,576)

Total real estate

^[2]

$ 5,579,218

$ 4,708,571

[1]	Includes pre-development costs.
[2]	At December 31, 2021 and December 31, 2020, this amount included right of use assets - finance leases totaling approximately $248.9 million. At December 31, 2021 and December 31, 2020, this amount included right of use assets - operating leases totaling approximately $22.3 million and $22.5 million, respectively.

Real Estate (Narrative) (Details)
$ in Thousands

5 Months Ended

7 Months Ended

10 Months Ended

12 Months Ended

Dec. 14, 2021

USD ($)

ft²

Oct. 25, 2021

USD ($)

ft²

Buildings

Aug. 02, 2021

USD ($)

ft²

Buildings

Jun. 02, 2021

USD ($)

ft²

Buildings

Apr. 19, 2021

USD ($)

ft²

Dec. 31, 2021

USD ($)

Dec. 31, 2021

USD ($)

Oct. 24, 2021

USD ($)

Dec. 31, 2021

USD ($)

Dec. 31, 2020

USD ($)

Dec. 31, 2019

USD ($)

Dec. 15, 2021

Dec. 08, 2021

ft²

Dec. 03, 2021

ft²

Oct. 19, 2021

ft²

Apr. 16, 2021

ft²

Feb. 25, 2021

ft²

Feb. 01, 2021

ft²

Assumption of mortgage notes payable

$ 200,311

$ 0

Issuance of operating partnership units for 360 Park Avenue South

99,689

Secured Debt

$ 3,214,961

3,214,961

2,637,911

Proceeds from sales of real estate

^[1]

383,649

319,560

322,817

179,887

519,303

90,824

153 & 211 Second Avenue [Member]

(31,324)

(53,981)

44,826

Payments to Acquire Real Estate

$ 100,200

Number of real estate properties | Buildings

Leased percentage

100.00%

137,000

Shady Grove Innovation District [Member]

5,500

Operating Income (Loss)

$ (2,100)

Payments to Acquire Real Estate

$ 118,500

Number of buildings | Buildings

435,000

Area of Land | a

1,200

Operating Income (Loss)

$ (1,500)

360 Park South Avenue

Noncash or Part Noncash Acquisition, Value of Assets Acquired

450,000

Number of floors

$ 300,700

Assumption of mortgage notes payable

$ 200,300

Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued | shares

866,503

Issuance of operating partnership units for 360 Park Avenue South

$ 99,700

42.21%

Debt - Total loan amount

$ 220,000

11251 Roger Bacon Drive

Leased percentage

100.00%

Asset Acquisition, Price of Acquisition, Expected

65,000

Area of Land | a

2.6

$ 5,600

One Five Nine East 53rd Street

Noncontrolling Interest, Ownership Percentage by Parent

220,000

55.00%

3625 - 3635 Peterson Way

218,000

Reston Next

1,100,000

200 West Street

6595 Springfield Center Drive

138,000

Gains (Losses) on Sales of Investment Real Estate

$ 8,100

181, 191 and 201 Spring Street

Number of real estate properties | Buildings

Proceeds from sales of real estate

333,000

Contractual Sales Price

$ 191,500

179,900

Gains (Losses) on Sales of Investment Real Estate

$ 117,100

Construction in Progress | 180 CityPoint

$ 5,700

$ 7,200

$ 7,000

Construction in Progress | 880 Winter Street [Member]

329,000

Construction in Progress | The Prudential Center Observatory

224,000

Construction in Progress | 103 CityPoint

59,000

113,000

[1]	Includes straight-line rent adjustments of approximately $17.2 million, $(10.1) million and $32.4 million for the years ended December 31, 2021, 2020 and 2019, respectively

Real Estate Asset Acquisition (Details) - USD ($) $ in Thousands	Dec. 14, 2021	Aug. 02, 2021	Jun. 02, 2021
153 & 211 Second Avenue [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Land			$ 33,233
Building and improvements			53,309
Tenant improvements			2,631
Net assets acquired			100,176
153 & 211 Second Avenue [Member] \| In-Place Lease Intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
Lease Intangibles			13,415
153 & 211 Second Avenue [Member] \| Below Market Lease Intangible [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Lease Intangibles			$ (2,412)
Shady Grove Innovation District [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Land		$ 52,030
Building and improvements		63,060
Tenant improvements		1,152
Net assets acquired		118,504
Shady Grove Innovation District [Member] \| In-Place Lease Intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
Lease Intangibles		2,523
Shady Grove Innovation District [Member] \| Above Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Lease Intangibles		142
Shady Grove Innovation District [Member] \| Below Market Lease Intangible [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Lease Intangibles		$ (403)
360 Park Avenue South
Acquired Finite-Lived Intangible Assets [Line Items]
Land	$ 215,448
Building and improvements	85,220
Net assets acquired	$ 300,668

Real Estate Amortization of Finite Lived Intangible Assets (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
2023	$ 3,911
2024	2,200
In-Place Lease Intangibles \| 153 & 211 Second Avenue and Shady Grove Innovation District [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022	9,691
2023	151
2024	56
Above Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022	428
2023	208
2024	147
Above Market Lease Intangibles [Member] \| 153 & 211 Second Avenue and Shady Grove Innovation District [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022	74
2023	25
2024	12
Below Market Lease Intangible [Member] \| 153 & 211 Second Avenue and Shady Grove Innovation District [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022	1,713
2023	39
2024	$ 26

Leases Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Leases Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Lessor, Lease, Description [Line Items]
Write-off for accrued rent and accounts receivables	$ 1,300	$ 90,300

Lessee leases (narrative)(Details) $ in Thousands			12 Months Ended
Lessee leases (narrative)(Details) $ in Thousands	Jul. 01, 2021 USD ($)	May 19, 2021 USD ($) ft²	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Number of Properties Subject to Ground Leases			4	4	4
Operating Lease, Payments			$ 23,599	$ (1,533)	$ (1,616)
Right of use assets - operating leases			22,300	22,500
Present value of lease payments			30,400	29,000
Operating lease costs			$ 13,151	$ 13,948	$ 14,573
Property Subject to Operating Lease
Lessee, Lease, Description [Line Items]
Number of Properties Subject to Ground Leases			4	4	4
Sumner Square
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Description		for an additional 15 years. Prior to the amendment, the ground lease was scheduled to expire on August 10, 2066. The ground lease will now expire on August 9, 2081.
Operating Lease, Payments	$ 23,000
Lessee Operating Lease Liability Payments Due, Next Five Years		$ 4,000
Lessee, Operating Lease, Discount Rate		3.95%
Operating Lease, Liability		$ 26,700
Right of use assets - operating leases		27,100
Present value of lease payments		$ 26,670	$ 3,400
Net Rentable Area (in sf) \| ft²		210,000
Operating lease costs			$ 700	$ 1,400	$ 1,500

Lessee, Lease Cost and Other Information (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2021

USD ($)

Dec. 31, 2020

USD ($)

Dec. 31, 2019

USD ($)

Amortization of right-of-use asset

Operating lease costs

$ 13,151

$ 13,948

$ 14,573

^[1]

547

Interest on lease liabilities

^[2]

$ 2,471

$ 583

$ 47

Operating leases, Weighted-average remaining lease term

50 years

51 years

Finance leases, Weighted-average remaining lease term

69 years

70 years

Operating leases, Weighted-average discount rate

5.70%

Finance leases, Weighted-average discount rate

6.20%

Finance leases under development

[1]

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

[2]

Two, three and three of the finance leases relate to assets under development for all or a portion of the years ended December 31, 2021, December 31, 2020 and December 31, 2019, respectively, and as such, a portion of the interest amount was capitalized.

Lease Liability Maturity Schedule (Details) - USD ($)
$ in Thousands

Dec. 31, 2021

Dec. 31, 2020

Lessee, Operating Lease, Liability, Payment, Due [Abstract]

$ 19,623

$ 25,092

25,333

18,020

10,085

10,262

10,307

9,277

2026

10,100

9,476

538,801

548,478

614,249

620,605

(409,688)

(418,892)

Finance Lease, Liability, Payment, Due [Abstract]

30,400

29,000

8,762

5,896

10,826

10,206

48,605

^[1]

9,701

9,971

48,518

^[1]

2026

10,166

9,971

1,363,011

1,373,177

1,451,341

1,457,469

(1,206,920)

(1,220,977)

385,500

388,700

Lessee purchase option reasonably certain of exercising

$ 38,700

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

Lease Liability Maturity Detail Prior Year (Details) - USD ($)
$ in Thousands

Dec. 31, 2021

Dec. 31, 2020

Lessee, Operating Lease, Liability, Payment, Due [Abstract]

2021

$ 19,623

$ 25,092

25,333

18,020

10,085

10,262

10,307

9,277

10,100

9,476

538,801

548,478

614,249

620,605

(409,688)

(418,892)

Finance Lease, Liability, Payment, Due [Abstract]

30,400

29,000

2021

8,762

5,896

10,826

10,206

48,605

^[1]

9,701

9,971

48,518

^[1]

10,166

9,971

1,363,011

1,373,177

1,451,341

1,457,469

(1,206,920)

(1,220,977)

Schedule of Equity Method Investments [Line Items]

$ 385,500

$ 388,700

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

Lease Liability Maturity Schedule - Sumner Square (Details) - USD ($) $ in Thousands	Dec. 31, 2021	May 19, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
2022	$ 19,623		$ 25,092
2023	25,333		18,020
2024	10,085		10,262
2025	10,307		9,277
2026	10,100		9,476
Thereafter	538,801		548,478
Total lease payments	614,249		620,605
Less: Interest Portion	(409,688)		(418,892)
Present value of lease payments	30,400		$ 29,000
Sumner Square
Lessee, Lease, Description [Line Items]
2022		$ 23,599
2023		761
2024		784
2025		808
2026		832
Thereafter		422
Total lease payments		27,206
Less: Interest Portion		(536)
Present value of lease payments	$ 3,400	$ 26,670

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Fixed contractual payments	$ 2,319,362	$ 2,211,915	$ 2,261,260
Variable lease payments	433,652	434,346	496,754
Lease	$ 2,753,014	$ 2,646,261	$ 2,758,014

Future Minimum Rent (Details) $ in Thousands	12 Months Ended
Future Minimum Rent (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
2022	$ 2,252,034
2023	2,251,287
2024	2,138,772
2025	2,012,975
2026	1,877,563
Thereafter	$ 12,215,114
Schedule of Future Minimum Lease Payments
Concentration Risk, Percentage	10.00%	10.00%	10.00%
Number Of Tenants Above Concentration Amount.	0	0	0

Deferred Charges (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Leasing costs, including lease related intangibles	$ 1,011,229	$ 1,023,058
Financing costs	19,231	12,728
Deferred Costs Gross	1,030,460	1,035,786
Less: Accumulated amortization	(411,662)	(395,701)
Deferred Costs, total	$ 618,798	$ 640,085

Deferred Charges Schedule of Acquired In-Place Lease Intangibles (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2022	$ 13,827
2023	3,911
2024	2,200
2025	2,112
2026	$ 1,624

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

12 Months Ended

Dec. 31, 2021

USD ($)

ft²

payments

Dec. 15, 2021

Sep. 01, 2021

Aug. 31, 2021

Mar. 30, 2021

Feb. 25, 2021

Dec. 31, 2020

USD ($)

^[1]

$ (652,135)

$ (650,433)

Investments In Affiliates Subsidiaries Associates And Joint Ventures net

^[2]

1,445,926

1,273,919

^[3]

1,445,926

1,273,919

Unconsolidated Joint Ventures [Member]

Schedule of Equity Method Investments [Line Items]

Square 407 Limited Partnership [Member]

$ (37,100)

(36,600)

Schedule of Equity Method Investments [Line Items]

Market Square North

50.00%

BP/CRF Metropolitan Square LLC [Member]

^[3]

$ (1,205)

(3,766)

Schedule of Equity Method Investments [Line Items]

Metropolitan Square

20.00%

901 New York Avenue LLC [Member]

^[3]

$ (15,356)

(13,584)

Schedule of Equity Method Investments [Line Items]

901 New York Avenue

^[4]

25.00%

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

^[3]

$ (12,597)

$ (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

^[5]

33.33%

Annapolis Junction NFM, LLC [Member]

^[3]

$ 33,732

$ 35,297

Schedule of Equity Method Investments [Line Items]

Annapolis Junction

50.00%

^[6]

Schedule of Equity Method Investments [Line Items]

^[3]

$ 13,463

540 Madison Venture

540 Madison Avenue

^[7]

60.00%

500 North Capitol Venture LLC [Member]

^[3]

122

Schedule of Equity Method Investments [Line Items]

500 North Capitol Street, NW

30.00%

501 K Street LLC [Member]

^[3]

$ (7,913)

(6,945)

Schedule of Equity Method Investments [Line Items]

1001 6th Street

^[8]

50.00%

Potential additonal payments to joint venture partner | payments

^[3]

$ 42,576

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]

^[3]

$ 48,980

48,818

Schedule of Equity Method Investments [Line Items]

Hub50House

50.00%

Hotel Tower Developer LLC [Member]

^[3]

$ 47,774

50,943

Schedule of Equity Method Investments [Line Items]

The Hub on Causeway - Hotel Air Rights

50.00%

Office Tower Developer LLC [Member]

^[3]

$ 11,505

10,754

Schedule of Equity Method Investments [Line Items]

100 Causeway Street

50.00%

1265 Main Office JV LLC [Member]

^[3]

$ 57,687

56,312

Schedule of Equity Method Investments [Line Items]

1265 Main Street

50.00%

BNY Tower Holdings LLC [Member]

^[3]

$ 3,541

3,787

Schedule of Equity Method Investments [Line Items]

Dock 72

50.00%

BNYA Amenity Operator LLC [Member]

^[3]

$ 27,343

29,536

Schedule of Equity Method Investments [Line Items]

Dock 72

50.00%

CA-Colorado Center Limited Partnership [Member]

^[3]

$ 1,069

1,846

Schedule of Equity Method Investments [Line Items]

Colorado Center

50.00%

7750 Wisconsin Avenue LLC [Member]

^[3]

$ 231,479

227,671

Schedule of Equity Method Investments [Line Items]

7750 Wisconsin Avenue

50.00%

BP-M 3HB Venture LLC [Member]

^[3]

$ 61,626

58,112

Schedule of Equity Method Investments [Line Items]

3 Hudson Boulevard

25.00%

Schedule of Equity Method Investments [Line Items]

^[3]

$ 116,306

113,774

SMBP Venture LP [Member]

Santa Monica Business Park

55.00%

Platform 16 Holdings LP [Member]

^[3]

$ 156,639

145,761

Schedule of Equity Method Investments [Line Items]

Platform 16

^[9]

55.00%

Gateway Portfolio Holdings LLC [Member]

^[3]

$ 109,086

$ 108,393

Schedule of Equity Method Investments [Line Items]

Gateway Commons

50.00%

^[10]

54.00%

55.00%

Rosecrans-Sepulveda Partners 4, LLC

^[3]

$ 327,148

$ 336,206

Schedule of Equity Method Investments [Line Items]

Beach Cities Media Campus

50.00%

Entity Owning Land And Infrastructure Of Project [Member]

^[3]

$ 27,106

$ 27,184

Schedule of Equity Method Investments [Line Items]

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

33.33%

Schedule of Equity Method Investments [Line Items]

Schedule of Equity Method Investments [Line Items]

50.00%

55.00%

Safeco Plaza REIT LLC

Safeco Plaza

33.67%

^[11]

33.67%

Safeco Plaza REIT LLC | Company's Share [Member]

^[3]

$ 72,545

Schedule of Equity Method Investments [Line Items]

Schedule of Equity Method Investments [Line Items]

33.00%

360 PAS Holdco LLC

360 Park Avenue South

42.21%

^[12]

42.21%

360 PAS Holdco LLC | Company's Share [Member]

^[3]

$ 106,855

Schedule of Equity Method Investments [Line Items]

Safeco Partner Entity Two | Company's Share [Member]

35.79%

Schedule of Equity Method Investments [Line Items]

Safeco Partner Entity One [Member] | Company's Share [Member]

1.00%

Schedule of Equity Method Investments [Line Items]

360 Park Avenue South Partners Entity | Company's Share [Member]

1.00%

Schedule of Equity Method Investments [Line Items]

360 PAS Holdco LLC (indirect ownership) | Company's Share [Member]

1.00%

Schedule of Equity Method Investments [Line Items]

360 Park Avenue South Partners Entity Two | Company's Share [Member]

5.837%

Schedule of Equity Method Investments [Line Items]

Real estate and development in process, net

1.00%

[1]	At December 31, 2021 and December 31, 2020, this amount included lease liabilities - finance leases totaling approximately $385.5 million and $388.7 million, respectively, and lease liabilities - operating leases totaling approximately $30.4 million and $29.0 million, respectively.
[2]	Investments with deficit balances aggregating approximately $37.1 million and $36.6 million at December 31, 2021 and 2020, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.
[3]	Investments with deficit balances aggregating approximately $37.1 million and $36.6 million at December 31, 2021 and December 31, 2020, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.
[4]	The Company’s economic ownership has increased based on the achievement of certain return thresholds. At December 31, 2021 and December 31, 2020, the Company’s economic ownership was approximately 50%.
[5]	The Company’s wholly-owned subsidiary that owns Wisconsin Place Office also owns a 33.33% interest in the joint venture entity that owns the land, parking garage and infrastructure of the project.
[6]	On March 30, 2021, the Company sold its interest in the joint venture to the partner. See below for additional details.
[7]	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 December 31, 2021 and the joint venture has been dissolved.
[8]	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.
[9]	This entity is a VIE (See Note 2).
[10]	As a result of the partner’s deferred contribution, the Company owned an approximately 50% and 55% interest in the joint venture at December 31, 2021 and December 31, 2020, respectively.
[11]	The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities (each, a “Safeco Partner Entity”) through which each partner owns its interest in the joint venture.
[12]	The Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the two entities (each, a “360 Park Avenue South Partner Entity”) through which each partner owns its interest in the joint venture.

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

Dec. 31, 2021

Dec. 31, 2020

ASSETS

^[1]

$ 5,579,218

$ 4,708,571

Other assets

586,470

531,071

Total assets

6,165,688

5,239,642

Mortgage and notes payable, net

3,214,961

2,637,911

Members’/Partners’ equity

^[2]

652,135

650,433

2,298,592

1,951,298

Total liabilities and equity / capital

6,165,688

5,239,642

Company's share of equity

1,104,175

936,087

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

^[3]

341,751

337,832

^[4]

1,445,926

1,273,919

248,900

Lease liabilities - finance leases

22,300

22,500

385,500

388,700

Lease liabilities - operating leases

30,400

29,000

Unconsolidated Joint Ventures [Member]

37,100

36,600

Colorado Center

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

304,776

307,328

^[5]

231,479

227,671

Gateway Commons Complex [Member]

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

51,009

51,875

^[5]

327,148

336,206

Dock 72

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

(50,051)

(52,243)

^[5]

$ 27,343

$ 29,536

[1]

At December 31, 2021 and December 31, 2020, this amount included right of use assets - finance leases totaling approximately $248.9 million. At December 31, 2021 and December 31, 2020, this amount included right of use assets - operating leases totaling approximately $22.3 million and $22.5 million, respectively.

[2]

At December 31, 2021 and December 31, 2020, this amount included lease liabilities - finance leases totaling approximately $385.5 million and $388.7 million, respectively, and lease liabilities - operating leases totaling approximately $30.4 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 majority of the Company’s basis differences are as follows:


	December 31, 2021		December 31, 2020
Property	(in thousands)
Colorado Center	$	304,776	$	307,328
Gateway Commons	51,009		51,875
Dock 72	(50,051)		(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 $37.1 million and $36.6 million at December 31, 2021 and 2020, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

[5]

Investments with deficit balances aggregating approximately $37.1 million and $36.6 million at December 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

12 Months Ended

Mar. 30, 2021

Dec. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

Schedule of Equity Method Investments [Line Items]

^[1]

$ 383,649

$ 319,560

$ 322,817

Expenses

Operating

158,498

144,347

122,992

Depreciation and amortization

470

1,027

1,000

147,121

141,853

102,296

Total expenses

306,089

287,227

226,288

(108,884)

(98,051)

(84,409)

11,737

^[2]

32,706

^[2]

Company's share of net income

(31,324)

(53,981)

44,826

(10,254)

(16,256)

24,423

10,257

^[3]

Income (Loss) from Equity Method Investments

(60,524)

^[4]

Basis differential

^[5]

(2,573)

(8,330)

^[2],[4]

22,169

^[2]

(2,570)

(85,110)

46,592

Straight-line rent adjustments

17,200

(10,100)

32,400

Above and below market rent adjustments, net

4,200

6,500

20,900

Write-off for accrued rent and accounts receivables

$ 1,300

$ 90,300

540 Madison Avenue [Member]

47,200

Annapolis Junction NFM, LLC [Member]

^[6]

60.00%

$ 10,300

50.00%

^[7]

Colorado Center [Member]

Straight-line rent adjustments

800

$ 1,800

2,100

Above and below market rent adjustments, net

$ 400

900

$ 1,700

Dock 72 [Member]

Schedule of Equity Method Investments [Line Items]

$ (60,500)

[1]	Includes straight-line rent adjustments of approximately $17.2 million, $(10.1) million and $32.4 million for the years ended December 31, 2021, 2020 and 2019, respectively
[2]	For the year ended December 31, 2020, represents the gain on sale of Annapolis Junction Building Eight and two land parcels. For the year ended December 31, 2019, represents the gain on sale of 540 Madison Avenue recognized by the joint venture. During 2008, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture resulting in a basis differential between the carrying value of the Company’s investment in the joint venture and the joint venture’s basis in the assets and liabilities of the property. As a result of the historical basis difference, the Company recognized a gain on sale of real estate totaling approximately $47.2 million for the year ended December 31, 2019, which consists of its share of the gain on sale reported by the joint venture as well as an adjustment for the basis differential. The gain on sale of real estate is included in Income (loss) from Unconsolidated Joint Ventures in the Company’s Consolidated Statements of Operations.
[3]	During the year ended December 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.
[4]	During the year ended December 31, 2020, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $60.5 million.
[5]	Includes straight-line rent adjustments of approximately $0.8 million, $1.8 million and $2.1 million for the years ended December 31, 2021, 2020 and 2019, respectively. Also includes net above-/below-market rent adjustments of approximately $0.4 million, $0.9 million and $1.7 million for the years ended December 31, 2021, 2020 and 2019, respectively.
[6]	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 December 31, 2021 and the joint venture has been dissolved.
[7]	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

12 Months Ended

Dec. 31, 2021

USD ($)

Dec. 14, 2021

USD ($)

ft²

loanExtension

Rate

Sep. 01, 2021

USD ($)

ft²

Aug. 31, 2021

USD ($)

ft²

loanExtension

years

Mar. 30, 2021

USD ($)

ft²

Dec. 31, 2021

USD ($)

Dec. 31, 2020

USD ($)

Dec. 31, 2019

USD ($)

Dec. 15, 2021

Oct. 29, 2021

ft²

Jun. 11, 2021

ft²

Feb. 25, 2021

ft²

Mortgage notes payable, net

$ 3,214,961

$ 2,637,911

Debt Instrument, Basis Spread on Variable Rate

0.775%

Proceeds from Sale of Equity Method Investments

17,789

$ 0

Income (Loss) from Equity Method Investments

98,152

172,436

87,392

(2,570)

(85,110)

46,592

Capital distributions from unconsolidated joint ventures

122

55,298

136,807

Proceeds from sales of real estate

179,887

519,303

90,824

60,524

^[1]

Repayments of Secured Debt

10,257

^[2]

$ 832,296

$ 17,168

$ 46,173

7750 Wisconsin Avenue [Member]

Schedule of Equity Method Investments [Line Items]

50.00%

Schedule of Equity Method Investments [Line Items]

733,000

360 Park South Avenue

42.21%

450,000

Number of floors

360 Park South Avenue | Adjustable Rate Loans

Debt - Total loan amount

$ 220,000

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Basis Spread on Variable Rate | Rate

2.40%

Number of extensions | loanExtension

Extension Option (in years) | yr

Debt - Total loan amount

$ 220,000

Proceeds from Issuance of Debt

$ 202,000

Gateway Commons Complex [Member]

Schedule of Equity Method Investments [Line Items]

Gateway Commons Complex [Member] | Scenario, Plan

50.00%

^[3]

50.00%

^[3]

55.00%

54.00%

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]

Schedule of Equity Method Investments [Line Items]

50.00%

55.00%

Platform 16

Annapolis Junction NFM, LLC [Member]

^[4]

55.00%

Schedule of Equity Method Investments [Line Items]

Proceeds from Sale of Equity Method Investments

50.00%

^[5]

Contractual Sales Price

$ 65,900

17,800

Capital distributions from unconsolidated joint ventures

5,800

Repayments of Secured Debt

10,300

$ 10,300

$ 15,100

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

Schedule of Equity Method Investments [Line Items]

Schedule of Equity Method Investments [Line Items]

247,000

Dock 72 [Member]

100 Causeway Street [Member]

$ 60,500

Schedule of Equity Method Investments [Line Items]

100 Causeway Street [Member] | Unconsolidated Properties

50.00%

Schedule of Equity Method Investments [Line Items]

50.00%

Schedule of Equity Method Investments [Line Items]

634,000

Safeco Plaza REIT LLC

Mortgage notes payable, net

33.67%

^[6]

33.67%

^[6]

$ 250,000

765,000

Debt Instrument, Description of Variable Rate Basis

$ 72,600

variable rate equal to the greater of (x) 2.35% or (y) LIBOR plus 2.20% per annum

Aggregate purchase price

$ 460,100

Number of floors

Acquisition Costs, Period Cost

$ 4,900

Podium Developer LLC [Member]

Schedule of Equity Method Investments [Line Items]

Mortgage notes payable, net

50.00%

$ 174,300

Debt Instrument, Basis Spread on Variable Rate

2.25%

Number of extensions | loanExtension

382,000

Extension Option (in years) | years

360 PAS Holdco LLC

Schedule of Equity Method Investments [Line Items]

42.21%

^[7]

42.21%

^[7]

42.21%

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

Schedule of Equity Method Investments [Line Items]

Company's Share [Member] | Safeco Plaza REIT LLC

231,000

Schedule of Equity Method Investments [Line Items]

Company's Share [Member] | Safeco Partner Entity One [Member]

33.00%

Schedule of Equity Method Investments [Line Items]

Company's Share [Member] | Safeco Partner Entity Two

1.00%

Schedule of Equity Method Investments [Line Items]

Company's Share [Member] | 360 Park Avenue South Partners Entity Two

1.00%

Schedule of Equity Method Investments [Line Items]

Company's Share [Member] | 360 Park Avenue South Partners Entity

1.00%

Schedule of Equity Method Investments [Line Items]

Company's Share [Member] | 360 PAS Holdco LLC (indirect ownership)

1.00%

Schedule of Equity Method Investments [Line Items]

Company's Share [Member] | 360 PAS Holdco LLC

5.837%

Schedule of Equity Method Investments [Line Items]

Institutional investor number one | Safeco Plaza REIT LLC

35.79%

Schedule of Equity Method Investments [Line Items]

33.165%

Institutional investor number two | Safeco Plaza REIT LLC

$ 71,900

Schedule of Equity Method Investments [Line Items]

33.165%

Institutional investors | 360 PAS Holdco LLC

$ 71,900

Schedule of Equity Method Investments [Line Items]

58.00%

[1]	During the year ended December 31, 2020, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $60.5 million.
[2]	During the year ended December 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]	As a result of the partner’s deferred contribution, the Company owned an approximately 50% and 55% interest in the joint venture at December 31, 2021 and December 31, 2020, respectively.
[4]	This entity is a VIE (See Note 2).
[5]	On March 30, 2021, the Company sold its interest in the joint venture to the partner. See below for additional details.
[6]	The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities (each, a “Safeco Partner Entity”) through which each partner owns its interest in the joint venture.
[7]	The Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the two entities (each, a “360 Park Avenue South Partner Entity”) through which each partner owns its interest in the joint venture.

Investments in Unconsolidated Joint Ventures - Purchase Price Allocation (Details) - Safeco Plaza - Safeco Plaza REIT LLC $ in Thousands	Sep. 01, 2021 USD ($)
Schedule of Equity Method Investments [Line Items]
Land	$ 81,343
Building and improvements	351,948
Tenant improvements	30,404
Net assets acquired	460,112
In-Place Lease Intangibles
Schedule of Equity Method Investments [Line Items]
Lease Intangibles	28,658
Above Market Lease Intangibles [Member]
Schedule of Equity Method Investments [Line Items]
Lease Intangibles	301
Below Market Lease Intangible [Member]
Schedule of Equity Method Investments [Line Items]
Lease Intangibles	$ (32,542)

Investments in Unconsolidated Joint Ventures - Amortization of Finite Lived Intangible Assets(Details) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 01, 2021
Acquired Finite-Lived Intangible Assets [Line Items]
2023	$ 3,911
2024	2,200
2025	2,112
2026	1,624
Above Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022	428
2023	208
2024	147
2025	135
2026	$ 135
Safeco Plaza \| Safeco Plaza REIT LLC \| In-Place Lease Intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
2022		$ 4,278
2023		3,453
2024		3,036
2025		2,851
2026		2,749
Safeco Plaza \| Safeco Plaza REIT LLC \| Above Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022		49
2023		49
2024		49
2025		49
2026		42
Safeco Plaza \| Safeco Plaza REIT LLC \| Below Market Lease Intangible [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2022		4,663
2023		4,596
2024		4,383
2025		4,337
2026		$ 4,329

Mortgage Notes Payable, Net (Details) $ in Thousands					12 Months Ended
Mortgage Notes Payable, Net (Details) $ in Thousands	Dec. 31, 2021 USD ($) Rate	Dec. 14, 2021 USD ($) yr loanExtension Rate shares	Dec. 10, 2021 USD ($) Rate	Mar. 26, 2021 USD ($) Rate	Dec. 31, 2021 USD ($) Rate	Dec. 31, 2020 USD ($) Rate	Dec. 31, 2019 USD ($)	Dec. 15, 2021	Dec. 09, 2021 USD ($) Rate
Debt Instrument [Line Items]
Mortgage notes payable, net	$ 3,214,961				$ 3,214,961	$ 2,637,911
Debt Instrument, Collateral					each collateralized by one or more buildings and related land included in real estate assets	each collateralized by one or more buildings and related land included in real estate assets
Number Of Variable Mortgage Loans	0				0	0
Repayments of Secured Debt					$ 832,296	$ 17,168	$ 46,173
Loss from early extinguishment of debt					45,182	0	29,540
Assumption of mortgage notes payable					200,311	0	$ 0
Debt Instrument, Basis Spread on Variable Rate	0.775%
601 Lexington Avenue
Debt Instrument [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent			55.00%
Loss from early extinguishment of debt			$ 100
360 Park South Avenue
Debt Instrument [Line Items]
Debt - Total loan amount		$ 220,000
Noncash or Part Noncash Acquisition, Value of Assets Acquired		300,700
Assumption of mortgage notes payable		$ 200,300
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued \| shares		866,503
number of investors								2
Ownership Percentage								42.21%
Fixed Rate Mortgage [Member]
Debt Instrument [Line Items]
Mortgage notes payable, net	$ 3,300,000				$ 3,300,000	$ 2,900,000
Debt, Weighted Average Interest Rate \| Rate	3.24%				3.24%	3.72%
Fixed Rate Mortgage [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	2.79%				2.79%	3.43%
Fixed Rate Mortgage [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate	3.43%				3.43%	6.94%
Fixed Rate Mortgage [Member] \| University Place
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate				6.94%
Repayments of Secured Debt				$ 900
Fixed Rate Mortgage [Member] \| 601 Lexington Avenue
Debt Instrument [Line Items]
Mortgage notes payable, net			$ 1,000,000						$ 616,100
Debt Instrument, Interest Rate, Stated Percentage \| Rate			2.79%						4.75%
Fixed Rate Mortgage [Member] \| 360 Park South Avenue
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage \| Rate		6.044%
Repayments of Secured Debt		$ 200,300
Adjustable Rate Loans \| 360 Park South Avenue
Debt Instrument [Line Items]
Debt - Total loan amount		220,000
Proceeds from Issuance of Debt		$ 202,000
Debt Instrument, Basis Spread on Variable Rate \| Rate		2.40%
Number of extensions \| loanExtension		2
Extension Option (in years) \| yr		1

Schedule of Aggregate Principal Payments on Mortgage Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
2022	$ 0
2023	0
2024	0
2025	0
2026	0
Thereafter	3,300,000
Total	3,300,000
Deferred financing costs, net	(32,100)
Mortgage notes payable, net	3,214,961	$ 2,637,911
Debt Instrument [Line Items]
2022	0
2023	0
2024	0
2025	0
2026	0
Thereafter	3,300,000
Total	3,300,000
Debt Issuance Costs, Net	(32,100)
Secured Debt	$ 3,214,961	$ 2,637,911

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

Dec. 31, 2021

Sep. 29, 2021

Mar. 16, 2021

Dec. 31, 2020

Debt Issuance Costs, Net

$ (32,100)

9,483,695

$ 9,639,287

Debt Instrument, Unamortized Discount

9,550,000

16,548

Debt Issuance Costs, Net

49,757

Senior Notes | 3.279% unsecured senior notes

$ 9,483,695

3.125%

Debt Instrument, Interest Rate, Effective Percentage

$ 500,000

^[1]

3.279%

Senior Notes | 3.916% unsecured senior notes

^[2]

Sep. 01, 2023

3.80%

Debt Instrument, Interest Rate, Effective Percentage

$ 700,000

^[1]

3.916%

Senior Notes | 3.350% unsecured senior notes

^[2]

Feb. 01, 2024

3.20%

Debt Instrument, Interest Rate, Effective Percentage

$ 850,000

^[1]

3.35%

Senior Notes | 3.766% unsecured senior notes

^[2]

Jan. 15, 2025

3.65%

Debt Instrument, Interest Rate, Effective Percentage

$ 1,000,000

^[1]

3.766%

Senior Notes | 3.495% unsecured senior notes

^[2]

Feb. 01, 2026

2.75%

Debt Instrument, Interest Rate, Effective Percentage

$ 1,000,000

^[1]

3.495%

Senior Notes | 4.628% unsecured senior notes

^[2]

Oct. 01, 2026

4.50%

Debt Instrument, Interest Rate, Effective Percentage

$ 1,000,000

^[1]

4.628%

Senior Notes | 3.505% unsecured senior notes

^[2]

Dec. 01, 2028

3.40%

Debt Instrument, Interest Rate, Effective Percentage

$ 850,000

^[1]

3.505%

Senior Notes | 2.984% unsecured senior notes

^[2]

Jun. 21, 2029

2.90%

Debt Instrument, Interest Rate, Effective Percentage

$ 700,000

^[1]

2.984%

Senior Notes | 3.343 % unsecured senior notes

^[2]

Mar. 15, 2030

3.25%

Debt Instrument, Interest Rate, Effective Percentage

$ 1,250,000

^[1]

3.343%

Senior Notes | 2.671% unsecured senior notes

^[2]

Jan. 30, 2031

2.55%

Debt Instrument, Interest Rate, Effective Percentage

$ 850,000

2.671%

^[1]

2.671%

Senior Notes | 2.524% unsecured senior notes

^[2]

Apr. 01, 2032

2.45%

Debt Instrument, Interest Rate, Effective Percentage

$ 850,000

2.524%

^[1]

2.524%

^[2]

Oct. 01, 2033

[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

12 Months Ended

Oct. 15, 2021

Sep. 29, 2021

Mar. 16, 2021

Feb. 14, 2021

Dec. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

Repayments of Unsecured Debt

$ 1,841,500

$ 0

$ 699,237

Proceeds from unsecured senior notes

45,182

29,540

1,695,996

1,248,125

1,548,106

Debt prepayment and extinguishment costs

(43,036)

$ (28,716)

9,483,695

$ 9,639,287

Debt Instrument, Covenant Description

$ 9,550,000

Debt Instrument, Covenant Compliance

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

2.671% unsecured senior notes | Senior Notes

$ 9,483,695

$ 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

$ 850,000

Repayments of Unsecured Debt

4.125%

$ 858,700

Debt Instrument, Increase, Accrued Interest

8,700

2.524% unsecured senior notes | Senior Notes

$ 400

$ 850,000

Debt Instrument, Interest Rate, Effective Percentage

2.45%

Senior Notes Pricing

99.959%

2.524%

^[1]

Proceeds from unsecured senior notes

$ 842,500

3.954% unsecured senior notes | Senior Notes

$ 1,000,000

Repayments of Unsecured Debt

3.85%

$ 1,050,000

Debt Instrument, Increase, Accrued Interest

7,900

Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed

$ 44,200

104.284%

Debt prepayment and extinguishment costs

$ 42,800

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

Unsecured Credit Facility (Details) - USD ($) $ in Thousands				12 Months Ended
	Dec. 31, 2021	Jun. 15, 2021	Mar. 16, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Line of Credit Facility [Line Items]
Repayments of Unsecured Debt				$ 1,841,500	$ 0	$ 699,237
Loss from early extinguishment of debt				$ 45,182	0	$ 29,540
Line of Credit Facility, Expiration Date		Jun. 15, 2026
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,500,000
Line of Credit, Additional Borrowing Capacity		$ 500,000
Line of Credit Facility, Interest Rate Description		At Boston Properties Limited Partnership’s option, loans under the 2021 Credit Facility will bear interest at a rate per annum equal to (1) (a) in the case of loans denominated in Dollars, LIBOR, (b) in the case of loans denominated in Euro, EURIBOR, (c) in the case of loans denominated in Canadian Dollars, CDOR, and (d) in the case of loans denominated in Sterling, SONIA, in each case, plus a margin ranging from 70.0 to 140.0 basis points based on Boston Properties Limited Partnership’s credit rating or (2) an alternate base rate equal to the greatest of (a) the Federal Funds rate plus 0.5%, (b) the Administrative Agent’s prime rate, (c) LIBOR for a one-month period plus 1.00%, and (d) 1.00%, in each case, plus a margin ranging from 0 to 40 basis points based on Boston Properties Limited Partnership’s credit rating.
Line of credit facility, maximum percent for loan advances		65.00%
Line of Credit Facility, Commitment Fee Percentage	0.15%
Debt Instrument, Basis Spread on Variable Rate	0.775%
Debt Instrument, Alternate Basis Spread on Variable Rate	0.00%			0.00%
Long-term Line of Credit	$ 145,000			$ 145,000	0
Unsecured term loan, net	0			$ 0	499,390
Line of Credit Facility, Covenant Terms		Among other covenants, the 2021 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.
Line of Credit Facility, Covenant Compliance				At December 31, 2021, Boston Properties Limited Partnership was in compliance with each of these financial and other covenant requirements.
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage		0.30%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		1.40%
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage		0.10%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.70%
Delayed Draw Facility [Member]
Line of Credit Facility [Line Items]
Repayments of Unsecured Debt			$ 500,000
Loss from early extinguishment of debt			$ 500
Line of Credit Facility, Maximum Borrowing Capacity		$ 500,000
Unsecured term loan, net					$ 500,000
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Long-term Line of Credit	$ 145,000			$ 145,000

Commitments And Contingencies (Details)	12 Months Ended
Commitments And Contingencies (Details)	Dec. 31, 2021 USD ($) ft²	Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations	$ 26,400,000
Notes receivable, net	$ 10,000,000	$ 18,729,000
Note receivable fixed interest rate	8.00%
Property insurance program per occurrence limits	$ 1,000,000,000
Per occurrence limit for NBCR Coverage	1,000,000,000
Value of program trigger	$ 200,000,000
Coinsurance of program trigger	20.00%
Program trigger deductible	20.00%
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
Deductible in insurance as a percentage of the value of the affected property, San Francisco and Los Angeles	3.00%
Per Occurrence Limit of Earthquake Insurance Seattle	$ 60,000,000
Annual Aggregate Limit of Earthquake Insurance Seattle	$ 60,000,000
Earthquake Deductible Insurance Percentage of Value of the Affected Property Seattle	2.00%
Operating partnership guarantee to cover liabilities of IXP	$ 20,000,000
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation	19,000,000
Property insurance program per occurrence limits	1,625,000,000
7750 Wisconsin Avenue [Member]
Commitments And Contingencies [Line Items]
Liabilities for Contingent Guarantees	$ 0
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	$ 1,350,000,000
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP - Property and Terrorism	750,000,000
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP - Terrorism	600,000,000
Sum of Coverage Covered by IXP and Excess Coverage for Property and Terrorism	$ 1,750,000,000
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	Dec. 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	$ 1,556,553	$ 1,726,933
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	16,561,186
LTIP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	1,485,376
2012 OPP and 2013-2018 MYLTIP
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	418,974
MYLTIP 2019 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	219,916
MYLTIP 2020 [Member]
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]
Noncontrolling Interest, Outstanding	352,021

(Common Units) (Narrative) (Details) $ / shares in Units, $ in Thousands						12 Months Ended
	Dec. 14, 2021 USD ($) shares	Feb. 05, 2021 USD ($) shares	Feb. 02, 2021 USD ($)	Feb. 06, 2020 USD ($) shares	Feb. 09, 2019 USD ($) shares	Dec. 31, 2021 USD ($) yr $ / shares shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount \| $						$ 2,078,603	$ 1,643,024
Vesting Period						4 years
Issuance of operating partnership units for 360 Park Avenue South \| $						$ 99,689	$ 0	$ 0
360 Park South Avenue
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued	866,503
Issuance of operating partnership units for 360 Park Avenue South \| $	$ 99,700
MYLTIP
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Vesting Period						3 years
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 2016 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target					69.50%
Value of MYLTIP Awards \| $					$ 13,600
Forfeitures, in units					364,980
MYLTIP 2017 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target				83.80%
Value of MYLTIP Awards \| $				$ 17,600
Forfeitures, in units				270,942
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 2019 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding						219,916
MYLTIP 2020 [Member]
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
Noncontrolling Interest, Outstanding						352,021
Vesting Period			3 years
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares)						523,969	856,811
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 \| $						$ 2,100,000
Closing price of common stock (in dollars per share) \| $ / shares						$ 115.18
Noncontrolling Interest [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Issuance of operating partnership units for 360 Park Avenue South \| $						$ 99,689
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)						148,442	88,168

Noncontrolling Interests Common Units Distributions (Details) - $ / shares	Oct. 29, 2021	Jul. 30, 2021	Apr. 30, 2021	Jan. 28, 2021	Oct. 30, 2020	Jul. 31, 2020	Apr. 30, 2020	Jan. 30, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 30, 2019	Dec. 20, 2021
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit													$ 0.98
Dividends, Per Unit, Cash Paid	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.95	$ 0.95	$ 0.95	$ 0.95
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	0.98	0.98	0.98	0.98	0.98	0.95	0.95	0.95	0.95
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	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.095	$ 0.095	$ 0.095	$ 0.095

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Noncontrolling Interest [Line Items]
Noncontrolling Interest in Limited Partnerships	$ 1,556,553	$ 1,726,933

Stockholders' Equity / Partners' Capital Narrative (Details) $ / shares in Units, $ in Thousands					12 Months Ended
	Apr. 01, 2021 shares	Mar. 31, 2021 USD ($)	Mar. 02, 2021 $ / shares shares	May 22, 2020 USD ($) yr	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($)	Mar. 27, 2018 $ / shares	Jun. 02, 2017 USD ($)
Class of Stock [Line Items]
Common Stock, Shares, Outstanding					156,544,849	155,718,825
General Partners' Capital Account, Units Outstanding (in units)					1,745,914	1,730,921
Limited Partners' Capital Account, Units Outstanding (in units)					154,798,935	153,987,904
Options exercised					247,920	43,792
Shares of Common Stock issued in connection with redemption of an equal number of OP Units (in shares)					523,969	856,811
Preferred Stock Redemption Premium \| $					$ 6,412	$ 0	$ 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%			5.25%
Series B, Liquidation Preference Per Share (dollars per share) \| $ / shares						$ 2,500		$ 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)
Redeemable Preferred Stock Dividends \| $		1,300
Preferred Stock Redemption Premium \| $		$ 6,400
Preferred Stock, Redemption Date	Apr. 01, 2021
OP Units for redemption (in shares)	80,000
Depositary shares of Series B Cumulative Redeemable Preferred [Member]
Class of Stock [Line Items]
Series B, Shares Outstanding (in shares)						8,000,000
Series B, Liquidation Preference Per Share (dollars per share) \| $ / shares						$ 25.00		$ 25.00
OP Units for redemption (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

Segment Information Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Write-off for accrued rent and accounts receivables	$ 1,300	$ 90,300
Parking and Other [Member]
Segment Reporting Information [Line Items]
Increase (decrease) in parking and other revenue primarily related to COVID-19	11,100
Increase (decrease) in parking and other revenue primarily related to COVID-19	$ (32,900)

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

12 Months Ended

Dec. 31, 2021

Dec. 31, 2020

Dec. 31, 2019

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

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

$ 561,993,000

$ 979,979,000

$ 580,102,000

Preferred Stock Redemption Charge

(6,412,000)

Preferred dividends / distributions

(2,560,000)

(10,500,000)

Noncontrolling interest-common units of the Operating Partnership

(55,931,000)

(97,704,000)

(59,345,000)

Noncontrolling interest in property partnerships

(70,806,000)

(48,260,000)

(71,120,000)

(108,884,000)

(98,051,000)

(84,409,000)

Company's share of net operating income from joint ventures

45,182,000

29,540,000

(1,814,288,000)

(1,694,075,000)

(1,826,123,000)

Depreciation and amortization expense

(147,121,000)

(141,853,000)

(102,296,000)

General and administrative expense

(470,000)

(1,027,000)

(1,000,000)

(151,573,000)

(133,112,000)

(140,777,000)

Gains (losses) from investments in securities

(5,626,000)

(5,261,000)

(6,417,000)

Interest and other income (loss)

(5,704,000)

(5,953,000)

(18,939,000)

Income (loss) from unconsolidated joint ventures

(11,737,000)

^[1]

(32,706,000)

^[1]

2,570,000

85,110,000

(46,592,000)

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

561,993,000

979,979,000

580,102,000

Preferred Stock Redemption Charge

6,412,000

Preferred dividends / distributions

2,560,000

10,500,000

Noncontrolling interest-common units of the Operating Partnership

55,931,000

97,704,000

59,345,000

Noncontrolling interest in property partnerships

70,806,000

48,260,000

71,120,000

423,346,000

431,717,000

412,717,000

Company's share of net operating income from joint ventures

45,182,000

29,540,000

Impairment loss

22,272,000

107,756,000

94,943,000

97,716,000

Depreciation and amortization expense

709,035,000

676,666,000

669,956,000

General and administrative expense

5,036,000

1,531,000

1,984,000

Operating expense

12,487,000

11,626,000

10,386,000

151,573,000

133,112,000

140,777,000

Gains (losses) from investments in securities

5,626,000

5,261,000

6,417,000

Interest and other income (loss)

5,704,000

5,953,000

18,939,000

Income (loss) from unconsolidated joint ventures

125,198,000

631,945,000

858,000

2,570,000

85,110,000

(46,592,000)

Company's share of Net Operating Income

12,487,000

11,626,000

10,386,000

1,735,740,000

1,626,131,000

1,739,850,000

Management Service [Member]

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

Management Service [Member] | Segment Reconciling Items

(27,697,000)

(29,641,000)

(40,039,000)

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

Noncontrolling interest - property partnerships [Member]

27,697,000

29,641,000

40,039,000

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

Company's share of net operating income from joint ventures

186,304,000

162,887,000

183,989,000

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

$ 186,304,000

$ 162,887,000

$ 183,989,000

[1]

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 2,792,160	$ 2,678,795	$ 2,824,634
Rental Revenue: Residential	42,668	38,146	36,914
Rental Revenue Total	$ 2,848,437	$ 2,724,419	$ 2,910,137
Rental Revenue: % of Grand Totals	100.00%	100.00%	100.00%
Rental Expenses: Class A Office	$ 996,707	$ 998,469	$ 1,034,025
Rental Expenses: Residential	24,444	18,739	15,985
Rental Expenses: Total	$ 1,034,149	$ 1,030,344	$ 1,084,014
Rental Expenses: % Of Grand Totals	100.00%	100.00%	100.00%
Net Operating Income	$ 1,814,288	$ 1,694,075	$ 1,826,123
Net Operating Income: % of Grand Totals	100.00%	100.00%	100.00%
Company's Share of Net Operating Income: % of Grand Totals	100.00%	100.00%	100.00%
Segment Reconciling Items
Segment Reporting Information [Line Items]
Other revenue	$ (12,487)	$ (11,626)	$ (10,386)
Operating expense	(12,487)	(11,626)	(10,386)
Net Operating Income	(107,756)	(94,943)	(97,716)
Boston [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	930,560	897,915	895,098
Rental Revenue: Residential	13,397	13,616	13,786
Rental Revenue Total	$ 957,566	$ 919,009	$ 957,473
Rental Revenue: % of Grand Totals	33.62%	33.73%	32.90%
Rental Expenses: Class A Office	$ 322,298	$ 318,509	$ 322,282
Rental Expenses: Residential	5,811	5,378	5,071
Rental Expenses: Total	$ 341,107	$ 337,023	$ 361,357
Rental Expenses: % Of Grand Totals	32.98%	32.71%	33.34%
Net Operating Income	$ 16,551	$ 10,765	$ 5,494
Net Operating Income: % of Grand Totals	33.98%	34.35%	32.64%
Company's Share of Net Operating Income: % of Grand Totals	33.98%	33.88%	32.27%
Los Angeles [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 0	$ 0	$ 0
Rental Revenue: Residential	0	0	0
Rental Revenue Total	$ 0	$ 0	$ 0
Rental Revenue: % of Grand Totals	0.00%	0.00%	0.00%
Rental Expenses: Class A Office	$ 0	$ 0	$ 0
Rental Expenses: Residential	0	0	0
Rental Expenses: Total	$ 0	$ 0	$ 0
Rental Expenses: % Of Grand Totals	0.00%	0.00%	0.00%
Net Operating Income	$ 51,641	$ 57,907	$ 61,338
Net Operating Income: % of Grand Totals	0.00%	0.00%	0.00%
Company's Share of Net Operating Income: % of Grand Totals	2.98%	3.56%	3.53%
New York [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 1,012,172	$ 935,966	$ 1,011,912
Rental Revenue: Residential	0	0	0
Rental Revenue Total	$ 1,012,172	$ 935,966	$ 1,011,912
Rental Revenue: % of Grand Totals	35.53%	34.36%	34.78%
Rental Expenses: Class A Office	$ 379,267	$ 384,753	$ 389,532
Rental Expenses: Residential	0	0	0
Rental Expenses: Total	$ 379,267	$ 384,753	$ 389,532
Rental Expenses: % Of Grand Totals	36.67%	37.35%	35.93%
Net Operating Income	$ (664)	$ (5,326)	$ 4,174
Net Operating Income: % of Grand Totals	34.88%	32.54%	34.09%
Company's Share of Net Operating Income: % of Grand Totals	28.18%	26.12%	27.77%
San Francisco [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 508,620	$ 508,327	$ 533,189
Rental Revenue: Residential	3,892	155	0
Rental Revenue Total	$ 512,512	$ 508,482	$ 533,189
Rental Revenue: % of Grand Totals	17.99%	18.66%	18.32%
Rental Expenses: Class A Office	$ 168,040	$ 163,156	$ 177,994
Rental Expenses: Residential	6,717	2,261	0
Rental Expenses: Total	$ 174,757	$ 165,417	$ 177,994
Rental Expenses: % Of Grand Totals	16.90%	16.05%	16.42%
Net Operating Income	$ 14,152	$ 14,928	$ 0
Net Operating Income: % of Grand Totals	18.62%	20.25%	19.45%
Company's Share of Net Operating Income: % of Grand Totals	20.27%	22.02%	20.39%
Seattle
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 0
Rental Revenue: Residential	0
Rental Revenue Total	$ 0
Rental Revenue: % of Grand Totals	0.00%
Rental Expenses: Class A Office	$ 0
Rental Expenses: Residential	0
Rental Expenses: Total	$ 0
Rental Expenses: % Of Grand Totals	0.00%
Net Operating Income	$ 2,498
Net Operating Income: % of Grand Totals	0.00%
Company's Share of Net Operating Income: % of Grand Totals	0.14%
Washington, DC [Member]
Segment Reporting Information [Line Items]
Rental Revenue: Class A Office	$ 340,808	$ 336,587	$ 384,435
Rental Revenue: Residential	25,379	24,375	23,128
Rental Revenue Total	$ 366,187	$ 360,962	$ 407,563
Rental Revenue: % of Grand Totals	12.86%	13.25%	14.00%
Rental Expenses: Class A Office	$ 127,102	$ 132,051	$ 144,217
Rental Expenses: Residential	11,916	11,100	10,914
Rental Expenses: Total	$ 139,018	$ 143,151	$ 155,131
Rental Expenses: % Of Grand Totals	13.45%	13.89%	14.31%
Net Operating Income	$ 23,578	$ 16,669	$ 26,710
Net Operating Income: % of Grand Totals	12.52%	12.86%	13.82%
Company's Share of Net Operating Income: % of Grand Totals	14.45%	14.42%	16.04%
Hotel [Member]
Segment Reporting Information [Line Items]
Other revenue	$ 13,609	$ 7,478	$ 48,589
Operating expense	12,998	13,136	34,004
Hotel [Member] \| Boston [Member]
Segment Reporting Information [Line Items]
Other revenue	13,609	7,478	48,589
Operating expense	12,998	13,136	34,004
Hotel [Member] \| Los Angeles [Member]
Segment Reporting Information [Line Items]
Other revenue	0	0	0
Operating expense	0	0	0
Hotel [Member] \| New York [Member]
Segment Reporting Information [Line Items]
Other revenue	0	0	0
Operating expense	0	0	0
Hotel [Member] \| San Francisco [Member]
Segment Reporting Information [Line Items]
Other revenue	0	0	0
Operating expense	0	0	0
Hotel [Member] \| Seattle
Segment Reporting Information [Line Items]
Other revenue	0
Operating expense	0
Hotel [Member] \| Washington, DC [Member]
Segment Reporting Information [Line Items]
Other revenue	0	0	0
Operating expense	0	0	0
Noncontrolling interest - property partnerships [Member]
Segment Reporting Information [Line Items]
Net Operating Income	(186,304)	(162,887)	(183,989)
Noncontrolling interest - property partnerships [Member] \| Segment Reconciling Items
Segment Reporting Information [Line Items]
Net Operating Income	(186,304)	(162,887)	(183,989)
Noncontrolling interest - property partnerships [Member] \| Boston [Member]
Segment Reporting Information [Line Items]
Net Operating Income	(43,232)	(41,849)	(40,109)
Noncontrolling interest - property partnerships [Member] \| Los Angeles [Member]
Segment Reporting Information [Line Items]
Net Operating Income	0	0	0
Noncontrolling interest - property partnerships [Member] \| New York [Member]
Segment Reporting Information [Line Items]
Net Operating Income	(143,072)	(121,038)	(143,432)
Noncontrolling interest - property partnerships [Member] \| San Francisco [Member]
Segment Reporting Information [Line Items]
Net Operating Income	0	0	(448)
Noncontrolling interest - property partnerships [Member] \| Seattle
Segment Reporting Information [Line Items]
Net Operating Income	0
Noncontrolling interest - property partnerships [Member] \| Washington, DC [Member]
Segment Reporting Information [Line Items]
Net Operating Income	0	0	0
Company's Share [Member]
Segment Reporting Information [Line Items]
Net Operating Income	1,735,740	1,626,131	1,739,850
Company's Share [Member] \| Boston [Member]
Segment Reporting Information [Line Items]
Net Operating Income	589,778	550,902	561,501
Company's Share [Member] \| Los Angeles [Member]
Segment Reporting Information [Line Items]
Net Operating Income	51,641	57,907	61,338
Company's Share [Member] \| New York [Member]
Segment Reporting Information [Line Items]
Net Operating Income	489,169	424,849	483,122
Company's Share [Member] \| San Francisco [Member]
Segment Reporting Information [Line Items]
Net Operating Income	351,907	357,993	354,747
Company's Share [Member] \| Seattle
Segment Reporting Information [Line Items]
Net Operating Income	2,498
Company's Share [Member] \| Washington, DC [Member]
Segment Reporting Information [Line Items]
Net Operating Income	$ 250,747	$ 234,480	$ 279,142

Earnings Per Share / Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Redeemable Common Units	17,034,000	17,211,000	17,618,000
Basic Earnings:
Net income attributable to the company's common shareholders / unitholders	$ 561,993	$ 979,979	$ 580,102
Net income attributable to the company's common shareholders / unitholders (in shares / units)	173,150,000	172,643,000	172,200,000
Net income attributable to the company's common shareholders / unitholders (in dollars per share / unit)		$ 5.68
Allocation of undistributed earnings to participating securities		$ (830)
Allocation of undistributed earnings to participating securities (in shares / units)		0
Allocation of undistributed earnings to participating securities (in dollars per share / unit)		$ (0.01)
Net Income Available To Common Stockholders After Allocation of Undistributed Earnings to Participating Securities Basic	$ 561,993	$ 979,149	$ 580,102
Weighted Average Number Of Shares Outstanding After Allocation of Undistributed Earnings to Participating Securities Basic (in shares)	173,150,000	172,643,000	172,200,000
Earnings Per Share After Allocation of Undistributed Earnings to Participating Securities Basic (dollars per share)	$ 3.25	$ 5.67	$ 3.37
Effect of Dilutive Securities:
Stock Based Compensation	$ 0	$ 0	$ 0
Stock Based Compensation (in shares / units)	260,000	85,000	301,000
Weighted Average Number Diluted Shares Outstanding Adjustment (per share)	$ (0.01)	$ 0	$ (0.01)
Diluted Earnings:
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders	$ 561,993	$ 979,149	$ 580,102
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders (in shares / units)	173,410,000	172,728,000	172,501,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 3.24	$ 5.67	$ 3.36

Employee Benefits Plan (Details) - USD ($) $ in Thousands	12 Months Ended
Employee Benefits Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	200.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	3.00%
Defined Contribution Plan, Employer Matching Contribution, Eligible Earnings Limit by IRS Amount	$ 290	$ 285	$ 280
Defined Contribution Plan, Employer Discretionary Contribution Amount	4,700	4,000	$ 4,200
Separate Unrestricted Cash For Deferred Compensation Plan.	43,600	39,500
Deferred Compensation Liability, Current and Noncurrent	42,700	38,600
Officer [Member]
Defined Contribution Plan Disclosure [Line Items]
Separate Unrestricted Cash For Deferred Compensation Plan.	$ 42,700	$ 38,600

Stock Option and Incentive Plan (Narrative) (Details) - USD ($) $ in Millions					12 Months Ended
	May 20, 2021	Feb. 02, 2021	Feb. 06, 2020	Feb. 09, 2019	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period					4 years
MYLTIP 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards			$ 17.6
Final awards percentage of target			83.80%
Forfeitures, in units			270,942
MYLTIP 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards				$ 13.6
Final awards percentage of target				69.50%
Forfeitures, in units				364,980
MYLTIP 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award		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 peer 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.
Distributions percent before measurement date		10.00%
Vesting Period		3 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights		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.
Value of MYLTIP Awards		$ 15.3
2021 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Description	The material features of the 2021 Plan include, among other things: (i) the maximum number of shares of common stock reserved and available for issuance under the 2021 Plan is 5,400,000 shares less one share for every one share that was granted between March 4, 2021 and May 19, 2021 under the 2012 Plan, (ii) shares of common stock underlying awards granted under the 2021 Plan or the 2012 Plan that are forfeited, canceled or otherwise terminated (other than by exercise) will be added back to the shares of common stock available for issuance under the 2021 Plan and, with respect to “full-value” awards under the 2021 Plan or the 2012 Plan, shares tendered or held back for taxes and shares previously reserved for issuance pursuant to such an award to the extent that such shares are not issued and are no longer issuable pursuant to such an award (e.g., in the event that a full-value award that may be settled in cash or by issuance of shares of common stock is settled in cash) will be added back to the shares available for issuance under the 2021 Plan, (iii) the award of stock options (both incentive and non-qualified options), stock appreciation rights, restricted stock units, restricted stock, unrestricted stock, dividend equivalent rights, cash-based awards and other equity-based awards (including LTIP Units) is permitted, (iv) stock options may not be repriced and “underwater” stock options may not be exchanged for another award or cash without stockholder approval; and (v) the term of the 2021 Plan is for ten years from the date of stockholder approval.
Minimum [Member] \| MYLTIP 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance		0
Maximum [Member] \| MYLTIP 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance		352,021
Target \| MYLTIP 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance		176,009

Stock Option and Incentive Plan Stock and Units (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Feb. 05, 2021	Feb. 02, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued			156,623,749	155,797,725
Vesting Period			4 years
Stock based compensation expense			$ 49,700	$ 43,000	$ 39,800
Common Stock, Value, Issued			1,565	$ 1,557
Intrinsic Value of stock options			$ 1,900
Beginning outstanding, shares			103,641	351,561	395,353	540,441
Weighted Average Exercise Price			$ 97.01	$ 96.97	$ 96.37	$ 96.35
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued			57,383	29,630	26,503
LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value Of LTIP Units Issued			$ 23,800	$ 26,300	$ 22,100
Weighted average price (per unit)			$ 84.43	$ 127.14	$ 121.50
Expected life assumed to calculate per unit fair value per LTIP unit (in years)			5 years 8 months 12 days	5 years 8 months 12 days	5 years 8 months 12 days
Risk-free rate			0.65%	1.47%	2.68%
Expected price volatility			30.00%	18.00%	27.00%
Number of shares issued			281,640	207,181	181,919
MYLTIP 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued					220,734
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance			250,000
Employee discount			85.00%
Number of shares issued			9,846	7,195	5,862
Weighted Average Price of Shares Purchased			$ 89.73	$ 90.53	$ 104.11
stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted			0	0	0
MYLTIP 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Final awards percentage of target	29.20%
Value of MYLTIP Awards	$ 4,600
Forfeitures, in units	285,925
MYLTIP 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards		$ 15,300
Vesting Period		3 years
Number of shares issued			352,021
MYLTIP 2021 \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance		352,021
MYLTIP 2020 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued				203,278
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share)			$ 0.01
Common Stock, Value, Issued			$ 5,800	$ 4,000	$ 3,500
Common Stock Weighted Average Price (in dollars per share)			$ 100.60	$ 133.81	$ 131.27
LTIP and MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share)			$ 0.25
Ltips (including vested MYLTIPS) And Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses			$ 22,500
Unvested MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses			$ 7,400
Weighted-average period (years)			2 years

Stock Option Rollforward Table (Details) - $ / shares	12 Months Ended
Stock Option Rollforward Table (Details) - $ / shares	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Text Block [Abstract]
Beginning outstanding, shares	351,561	395,353	540,441
Exercised	(247,920)	(43,792)	(145,088)
Ending outstanding, shares	103,641	351,561	395,353
Beginning outstanding, Weighted-average Exercise Price	$ 96.97	$ 96.37	$ 96.35
Weighted Average Exercise Price	96.95	91.60	96.27
Ending outstanding, Weighted-average Exercise Price	$ 97.01	$ 96.97	$ 96.37

Stock Options Outstanding Table (Details) - $ / shares	12 Months Ended
Stock Options Outstanding Table (Details) - $ / shares	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning outstanding, shares	103,641	351,561	395,353	540,441
Weighted Average Exercise Price	$ 97.01	$ 96.97	$ 96.37	$ 96.35
Exercise price $95.69
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning outstanding, shares	54,282
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	1 year 3 months 18 days
Weighted Average Exercise Price	$ 95.69
Number Exercisable	54,282
Exercisable, Weighted Average Exercise Price	$ 95.69
Exercise Price $98.46
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning outstanding, shares	49,359
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	1 year 1 month 6 days
Weighted Average Exercise Price	$ 98.46
Number Exercisable	49,359
Exercisable, Weighted Average Exercise Price	$ 98.46

Related Party Transactions (Details) $ in Thousands	12 Months Ended
Related Party Transactions (Details) $ in Thousands	Dec. 31, 2021 USD ($) ft² nonemployeedirectors shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)	Dec. 16, 2021 shares
Related Party Transaction [Line Items]
Related party note receivable, net	$ 78,336	$ 77,552
Interest and Other Income	$ 5,704	5,953	$ 18,939
Number Of Non Employee Directors Electing To Receive Deferred Stock Units \| nonemployeedirectors	7
Separate Unrestricted Cash For Deferred Compensation Plan.	$ 43,600	39,500
Liability for directors	$ 320,775	$ 336,264
Common stock, shares issued \| shares	156,623,749	155,797,725
Reedemable deferred stock units, units \| shares	83,073	72,966
Three Hudson Boulevard [Member]
Related Party Transaction [Line Items]
Net Rentable Area (in sf) \| ft²	2,000,000
Ownership Percentage	25.00%
Related party note receivable, net	$ 80,000
Loans Receivable, Basis Spread on Variable Rate	3.50%
Interest and Other Income	$ 3,600	$ 2,700	2,500
Director Cessation Member [Member]
Related Party Transaction [Line Items]
Common stock, shares issued \| shares				498
Director
Related Party Transaction [Line Items]
Separate Unrestricted Cash For Deferred Compensation Plan.	900	800
Liability for directors	900	800
Immediate Family Member of Management or Principal Owner
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	0	914	21
Real Estate Brokerage Firm
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 1,900	$ 3,400	$ 2,600

Subsequent Events (Details) $ in Millions			12 Months Ended
Subsequent Events (Details) $ in Millions	Feb. 04, 2022 USD ($) shares	Feb. 01, 2022 USD ($) shares	Dec. 31, 2021 shares	Dec. 31, 2020 shares	Dec. 31, 2019 shares	Feb. 02, 2022 ft²	Jan. 28, 2022 shares	Jan. 18, 2022 ft²
Subsequent Event [Line Items]
Common stock, shares issued			156,623,749	155,797,725
Restricted Stock [Member]
Subsequent Event [Line Items]
Common stock, shares issued			57,383	29,630	26,503
LTIP Units [Member]
Subsequent Event [Line Items]
Number of shares issued			281,640	207,181	181,919
MYLTIP 2019 [Member]
Subsequent Event [Line Items]
Number of shares issued					220,734
Subsequent Event [Member] \| 651 Gateway
Subsequent Event [Line Items]
Ownership Percentage								50.00%
Subsequent Event [Member] \| 651 Gateway \| Construction
Subsequent Event [Line Items]
Net Rentable Area (in sf) \| ft²								293,000
Subsequent Event [Member] \| Platform 16
Subsequent Event [Line Items]
Ownership Percentage						55.00%
Subsequent Event [Member] \| Platform 16 \| Scenario, Plan
Subsequent Event [Line Items]
Net Rentable Area (in sf) \| ft²						1,100,000
Subsequent Event [Member] \| Platform 16 \| Construction
Subsequent Event [Line Items]
Net Rentable Area (in sf) \| ft²						390,000
Subsequent Event [Member] \| Restricted Stock [Member]
Subsequent Event [Line Items]
Common stock, shares issued							33,091
Subsequent Event [Member] \| LTIP Units [Member]
Subsequent Event [Line Items]
Number of shares issued		249,873
Subsequent Event [Member] \| MYLTIP 2022
Subsequent Event [Line Items]
Minimum earned awards		0
Maximum Earned Awards		254,061
Earned awards - Target		127,031
Value of MYLTIP Awards \| $		$ 17.3
Subsequent Event [Member] \| MYLTIP 2019 [Member]
Subsequent Event [Line Items]
Value of MYLTIP Awards \| $	$ 8.6
Final awards percentage of target	69.00%
Forfeitures, in units	144,043

SEC Schedule, Article 12-28, Real Estate and Accumulated Depreciation (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2021

May 19, 2021

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

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

Encumbrances

^[1]

$ 3,267,914

5,238,614

13,216,859

5,279,360

^[2]

5,348,929

^[3]

16,931,377

^[4]

560,355

$ 450,954

894,172

868,773

23,734,833

22,926,494

$ 22,449,476

$ 21,207,189

Furniture, Fixtures and Equipment

5,736,240

5,396,111

$ 5,135,289

$ 4,773,800

51,695

49,606

Aggregate cost for tax purpose

24,200,000

Real Estate Aggregate Accumulated Depreciation For Tax Purposes

5,400,000

Debt Issuance Costs, Net

(32,100)

248,900

$ 22,300

$ 22,500

Maximum [Member]

Real Estate and Accumulated Depreciation, Life Used for Depreciation

40 years

Furniture, fixtures, and equipment

Accumulated Depreciation Related to Furniture, Fixtures and Equipment

$ 35,778

Land and Land Improvements [Member]

214,165

Buildings and improvements

169,778

767Fifth Avenue (the General Motors Building) | Office Building [Member]

23,342

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

Encumbrances

2,281,016

1,796,252

1,532,654

260,700

1,796,252

1,793,354

3,589,606

$ 407,377

Prudential Center | Office Building [Member]

^[5]

(1)

$ 92,077

948,357

556,917

100,539

1,439,107

192

57,513

1,597,351

$ 660,321

Embarcadero Center | Office Building [Member]

^[5]

(1)

$ 179,697

847,410

418,084

180,420

1,264,771

1,445,191

$ 673,363

399 Park Avenue | Office Building [Member]

^[5]

(1)

$ 339,200

700,358

306,841

339,200

1,007,199

1,346,399

$ 387,131

601 Lexington Avenue | Office Building [Member]

^[5]

(1)

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

Encumbrances

$ 986,898

241,600

494,782

448,942

279,281

906,043

1,185,324

$ 314,209

Salesforce Tower | Office Building [Member]

^[5]

(1)

$ 200,349

946,205

7,515

200,349

953,720

1,154,069

$ 99,152

200 Clarendon Street and Garage | Office Building [Member]

^[5]

(1)

$ 219,543

667,884

222,640

250,560

859,507

1,110,067

$ 277,388

250 West 55th Street | Office Building [Member]

^[5]

(1)

$ 285,263

603,167

52,298

285,263

655,465

940,728

$ 159,238

100 Federal Street | Office Building [Member]

^[5]

(1)

$ 131,067

435,954

138,727

131,067

574,681

705,748

$ 157,939

Times Square Tower | Office Building [Member]

^[5]

(1)

$ 165,413

380,438

77,864

159,694

464,021

623,715

$ 220,676

Carnegie Center | Office Building [Member]

^[5]

(1)

$ 142,666

316,856

144,387

90,498

457,995

55,416

603,909

$ 232,183

Atlantic Wharf | Office Building [Member]

^[5]

(1)

$ 63,988

454,537

19,831

63,988

474,368

538,356

$ 156,879

599 Lexington Avenue | Office Building [Member]

^[5]

(1)

$ 81,040

100,507

219,759

81,040

320,266

401,306

$ 171,713

Fountain Square | Office Building [Member]

^[5]

(1)

$ 56,853

306,298

29,595

56,853

335,893

392,746

$ 94,501

510 Madison Avenue | Office Building [Member]

^[5]

(1)

$ 103,000

253,665

28,825

103,000

282,490

385,490

$ 90,673

680 Folsom Street | Office Building [Member]

^[5]

(1)

$ 72,545

219,766

8,026

72,545

227,792

300,337

$ 63,864

145 Broadway | Office Building [Member]

^[5]

(1)

$ 121

273,013

25,789

23,164

275,759

298,923

$ 18,393

2200 Pennsylvania Avenue | Office Building [Member]

^[5]

(1)

$ 0

183,541

110,980

105,787

188,734

294,521

$ 71,983

South of Market and Democracy Tower | Office Building [Member]

^[5]

(1)

$ 13,603

237,479

21,546

13,603

259,025

272,628

$ 94,269

601 Massachusetts Avenue | Office Building [Member]

^[5]

(1)

$ 95,310

165,173

3,953

95,310

169,126

264,436

$ 36,983

Bay Colony Corporate Center | Office Building [Member]

^[5]

(1)

$ 18,789

148,451

80,753

18,789

229,144

247,993

$ 97,149

535 Mission Street | Office Building [Member]

^[5]

(1)

$ 40,933

148,378

3,501

40,933

151,879

192,812

$ 37,477

Mountain View Research Park | Office Building [Member]

^[5]

(1)

$ 95,066

68,373

16,801

95,066

85,174

180,240

$ 24,149

Reservoir Place | Office Building [Member]

^[5]

(1)

$ 18,605

104,124

49,870

19,089

153,219

291

172,599

$ 78,109

1330 Connecticut Avenue | Office Building [Member]

^[5]

(1)

$ 25,982

82,311

32,548

25,982

114,859

140,841

$ 41,783

One Freedom Square | Office Building [Member]

^[5]

(1)

$ 9,929

84,504

36,341

9,883

120,891

130,774

$ 58,850

Kingstowne Towne Center | Office Building [Member]

^[5]

(1)

$ 18,021

109,038

3,711

18,021

112,749

130,770

$ 49,433

One and Two Reston Overlook | Office Building [Member]

^[5]

(1)

$ 16,456

66,192

36,276

15,074

103,850

118,924

$ 54,155

140 Kendrick Street | Office Building [Member]

^[5]

(1)

$ 18,095

66,905

33,823

18,095

100,728

118,823

$ 39,039

Shady Grove Innovation District [Member] | Office Building [Member]

^[5]

(1)

$ 52,030

64,212

2,676

26,834

34,974

57,110

118,918

$ 1,048

Weston Corporate Center | Office Building [Member]

^[5]

(1)

$ 25,753

92,312

25,854

92,243

118,097

$ 35,329

17Fifty Presidents Street | Office Building [Member]

^[5]

(1)

$ 0

113,362

113,406

113,406

$ 7,840

Discovery Square | Office Building [Member]

^[5]

(1)

$ 11,198

71,782

15,759

11,146

87,593

98,739

$ 48,686

355 Main Street | Office Building [Member]

^[5]

(1)

$ 18,863

53,346

24,697

21,098

75,808

96,906

$ 31,739

10 CityPoint | Office Building [Member]

^[5]

(1)

$ 1,953

85,752

6,800

2,127

92,378

94,505

$ 17,327

Two Freedom Square | Office Building [Member]

^[5]

(1)

$ 13,930

77,739

(6,396)

13,866

71,407

85,273

$ 31,823

90 Broadway | Office Building [Member]

^[5]

(1)

$ 19,104

52,078

18,697

20,741

69,138

89,879

$ 26,749

153 & 211 Second Avenue [Member] | Office Building [Member]

^[5]

(1)

$ 33,233

55,940

33,233

55,940

89,173

$ 1,819

230 CityPoint | Office Building [Member]

^[5]

(1)

$ 13,189

49,823

22,257

13,403

71,866

85,269

$ 34,984

77 CityPoint | Office Building [Member]

^[5]

(1)

$ 13,847

60,383

11,419

13,997

71,652

85,649

$ 31,804

20 Citypoint | Office Building [Member]

^[5]

(1)

$ 4,887

72,764

7,071

4,887

79,835

84,722

$ 6,135

Waltham Weston Corporate Center | Office Building [Member]

^[5]

(1)

$ 10,385

60,694

9,675

10,350

70,404

80,754

$ 39,353

200 West Street | Office Building [Member]

^[5]

(1)

$ 16,148

24,983

36,931

16,148

61,597

317

78,062

$ 18,922

^[5]

(1)

Sumner Square

Sumner Square | Office Building [Member]

$ 27,100

$ 624

28,745

47,265

28,028

48,606

76,634

$ 29,247

2440 West El Camino Real | Office Building [Member]

^[5]

(1)

$ 16,741

51,285

6,290

16,741

57,575

74,316

$ 17,265

300 Binney Street | Office Building [Member]

^[5]

(1)

$ 18,080

51,262

140

18,080

51,402

69,482

$ 14,537

Reston Corporate Center | Office Building [Member]

^[5]

(1)

$ 9,135

50,857

3,625

9,496

54,121

63,617

$ 32,162

Wisconsin Place | Office Building [Member]

^[5]

(1)

$ 0

53,349

12,600

65,949

65,949

$ 28,025

255 Main Street | Office Building [Member]

^[5]

(1)

$ 134

25,110

32,604

134

57,714

57,848

$ 39,294

University Place | Office Building [Member]

^[5]

(1)

$ 0

37,091

15,062

6,004

46,149

52,153

$ 32,504

890 Winter Street | Office Building [Member]

^[5]

(1)

$ 13,913

28,557

4,745

13,913

33,302

47,215

$ 3,928

Capital Gallery | Office Building [Member]

^[5]

(1)

$ 4,725

29,565

5,018

6,128

33,180

39,308

$ 20,706

North First Business Park | Office Building [Member]

^[5]

(1)

$ 23,398

13,069

4,522

23,371

17,618

40,989

$ 17,011

150 Broadway | Office Building [Member]

^[5]

(1)

$ 850

25,042

345

822

25,415

26,237

$ 14,225

105 Broadway | Office Building [Member]

^[5]

(1)

$ 1,299

12,943

10,617

1,868

22,991

24,859

$ 13,674

Lexington Office Park | Office Building [Member]

^[5]

(1)

$ 998

1,426

17,818

1,073

18,978

191

20,242

$ 15,785

The Point | Office Building [Member]

^[5]

(1)

$ 6,395

10,040

421

6,492

10,364

16,856

$ 1,984

690 Folsom Street | Office Building [Member]

^[5]

(1)

$ 3,219

11,038

1,877

3,219

12,915

16,134

$ 3,354

195 West Street | Office Building [Member]

^[5]

(1)

$ 1,611

6,652

6,481

1,611

13,133

14,744

$ 8,540

33 Hayden Avenue | Office Building [Member]

^[5]

(1)

$ 266

3,234

10,864

266

14,098

14,364

$ 6,576

92-100 Hayden Avenue | Office Building [Member]

^[5]

(1)

$ 594

6,748

5,530

619

12,253

12,872

$ 11,247

7501 Boston Boulevard, Building Seven | Office Building [Member]

^[5]

(1)

$ 665

9,273

314

665

9,587

10,252

$ 5,783

7435 Boston Boulevard, Building One | Office Building [Member]

^[5]

(1)

$ 392

3,822

4,323

486

8,051

8,537

$ 6,802

32 Hartwell Avenue | Office Building [Member]

^[5]

(1)

$ 168

1,943

6,358

168

8,301

8,469

$ 2,557

7450 Boston Boulevard, Building Three | Office Building [Member]

^[5]

(1)

$ 1,165

4,681

2,199

1,327

6,718

8,045

$ 4,646

250 Binney Street | Office Building [Member]

^[5]

(1)

$ 110

4,483

2,939

110

7,422

7,532

$ 6,399

8000 Grainger Court Building Five | Office Building [Member]

^[5]

(1)

$ 366

4,282

2,604

453

6,799

7,252

$ 5,916

453 Ravendale Drive | Office Building [Member]

^[5]

(1)

$ 5,477

1,090

676

5,477

1,766

7,243

$ 924

7300 Boston Boulevard Building Thirteen | Office Building [Member]

^[5]

(1)

$ 608

4,773

863

608

5,636

6,244

$ 2,463

17 Hartwell Avenue | Office Building [Member]

^[5]

(1)

$ 26

150

5,921

6,071

6,097

$ 2,961

7601 Boston Boulevard Building Eight | Office Building [Member]

^[5]

(1)

$ 200

878

4,352

378

5,052

5,430

$ 4,778

7500 Boston Boulevard Building Six | Office Building [Member]

^[5]

(1)

$ 138

3,749

1,181

234

4,834

5,068

$ 4,376

8000 Corporate Court Building Eleven | Office Building [Member]

^[5]

(1)

$ 136

3,071

1,552

686

4,073

4,759

$ 3,346

7375 Boston Boulevard Building Ten | Office Building [Member]

^[5]

(1)

$ 23

2,685

824

3,485

3,532

$ 2,790

7451 Boston Boulevard Building Two | Office Building [Member]

^[5]

(1)

$ 249

1,542

1,545

535

2,801

3,336

$ 2,711

7374 Boston Boulevard Building Four | Office Building [Member]

^[5]

(1)

$ 241

1,605

1,281

303

2,824

3,127

$ 2,675

The Skylyne | Residential Building

^[5]

(1)

$ 28,962

239,077

1,097

28,962

240,174

269,136

$ 8,132

Signature at Reston | Residential Building

^[5]

(1)

$ 27,076

190,580

838

27,076

191,418

218,494

$ 18,534

Proto Kendall Square | Residential Building

^[5]

(1)

$ 9,243

127,248

3,336

9,245

130,582

139,827

$ 11,195

The Avant at Reston Town Center | Residential Building

^[5]

(1)

$ 20,350

91,995

846

20,350

92,841

113,191

$ 19,681

The Lofts at Atlantic Wharf | Residential Building

^[5]

(1)

$ 3,529

54,891

2,215

3,529

57,106

60,635

$ 15,689

Boston Cambridge Marriott | Hotel [Member]

^[5]

(1)

$ 478

37,918

32,226

478

70,144

70,622

$ 50,729

Kendall Center Green Garage | Garage

^[5]

(1)

$ 0

35,035

6,432

41,467

41,467

$ 15,695

Kendall Center Yellow Garage | Garage

^[5]

(1)

$ 1,256

15,697

840

1,256

16,537

17,793

$ 6,727

Kendall Center Blue Garage | Garage

^[5]

(1)

$ 1,163

11,633

446

1,163

12,079

13,242

$ 9,900

Reston Next | Development

^[5]

(1)

$ 0

514,182

2,901

250,135

261,146

514,182

$ 1,631

2100 Pennsylvania Avenue | Development

N/A

$ 0

393,094

185,203

207,891

393,094

$ 5,941

325 Main Street | Development

N/A

$ 174

285,807

772

285,209

285,981

$ 0

880 Winter Street [Member] | Development

N/A

$ 15,597

37,255

(667)

15,597

19,614

16,974

52,185

$ 1,247

180 CityPoint | Development

N/A

$ 0

50,776

50,776

50,776

$ 0

N/A

180 CityPoint | Land

$ 0

50,776

50,776

$ 50,776

103 CityPoint | Development

N/A

$ 0

14,663

14,663

14,663

$ 0

N/A

103 CityPoint | Land

$ 0

14,663

14,663

$ 14,663

777 Harrison Street | Land

N/A

$ 144,647

26,800

171,400

171,447

$ 11

3625 - 3635 Peterson Way | Office Building [Member]

N/A

$ 63,206

4,541

67,747

$ 67,747

3625 - 3635 Peterson Way | Land

^[6]

N/A

$ 63,206

4,541

67,747

67,747

$ 0

Back Bay Station Master Plan | Land

N/A

$ 0

53,432

53,432

53,432

$ 0

North First Master Plan | Land

N/A

$ 35,004

3,941

38,945

38,945

$ 0

N/A

Plaza at Almaden | Land

$ 0

37,418

37,418

37,418

$ 0

Reston Gateway Master Plan | Land

N/A

$ 0

30,945

30,945

30,945

$ 0

Springfield Metro Center | Land

N/A

$ 0

19,887

19,887

19,887

$ 0

CityPoint South Master Plan | Land

N/A

$ 0

14,890

14,890

14,890

$ 0

Kendall Center Master Plan | Land

N/A

$ 0

8,381

8,381

8,381

$ 0

Broad Run Business Park | Land

N/A

$ 0

2,405

2,405

2,405

$ 0

N/A

Weston Quarry | Land

$ 0

1,249

1,249

1,249

$ 0

Reston Overlook Master Plan | Land

N/A

$ 0

$ 0

N/A

[1]	Includes unamortized deferred financing costs totaling approximately $(32.1) million.
[2]	Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $214,165 and $169,778, respectively.
[3]	Includes Right of Use Assets - Finance Leases of approximately $23,342.
[4]	Includes pre-development costs.
[5]	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.
[6]	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.

SEC Schedule, Article 12-28, Real Estate and Accumulated Depreciation Roll Forward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]
Balance at the beginning of the year	$ 22,926,494	$ 22,449,476	$ 21,207,189
Additions to / improvements of real estate	1,145,084	996,989	1,671,898
Assets sold/written-off	(336,745)	(519,971)	(429,611)
Balance at the end of the year	23,734,833	22,926,494	22,449,476
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Balance at the beginning of the year	5,396,111	5,135,289	4,773,800
Depreciation expense	615,553	566,813	557,130
Assets sold/written-off	(275,424)	(305,991)	(195,641)
Balance at the end of the year	$ 5,736,240	$ 5,396,111	$ 5,135,289

Label

Element

Value

bxp_RightOfUseAssetFinanceLeaseDeconsolidated

$ 0

bxp_RightOfUseAssetFinanceLeaseDeconsolidated

bxp_RightOfUseAssetFinanceLeaseDeconsolidated

(135,004,000)

bxp_RightOfUseAssetFinanceLeaseDeconsolidated

bxp_RightOfUseAssetFinanceLeaseDeconsolidated

bxp_RightOfUseAssetFinanceLeaseDeconsolidated

(135,004,000)

bxp_Leaseliabilityfinanceleasedeconsolidation

bxp_Leaseliabilityfinanceleasedeconsolidation

bxp_Leaseliabilityfinanceleasedeconsolidation

(119,534,000)

bxp_Leaseliabilityfinanceleasedeconsolidation

bxp_Leaseliabilityfinanceleasedeconsolidation

Payments for (Proceeds from) Other Real Estate Partnerships

bxp_Leaseliabilityfinanceleasedeconsolidation

(119,534,000)

us-gaap_PaymentsForProceedsFromOtherRealEstatePartnerships

Payments for (Proceeds from) Other Real Estate Partnerships

us-gaap_PaymentsForProceedsFromOtherRealEstatePartnerships

Payments for (Proceeds from) Other Real Estate Partnerships

us-gaap_PaymentsForProceedsFromOtherRealEstatePartnerships

24,112,000

Payments for (Proceeds from) Other Real Estate Partnerships

us-gaap_PaymentsForProceedsFromOtherRealEstatePartnerships

Payments for (Proceeds from) Other Real Estate Partnerships

us-gaap_PaymentsForProceedsFromOtherRealEstatePartnerships

Payments for (Proceeds from) Other Real Estate Partnerships

us-gaap_PaymentsForProceedsFromOtherRealEstatePartnerships

24,112,000

us-gaap_TransferToInvestments

107,132,000

us-gaap_TransferToInvestments

347,898,000

us-gaap_TransferToInvestments

29,246,000

us-gaap_TransferToInvestments

107,132,000

us-gaap_TransferToInvestments

347,898,000

us-gaap_TransferToInvestments

29,246,000

us-gaap_PaymentsToAcquireLoansReceivable

us-gaap_PaymentsToAcquireLoansReceivable

9,800,000

us-gaap_PaymentsToAcquireLoansReceivable

us-gaap_PaymentsToAcquireLoansReceivable

us-gaap_PaymentsToAcquireLoansReceivable

9,800,000

us-gaap_PaymentsToAcquireLoansReceivable

us-gaap_ProceedsFromMortgageDeposits

10,035,000

us-gaap_ProceedsFromMortgageDeposits

6,397,000

us-gaap_ProceedsFromMortgageDeposits

(3,544,000)

us-gaap_ProceedsFromMortgageDeposits

10,035,000

us-gaap_ProceedsFromMortgageDeposits

6,397,000

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

us-gaap_ProceedsFromMortgageDeposits

$ 3,544,000

us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock


	Year ended December 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	$	496,223	156,116	$	3.18
Effect of Dilutive Securities:
Stock Based Compensation	—		260	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,223	156,376	$	3.17

	Year ended December 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	$	862,227	155,432	$	5.55
Allocation of undistributed earnings to participating securities	(748)		—	(0.01)
Net income attributable to Boston Properties, Inc. common shareholders	$	861,479	155,432	$	5.54
Effect of Dilutive Securities:
Stock Based Compensation	—		85	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	861,479	155,517	$	5.54

	Year ended December 31, 2019
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:


Net income attributable to Boston Properties, Inc. common shareholders	$	511,034	154,582	$	3.31
Effect of Dilutive Securities:
Stock Based Compensation	—		301	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	511,034	154,883	$	3.30

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

us-gaap_ScheduleOfEarningsPerShareBasicAndDilutedTableTextBlock

Included in the number of units (the denominator) below are approximately 17,034,000, 17,211,000 and 17,618,000 redeemable common units for the years ended December 31, 2021, 2020 and 2019, respectively.


	Year ended December 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	$	561,993	173,150	$	3.25
Effect of Dilutive Securities:
Stock Based Compensation	—		260	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	561,993	173,410	$	3.24

	Year ended December 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	$	979,979	172,643	$	5.68
Allocation of undistributed earnings to participating securities	(830)		—	(0.01)
Net income attributable to Boston Properties Limited Partnership common unitholders	$	979,149	172,643	$	5.67
Effect of Dilutive Securities:
Stock Based Compensation	—		85	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	979,149	172,728	$	5.67


	Year ended December 31, 2019
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:


Net income attributable to Boston Properties Limited Partnership common unitholders	$	580,102	172,200	$	3.37
Effect of Dilutive Securities:
Stock Based Compensation	—		301	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	580,102	172,501	$	3.36

us-gaap_PaymentsToAcquireMarketableSecurities

$ (1,451,000)

us-gaap_PaymentsToAcquireMarketableSecurities

(2,551,000)

us-gaap_PaymentsToAcquireMarketableSecurities

2,132,000

us-gaap_PaymentsToAcquireMarketableSecurities

(1,451,000)

us-gaap_PaymentsToAcquireMarketableSecurities

(2,551,000)

Net Cash Provided by (Used in) Investing Activities

us-gaap_PaymentsToAcquireMarketableSecurities

2,132,000

us-gaap_NetCashProvidedByUsedInInvestingActivities

(1,039,956,000)

Net Cash Provided by (Used in) Investing Activities

us-gaap_NetCashProvidedByUsedInInvestingActivities

(613,719,000)

Net Cash Provided by (Used in) Investing Activities

us-gaap_NetCashProvidedByUsedInInvestingActivities

(1,015,091,000)

Net Cash Provided by (Used in) Investing Activities

us-gaap_NetCashProvidedByUsedInInvestingActivities

(1,039,956,000)

Net Cash Provided by (Used in) Investing Activities

us-gaap_NetCashProvidedByUsedInInvestingActivities

(613,719,000)

Net Cash Provided by (Used in) Investing Activities

us-gaap_NetCashProvidedByUsedInInvestingActivities

(1,015,091,000)

bxp_MortgageNotesPayableDeconsolidated

(198,381,000)

bxp_MortgageNotesPayableDeconsolidated

bxp_MortgageNotesPayableDeconsolidated

bxp_MortgageNotesPayableDeconsolidated

(198,381,000)

bxp_MortgageNotesPayableDeconsolidated

bxp_MortgageNotesPayableDeconsolidated

us-gaap_ProceedsFromSecuredNotesPayable

1,201,388,000

us-gaap_ProceedsFromSecuredNotesPayable

us-gaap_ProceedsFromSecuredNotesPayable

us-gaap_ProceedsFromSecuredNotesPayable

1,201,388,000

us-gaap_ProceedsFromSecuredNotesPayable

us-gaap_ProceedsFromSecuredNotesPayable

us-gaap_DepreciationDepletionAndAmortization

717,336,000

us-gaap_DepreciationDepletionAndAmortization

683,751,000

us-gaap_DepreciationDepletionAndAmortization

677,764,000

us-gaap_DepreciationDepletionAndAmortization

669,956,000

us-gaap_DepreciationDepletionAndAmortization

709,035,000

Conversions of noncontrolling interests to Stockholders' Equity

us-gaap_DepreciationDepletionAndAmortization

676,666,000

bxp_ConversionsOfNoncontrollingInterestsToStockholdersEquity

18,386,000

Conversions of noncontrolling interests to Stockholders' Equity

bxp_ConversionsOfNoncontrollingInterestsToStockholdersEquity

29,698,000

Conversions of noncontrolling interests to Stockholders' Equity

bxp_ConversionsOfNoncontrollingInterestsToStockholdersEquity

4,885,000

Conversions of noncontrolling interests to Stockholders' Equity

bxp_ConversionsOfNoncontrollingInterestsToStockholdersEquity

18,386,000

Conversions of noncontrolling interests to Stockholders' Equity

bxp_ConversionsOfNoncontrollingInterestsToStockholdersEquity

29,698,000

Conversions of noncontrolling interests to Stockholders' Equity

bxp_ConversionsOfNoncontrollingInterestsToStockholdersEquity

4,885,000

Issuance Of Restricted Units To Employees And Directors

bxp_IssuanceOfRestrictedUnitsToEmployeesAndDirectors

44,405,000

Issuance Of Restricted Units To Employees And Directors

bxp_IssuanceOfRestrictedUnitsToEmployeesAndDirectors

42,607,000

Issuance Of Restricted Units To Employees And Directors

bxp_IssuanceOfRestrictedUnitsToEmployeesAndDirectors

37,622,000

Amortization of right of use asset - operating leases

bxp_Amortizationofrightofuseassetoperatingleases

3,516,000

Amortization of right of use asset - operating leases

bxp_Amortizationofrightofuseassetoperatingleases

2,234,000

Amortization of right of use asset - operating leases

bxp_Amortizationofrightofuseassetoperatingleases

2,412,000

Amortization of right of use asset - operating leases

bxp_Amortizationofrightofuseassetoperatingleases

3,516,000

Amortization of right of use asset - operating leases

bxp_Amortizationofrightofuseassetoperatingleases

2,234,000

Amortization of right of use asset - operating leases

bxp_Amortizationofrightofuseassetoperatingleases

2,412,000

bxp_Writeoffoffullydepreciatedrealestate

239,317,000

bxp_Writeoffoffullydepreciatedrealestate

99,494,000

bxp_Writeoffoffullydepreciatedrealestate

129,831,000

bxp_Writeoffoffullydepreciatedrealestate

238,003,000

bxp_Writeoffoffullydepreciatedrealestate

99,494,000

bxp_Writeoffoffullydepreciatedrealestate

129,253,000

us-gaap_RepaymentsOfLinesOfCredit

625,000,000

us-gaap_RepaymentsOfLinesOfCredit

265,000,000

us-gaap_RepaymentsOfLinesOfCredit

380,000,000

us-gaap_RepaymentsOfLinesOfCredit

625,000,000

us-gaap_RepaymentsOfLinesOfCredit

265,000,000

us-gaap_RepaymentsOfLinesOfCredit

380,000,000

us-gaap_CapitalExpendituresIncurredButNotYetPaid

25,183,000

us-gaap_CapitalExpendituresIncurredButNotYetPaid

19,848,000

us-gaap_CapitalExpendituresIncurredButNotYetPaid

(89,245,000)

us-gaap_CapitalExpendituresIncurredButNotYetPaid

25,183,000

us-gaap_CapitalExpendituresIncurredButNotYetPaid

19,848,000

us-gaap_CapitalExpendituresIncurredButNotYetPaid

(89,245,000)

us-gaap_ProceedsFromOtherDebt

(500,000,000)

us-gaap_ProceedsFromOtherDebt

us-gaap_ProceedsFromOtherDebt

us-gaap_ProceedsFromOtherDebt

(500,000,000)

us-gaap_ProceedsFromOtherDebt

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

us-gaap_ProceedsFromOtherDebt

us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability

26,887,000

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability

287,540,000

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability

26,887,000

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability

Right-of-Use Asset Obtained in Exchange for Operating Lease Liability

us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability

287,540,000

Payments for Repurchase of Redeemable Preferred Stock

us-gaap_PaymentsForRepurchaseOfRedeemablePreferredStock

200,000,000

Payments for Repurchase of Redeemable Preferred Stock

us-gaap_PaymentsForRepurchaseOfRedeemablePreferredStock

Payments for Repurchase of Redeemable Preferred Stock

us-gaap_PaymentsForRepurchaseOfRedeemablePreferredStock

Payments for Repurchase of Redeemable Preferred Stock

us-gaap_PaymentsForRepurchaseOfRedeemablePreferredStock

200,000,000

Payments for Repurchase of Redeemable Preferred Stock

us-gaap_PaymentsForRepurchaseOfRedeemablePreferredStock

Payments for Repurchase of Redeemable Preferred Stock

us-gaap_PaymentsForRepurchaseOfRedeemablePreferredStock

bxp_Prepaidrentreclassifiedtorightofuseasset

bxp_Prepaidrentreclassifiedtorightofuseasset

bxp_Prepaidrentreclassifiedtorightofuseasset

15,000,000

bxp_Prepaidrentreclassifiedtorightofuseasset

bxp_Prepaidrentreclassifiedtorightofuseasset

bxp_Prepaidrentreclassifiedtorightofuseasset

15,000,000

bxp_Accruedrentalincomenetdeconsolidated

bxp_Accruedrentalincomenetdeconsolidated

4,558,000

bxp_Accruedrentalincomenetdeconsolidated

bxp_Accruedrentalincomenetdeconsolidated

bxp_Accruedrentalincomenetdeconsolidated

4,558,000

bxp_Accruedrentalincomenetdeconsolidated

us-gaap_FinanceLeasePrincipalPayments

1,250,000

us-gaap_FinanceLeasePrincipalPayments

us-gaap_FinanceLeasePrincipalPayments

502,000

us-gaap_FinanceLeasePrincipalPayments

1,250,000

us-gaap_FinanceLeasePrincipalPayments

us-gaap_FinanceLeasePrincipalPayments

(502,000)

bxp_TransferOfTenantLeaseCostsRealEstate

bxp_TransferOfTenantLeaseCostsRealEstate

3,462,000

bxp_TransferOfTenantLeaseCostsRealEstate

bxp_TransferOfTenantLeaseCostsRealEstate

bxp_TransferOfTenantLeaseCostsRealEstate

3,462,000

bxp_TransferOfTenantLeaseCostsRealEstate

us-gaap_PaymentsOfFinancingCosts

20,757,000

us-gaap_PaymentsOfFinancingCosts

10,416,000

us-gaap_PaymentsOfFinancingCosts

13,213,000

us-gaap_PaymentsOfFinancingCosts

20,757,000

us-gaap_PaymentsOfFinancingCosts

10,416,000

us-gaap_PaymentsOfFinancingCosts

13,213,000

us-gaap_TransferOfOtherRealEstate

us-gaap_TransferOfOtherRealEstate

111,889,000

us-gaap_TransferOfOtherRealEstate

12,767,000

us-gaap_TransferOfOtherRealEstate

us-gaap_TransferOfOtherRealEstate

111,889,000

us-gaap_TransferOfOtherRealEstate

12,767,000

us-gaap_PaymentsOfDebtIssuanceCosts

(16,186,000)

us-gaap_PaymentsOfDebtIssuanceCosts

us-gaap_PaymentsOfDebtIssuanceCosts

us-gaap_PaymentsOfDebtIssuanceCosts

(16,186,000)

us-gaap_PaymentsOfDebtIssuanceCosts

us-gaap_PaymentsOfDebtIssuanceCosts

bxp_TransferOfTenantImprovementsRealEstate

bxp_TransferOfTenantImprovementsRealEstate

12,331,000

bxp_TransferOfTenantImprovementsRealEstate

bxp_TransferOfTenantImprovementsRealEstate

bxp_TransferOfTenantImprovementsRealEstate

12,331,000

bxp_TransferOfTenantImprovementsRealEstate

bxp_ConstructionInProgressNetDeconsolidated

(299,947,000)

bxp_ConstructionInProgressNetDeconsolidated

bxp_ConstructionInProgressNetDeconsolidated

bxp_ConstructionInProgressNetDeconsolidated

(299,947,000)

bxp_ConstructionInProgressNetDeconsolidated

bxp_ConstructionInProgressNetDeconsolidated

us-gaap_ProceedsFromIssuanceOrSaleOfEquity

24,214,000

us-gaap_ProceedsFromIssuanceOrSaleOfEquity

3,277,000

us-gaap_ProceedsFromIssuanceOrSaleOfEquity

13,710,000

us-gaap_ProceedsFromIssuanceOrSaleOfEquity

24,214,000

us-gaap_ProceedsFromIssuanceOrSaleOfEquity

3,277,000

us-gaap_ProceedsFromIssuanceOrSaleOfEquity

13,710,000

us-gaap_PaymentsOfDividends

683,753,000

us-gaap_PaymentsOfDividends

688,904,000

us-gaap_PaymentsOfDividends

666,294,000

us-gaap_PaymentsOfDividends

683,753,000

us-gaap_PaymentsOfDividends

688,904,000

Prepaid expenses and other assets, net deconsolidated

us-gaap_PaymentsOfDividends

666,294,000

bxp_PrepaidExpensesAndOtherAssetsNetDeconsolidated

(5,011,000)

Prepaid expenses and other assets, net deconsolidated

bxp_PrepaidExpensesAndOtherAssetsNetDeconsolidated

Prepaid expenses and other assets, net deconsolidated

bxp_PrepaidExpensesAndOtherAssetsNetDeconsolidated

Prepaid expenses and other assets, net deconsolidated

bxp_PrepaidExpensesAndOtherAssetsNetDeconsolidated

(5,011,000)

Prepaid expenses and other assets, net deconsolidated

bxp_PrepaidExpensesAndOtherAssetsNetDeconsolidated

Prepaid expenses and other assets, net deconsolidated

bxp_PrepaidExpensesAndOtherAssetsNetDeconsolidated

us-gaap_LeaseCost

(62,850,000)

us-gaap_LeaseCost

(79,772,000)

us-gaap_LeaseCost

(117,282,000)

us-gaap_LeaseCost

(62,850,000)

us-gaap_LeaseCost

(79,772,000)

us-gaap_LeaseCost

(117,282,000)

us-gaap_AccretionExpense

(8,500,000)

us-gaap_AccretionExpense

us-gaap_AccretionExpense

(763,000)

us-gaap_AccretionExpense

(8,500,000)

us-gaap_AccretionExpense

Issuance of restricted securities to employees and directors

us-gaap_AccretionExpense

(763,000)

bxp_IssuanceOfRestrictedSecuritiesToEmployeesAndDirectors

44,405,000

Issuance of restricted securities to employees and directors

bxp_IssuanceOfRestrictedSecuritiesToEmployeesAndDirectors

42,607,000

Issuance of restricted securities to employees and directors

bxp_IssuanceOfRestrictedSecuritiesToEmployeesAndDirectors

37,622,000

us-gaap_PaymentsToMinorityShareholders

259,764,000

us-gaap_PaymentsToMinorityShareholders

58,811,000

us-gaap_PaymentsToMinorityShareholders

69,913,000

us-gaap_PaymentsToMinorityShareholders

259,764,000

us-gaap_PaymentsToMinorityShareholders

58,811,000

Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities

us-gaap_PaymentsToMinorityShareholders

69,913,000

us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities

501,295,000

Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities

us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities

138,149,000

Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities

us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities

529,166,000

Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities

us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities

491,456,000

Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities

us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities

118,101,000

Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities

us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivities

519,443,000

Proceeds from (Payments to) Noncontrolling Interests

us-gaap_ProceedsFromPaymentsToMinorityShareholders

Proceeds from (Payments to) Noncontrolling Interests

us-gaap_ProceedsFromPaymentsToMinorityShareholders

Proceeds from (Payments to) Noncontrolling Interests

us-gaap_ProceedsFromPaymentsToMinorityShareholders

(186,963,000)

Proceeds from (Payments to) Noncontrolling Interests

us-gaap_ProceedsFromPaymentsToMinorityShareholders

Proceeds from (Payments to) Noncontrolling Interests

us-gaap_ProceedsFromPaymentsToMinorityShareholders

Proceeds from (Payments to) Noncontrolling Interests

us-gaap_ProceedsFromPaymentsToMinorityShareholders

(186,963,000)

Net Cash Provided by (Used in) Operating Activities

us-gaap_NetCashProvidedByUsedInOperatingActivities

1,133,227,000

Net Cash Provided by (Used in) Operating Activities

us-gaap_NetCashProvidedByUsedInOperatingActivities

1,156,840,000

Net Cash Provided by (Used in) Operating Activities

us-gaap_NetCashProvidedByUsedInOperatingActivities

1,181,165,000

Net Cash Provided by (Used in) Operating Activities

us-gaap_NetCashProvidedByUsedInOperatingActivities

1,133,227,000

Net Cash Provided by (Used in) Operating Activities

us-gaap_NetCashProvidedByUsedInOperatingActivities

1,156,840,000

Net Cash Provided by (Used in) Operating Activities

us-gaap_NetCashProvidedByUsedInOperatingActivities

1,181,165,000

us-gaap_PaymentsToAcquireAndDevelopRealEstate

222,260,000

us-gaap_PaymentsToAcquireAndDevelopRealEstate

137,976,000

us-gaap_PaymentsToAcquireAndDevelopRealEstate

149,031,000

us-gaap_PaymentsToAcquireAndDevelopRealEstate

222,260,000

us-gaap_PaymentsToAcquireAndDevelopRealEstate

137,976,000

Net Cash Provided by (Used in) Financing Activities

us-gaap_PaymentsToAcquireAndDevelopRealEstate

149,031,000

us-gaap_NetCashProvidedByUsedInFinancingActivities

(1,311,442,000)

Net Cash Provided by (Used in) Financing Activities

us-gaap_NetCashProvidedByUsedInFinancingActivities

484,322,000

Net Cash Provided by (Used in) Financing Activities

us-gaap_NetCashProvidedByUsedInFinancingActivities

(113,379,000)

Net Cash Provided by (Used in) Financing Activities

us-gaap_NetCashProvidedByUsedInFinancingActivities

(1,311,442,000)

Net Cash Provided by (Used in) Financing Activities

us-gaap_NetCashProvidedByUsedInFinancingActivities

484,322,000

Net Cash Provided by (Used in) Financing Activities

us-gaap_NetCashProvidedByUsedInFinancingActivities

(113,379,000)

us-gaap_PaymentsToAcquireOtherProductiveAssets

513,878,000

us-gaap_PaymentsToAcquireOtherProductiveAssets

482,507,000

us-gaap_PaymentsToAcquireOtherProductiveAssets

546,060,000

us-gaap_PaymentsToAcquireOtherProductiveAssets

513,878,000

us-gaap_PaymentsToAcquireOtherProductiveAssets

482,507,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect

us-gaap_PaymentsToAcquireOtherProductiveAssets

546,060,000

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

(1,218,171,000)

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

1,027,443,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

52,695,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

(1,218,171,000)

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

1,027,443,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

52,695,000

us-gaap_PaymentsForCapitalImprovements

150,998,000

us-gaap_PaymentsForCapitalImprovements

160,126,000

us-gaap_PaymentsForCapitalImprovements

180,556,000

us-gaap_PaymentsForCapitalImprovements

150,998,000

us-gaap_PaymentsForCapitalImprovements

160,126,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

us-gaap_PaymentsForCapitalImprovements

180,556,000

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

1,719,329,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

691,886,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

639,191,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

501,158,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

1,719,329,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

691,886,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

639,191,000

Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents

us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

501,158,000

us-gaap_IncreaseDecreaseInAccountsReceivable

(4,820,000)

us-gaap_IncreaseDecreaseInAccountsReceivable

(22,550,000)

us-gaap_IncreaseDecreaseInAccountsReceivable

24,876,000

us-gaap_IncreaseDecreaseInAccountsReceivable

(4,820,000)

us-gaap_IncreaseDecreaseInAccountsReceivable

(22,550,000)

us-gaap_IncreaseDecreaseInAccountsReceivable

24,876,000

us-gaap_PaymentsForTenantImprovements

263,952,000

us-gaap_PaymentsForTenantImprovements

234,423,000

us-gaap_PaymentsForTenantImprovements

251,831,000

us-gaap_PaymentsForTenantImprovements

263,952,000

us-gaap_PaymentsForTenantImprovements

234,423,000

us-gaap_PaymentsForTenantImprovements

251,831,000

us-gaap_IncreaseDecreaseInFinanceReceivables

545,000

us-gaap_IncreaseDecreaseInFinanceReceivables

19,000

us-gaap_IncreaseDecreaseInFinanceReceivables

(4,000)

us-gaap_IncreaseDecreaseInFinanceReceivables

545,000

us-gaap_IncreaseDecreaseInFinanceReceivables

19,000

us-gaap_IncreaseDecreaseInFinanceReceivables

(4,000)

us-gaap_StraightLineRent

101,548,000

us-gaap_StraightLineRent

97,099,000

us-gaap_StraightLineRent

56,817,000

us-gaap_StraightLineRent

101,548,000

us-gaap_StraightLineRent

97,099,000

us-gaap_StraightLineRent

56,817,000

bxp_Rightofuseassetsfinanceleases

bxp_Rightofuseassetsfinanceleases

bxp_Rightofuseassetsfinanceleases

5,152,000

bxp_Rightofuseassetsfinanceleases

bxp_Rightofuseassetsfinanceleases

Increase (Decrease) in Prepaid Expense and Other Assets

bxp_Rightofuseassetsfinanceleases

5,152,000

us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

20,811,000

Increase (Decrease) in Prepaid Expense and Other Assets

us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

(12,488,000)

Increase (Decrease) in Prepaid Expense and Other Assets

us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

(2,965,000)

Increase (Decrease) in Prepaid Expense and Other Assets

us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

20,811,000

Increase (Decrease) in Prepaid Expense and Other Assets

us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

(12,488,000)

Increase (Decrease) in Prepaid Expense and Other Assets

us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets

(2,965,000)

Interest Paid, Including Capitalized Interest, Operating and Investing Activities

us-gaap_InterestPaid

465,442,000

Interest Paid, Including Capitalized Interest, Operating and Investing Activities

us-gaap_InterestPaid

433,492,000

Interest Paid, Including Capitalized Interest, Operating and Investing Activities

us-gaap_InterestPaid

439,059,000

Interest Paid, Including Capitalized Interest, Operating and Investing Activities

us-gaap_InterestPaid

465,442,000

Interest Paid, Including Capitalized Interest, Operating and Investing Activities

us-gaap_InterestPaid

433,492,000

Interest Paid, Including Capitalized Interest, Operating and Investing Activities

us-gaap_InterestPaid

439,059,000

us-gaap_InterestCostsCapitalized

53,097,000

us-gaap_InterestCostsCapitalized

53,881,000

us-gaap_InterestCostsCapitalized

54,911,000

us-gaap_InterestCostsCapitalized

53,097,000

us-gaap_InterestCostsCapitalized

53,881,000

us-gaap_InterestCostsCapitalized

54,911,000

us-gaap_FinanceLeaseInterestPaymentOnLiability

us-gaap_FinanceLeaseInterestPaymentOnLiability

568,000

us-gaap_FinanceLeaseInterestPaymentOnLiability

us-gaap_FinanceLeaseInterestPaymentOnLiability

us-gaap_FinanceLeaseInterestPaymentOnLiability

568,000

Increase (Decrease) in Accounts Payable and Accrued Liabilities

us-gaap_FinanceLeaseInterestPaymentOnLiability

us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

20,025,000

Increase (Decrease) in Accounts Payable and Accrued Liabilities

us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

(4,059,000)

Increase (Decrease) in Accounts Payable and Accrued Liabilities

us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

12,627,000

Increase (Decrease) in Accounts Payable and Accrued Liabilities

us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

20,025,000

Increase (Decrease) in Accounts Payable and Accrued Liabilities

us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

(4,059,000)

Increase (Decrease) in Accounts Payable and Accrued Liabilities

us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities

12,627,000

us-gaap_IncreaseDecreaseInInterestPayableNet

(10,839,000)

us-gaap_IncreaseDecreaseInInterestPayableNet

16,211,000

us-gaap_IncreaseDecreaseInInterestPayableNet

858,000

us-gaap_IncreaseDecreaseInInterestPayableNet

(10,839,000)

us-gaap_IncreaseDecreaseInInterestPayableNet

16,211,000

us-gaap_IncreaseDecreaseInInterestPayableNet

858,000

us-gaap_IncreaseDecreaseInOtherOperatingLiabilities

(28,739,000)

us-gaap_IncreaseDecreaseInOtherOperatingLiabilities

17,629,000

us-gaap_IncreaseDecreaseInOtherOperatingLiabilities

(49,569,000)

us-gaap_IncreaseDecreaseInOtherOperatingLiabilities

(28,739,000)

us-gaap_IncreaseDecreaseInOtherOperatingLiabilities

17,629,000

us-gaap_IncreaseDecreaseInOtherOperatingLiabilities

(49,569,000)

us-gaap_ProceedsFromLinesOfCredit

770,000,000

us-gaap_ProceedsFromLinesOfCredit

265,000,000

us-gaap_ProceedsFromLinesOfCredit

380,000,000

us-gaap_ProceedsFromLinesOfCredit

770,000,000

us-gaap_ProceedsFromLinesOfCredit

265,000,000

Salaries And Related Costs Capitalized

us-gaap_ProceedsFromLinesOfCredit

380,000,000

bxp_SalariesAndRelatedCostsCapitalized

13,700,000

Salaries And Related Costs Capitalized

bxp_SalariesAndRelatedCostsCapitalized

12,900,000

Salaries And Related Costs Capitalized

bxp_SalariesAndRelatedCostsCapitalized

10,400,000

Cash FDIC Insured Limit

bxp_CashFDICInsuredLimit

250,000

us-gaap_ShareBasedCompensation

50,860,000

us-gaap_ShareBasedCompensation

44,142,000

us-gaap_ShareBasedCompensation

40,958,000

us-gaap_ShareBasedCompensation

50,860,000

us-gaap_ShareBasedCompensation

44,142,000

Proceeds from Equity Method Investment, Distribution

us-gaap_ShareBasedCompensation

40,958,000

us-gaap_EquityMethodInvestmentDividendsOrDistributions

21,542,000

Proceeds from Equity Method Investment, Distribution

us-gaap_EquityMethodInvestmentDividendsOrDistributions

31,892,000

Proceeds from Equity Method Investment, Distribution

us-gaap_EquityMethodInvestmentDividendsOrDistributions

17,155,000

Proceeds from Equity Method Investment, Distribution

us-gaap_EquityMethodInvestmentDividendsOrDistributions

21,542,000

Proceeds from Equity Method Investment, Distribution

us-gaap_EquityMethodInvestmentDividendsOrDistributions

31,892,000

Proceeds from Equity Method Investment, Distribution

us-gaap_EquityMethodInvestmentDividendsOrDistributions

17,155,000

us-gaap_GainLossOnSaleOfInvestments

5,626,000

us-gaap_GainLossOnSaleOfInvestments

5,261,000

us-gaap_GainLossOnSaleOfInvestments

6,417,000

us-gaap_GainLossOnSaleOfInvestments

5,626,000

us-gaap_GainLossOnSaleOfInvestments

5,261,000

us-gaap_GainLossOnSaleOfInvestments

6,417,000

us-gaap_ProvisionForLoanAndLeaseLosses

(1,207,000)

us-gaap_ProvisionForLoanAndLeaseLosses

1,849,000

us-gaap_ProvisionForLoanAndLeaseLosses

us-gaap_ProvisionForLoanAndLeaseLosses

(1,207,000)

us-gaap_ProvisionForLoanAndLeaseLosses

1,849,000

us-gaap_ProvisionForLoanAndLeaseLosses

us-gaap_PaidInKindInterest

23,368,000

us-gaap_PaidInKindInterest

23,384,000

us-gaap_PaidInKindInterest

22,254,000

us-gaap_PaidInKindInterest

23,368,000

us-gaap_PaidInKindInterest

23,384,000