0001656423-23-000024 | 10-Q | XBRL Viewer

General and administrative

803,200

754,307

Expenses

Rental

291,308

270,255

55,802

43,194

911

208,734

177,624

568,661

499,978

Loss from Unconsolidated Joint Ventures

(7,569)

2,189

Gains on sales of real estate

22,701

Interest and other income (loss)

10,941

1,228

Gains (losses) from investments in securities

1,665

(2,262)

Unrealized gain on non-real estate investment

259

(134,207)

(101,228)

Net income attributable to noncontrolling interests

105,628

176,957

Noncontrolling interests in property partnerships

(18,660)

(17,549)

Noncontrolling interest - common units of the Operating Partnership

(9,078)

(16,361)

Net income attributable to the Company

77,890

143,047

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

$ 77,890

$ 143,047

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)

$ 0.50

$ 0.91

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

156,803

156,650

Diluted earnings per common share / unit attributable to the Company

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

$ 0.50

$ 0.91

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

157,043

157,004

Revenue

Lease

$ 756,875

$ 718,120

General and administrative

803,200

754,307

Expenses

Rental

291,308

270,255

55,802

43,194

911

206,872

175,886

566,799

498,240

Loss from Unconsolidated Joint Ventures

(7,569)

2,189

Gains on sales of real estate

23,384

Interest and other income (loss)

10,941

1,228

Gains (losses) from investments in securities

1,665

(2,262)

Unrealized gain on non-real estate investment

259

(134,207)

(101,228)

Net income attributable to noncontrolling interests

107,490

179,378

Noncontrolling interests in property partnerships

(18,660)

(17,549)

Net income attributable to the Company

88,830

161,829

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

$ 88,830

$ 161,829

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)

$ 0.51

$ 0.93

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

174,652

174,276

Diluted earnings per common share / unit attributable to the Company

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

$ 0.51

$ 0.93

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

174,892

174,630

Parking and Other [Member]

Revenue

Parking and Other [Member] | Boston Properties Limited Partnership

$ 24,009

$ 21,734

Revenue

24,009

21,734

Hotel [Member]

Revenue

^[1]

8,101

4,557

Expenses

Hotel [Member] | Boston Properties Limited Partnership

6,671

4,840

Revenue

8,101

4,557

Expenses

Real Estate, Other [Member]

6,671

4,840

Revenue

5,235

4,065

Expenses

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

5,235

4,065

Revenue

5,235

4,065

Expenses

Management Service [Member]

5,235

4,065

Revenue

Management Service [Member] | Boston Properties Limited Partnership

8,980

5,831

Revenue

Dividends Declared [Table Text Block]

$ 8,980

$ 5,831

[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.

Stock Option and Incentive Plan (Narrative) (Details) - USD ($) $ in Thousands	Feb. 07, 2023	Feb. 03, 2023
MYLTIP 2020 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards		$ 3,800
Final awards percentage of target		50.00%
Forfeitures, in units		152,460
MYLTIP 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award	The 2023 MYLTIP awards consist of two, equally weighted (50% each) components that utilize BXP’s TSR over a three-year measurement period as the performance metric.
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 6, 2026, but, in general, may not be converted, redeemed, sold or otherwise transferred for one additional year thereafter.
Value of MYLTIP Awards	$ 13,100
Minimum [Member] \| MYLTIP 2023 \| Boston Properties Limited Partnership
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance	0
Maximum [Member] \| MYLTIP 2023 \| Boston Properties Limited Partnership
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance	322,053
Target \| MYLTIP 2023 \| Boston Properties Limited Partnership
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance	161,026

Stockholders' Equity / Partners' Capital (Tables)

3 Months Ended

Mar. 31, 2023

Class of Stock [Line Items]

The following table presents BXP’s dividends per share and BPLP’s distributions per OP Unit and LTIP Unit paid or declared in 2023 and during the three months ended March 31, 2022:


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
March 31, 2023	April 28, 2023	$0.98	$0.98
December 30, 2022	January 30, 2023	$0.98	$0.98



March 31, 2022	April 29, 2022	$0.98	$0.98
December 31, 2021	January 28, 2022	$0.98	$0.98

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

3 Months Ended

Mar. 31, 2023

Mar. 31, 2022

^[1]

$ 769,158

$ 726,888

^[1]

11,726

12,966

^[1]

$ 788,985

$ 744,411

100.00%

$ 285,845

$ 263,823

5,463

6,432

$ 297,979

$ 275,095

100.00%

$ 491,006

$ 469,316

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

100.00%

100.00%

Boston [Member]

^[1]

$ 269,951

$ 242,078

^[1]

4,049

3,596

^[1]

$ 282,101

$ 250,231

35.76%

33.61%

$ 100,049

$ 90,528

1,552

1,437

$ 108,272

$ 96,805

36.34%

35.19%

$ 173,829

$ 153,426

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

35.41%

32.69%

35.41%

32.94%

Los Angeles [Member]

^[1]

$ 0

^[1]

^[1]

$ 0

0.00%

$ 0

$ 0

0.00%

$ 0

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

0.00%

2.73%

2.99%

New York [Member]

^[1]

$ 258,192

$ 256,870

^[1]

^[1]

$ 258,192

$ 256,870

32.72%

34.51%

$ 102,485

$ 96,340

$ 102,485

$ 96,340

34.39%

35.02%

$ 155,707

$ 160,530

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

31.71%

34.21%

25.39%

27.21%

San Francisco [Member]

^[1]

$ 136,093

$ 132,375

^[1]

3,642

2,391

^[1]

$ 139,735

$ 134,766

17.71%

18.10%

$ 46,085

$ 43,408

2,173

1,868

$ 48,258

$ 45,276

16.20%

16.46%

$ 91,477

$ 89,490

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

18.63%

19.07%

19.59%

20.16%

Seattle

$ 14,258

^[1]

$ 0

^[1]

$ 14,258

^[1]

$ 0

1.81%

0.00%

$ 2,960

$ 0

$ 2,960

$ 0

0.99%

0.00%

$ 11,298

$ 0

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

2.30%

0.00%

2.71%

0.43%

Washington, DC [Member]

^[1]

$ 90,664

$ 95,565

^[1]

4,035

6,979

^[1]

$ 94,699

$ 102,544

12.00%

13.78%

$ 34,266

$ 33,547

1,738

3,127

$ 36,004

$ 36,674

12.08%

13.33%

$ 58,695

$ 65,870

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

11.95%

14.03%

14.17%

16.27%

Hotel [Member]

^[1]

$ 8,101

$ 4,557

Hotel [Member] | Boston [Member]

6,671

4,840

^[1]

8,101

4,557

Hotel [Member] | Los Angeles [Member]

6,671

4,840

^[1]

Hotel [Member] | New York [Member]

^[1]

Hotel [Member] | San Francisco [Member]

^[1]

Hotel [Member] | Seattle

^[1]

Hotel [Member] | Washington, DC [Member]

^[1]

Noncontrolling interest - property partnerships [Member]

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

(47,097)

(47,055)

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

(10,817)

(11,735)

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

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

(36,280)

(35,320)

Noncontrolling interest - property partnerships [Member] | Seattle

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

Unconsolidated Joint Ventures [Member] | Boston [Member]

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

8,577

9,693

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

13,225

13,757

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

3,650

(156)

Unconsolidated Joint Ventures [Member] | Seattle

3,464

3,181

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

1,846

1,955

9,994

8,891

Company's Share [Member]

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

484,665

459,582

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

171,589

151,384

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

13,225

13,757

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

123,077

125,054

Company's Share [Member] | Seattle

94,941

92,671

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

13,144

1,955

$ 68,689

$ 74,761

[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.

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

Mar. 31, 2023

Dec. 31, 2022

ASSETS

$ 19,539,375

$ 19,496,442

Total assets

24,625,422

24,207,669

Mortgage and notes payable, net

3,273,553

3,272,368

Members’/Partners’ equity

465,276

450,918

6,062,787

6,132,919

Total liabilities and equity / capital

24,625,422

24,207,669

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

1,752,617

1,715,911

237,503

237,510

Lease liabilities - finance leases

166,699

167,351

250,567

249,335

Lease liabilities - operating leases

204,435

204,686

ASSETS

^[1]

6,649,580

6,537,554

Other assets

755,055

756,786

Total assets

7,404,635

7,294,340

Mortgage and notes payable, net

4,037,789

4,022,746

Members’/Partners’ equity

^[2]

723,660

716,271

2,643,186

2,555,323

Total liabilities and equity / capital

7,404,635

7,294,340

Company's share of equity

1,271,419

1,238,929

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

^[3]

399,705

391,556

^[4]

1,671,124

1,630,485

248,900

Lease liabilities - finance leases

20,900

21,200

381,000

382,200

Lease liabilities - operating leases

30,500

81,500

85,400

Colorado Center

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

301,097

301,820

^[5]

234,635

233,862

Gateway Commons Complex [Member]

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

47,707

47,808

^[5]

337,535

324,038

Dock 72

^[5]

(15,362)

(19,921)

(98,120)

(98,980)

200 Fifth Avenue JV LLC

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

99,381

94,497

^[5]

$ 114,919

$ 120,083

[1]

At March 31, 2023 and December 31, 2022, this amount included right of use assets - finance leases totaling approximately $248.9 million. At March 31, 2023 and December 31, 2022, this amount included right of use assets - operating leases totaling approximately $20.9 million and $21.2 million, respectively.

[2]

At March 31, 2023 and December 31, 2022, this amount included lease liabilities - finance leases totaling approximately $381.0 million and $382.2 million, respectively. At March 31, 2023 and December 31, 2022, this amount included lease liabilities - operating leases totaling approximately $30.5 million.

[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:


	March 31, 2023		December 31, 2022
Property	(in thousands)
Colorado Center	$	301,097	$	301,820
200 Fifth Avenue	99,381		94,497
Gateway Commons	47,707		47,808
Dock 72	(98,120)		(98,980)

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 $81.5 million and $85.4 million at March 31, 2023 and December 31, 2022, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

[5]

Investments with deficit balances aggregating approximately $81.5 million and $85.4 million at March 31, 2023 and December 31, 2022, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.

Commitments And Contingencies	3 Months Ended
Commitments And Contingencies	Mar. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	7. 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 $25.7 million at March 31, 2023. 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 or joint venture partners whereby the partners agree to reimburse the joint venture for their share of any payments made under the guarantee. In some cases, the Company earns a fee from the applicable joint venture for providing the guarantee. In connection with the refinancing of 767 Fifth Avenue’s (the General Motors Building) secured loan by the Company’s consolidated joint venture entity, 767 Venture, LLC, the Company guaranteed the consolidated entity’s obligation to fund various reserves for tenant improvement costs and allowances, leasing commissions and free rent obligations in lieu of cash deposits. As of March 31, 2023, the maximum funding obligation under the guarantee was approximately $12.5 million. The Company earns a fee from the joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee. As of March 31, 2023, no amounts related to the guarantee were recorded as liabilities in the Company’s consolidated financial statements. In connection with the development of the Company’s 290 Binney Street project located in Cambridge, Massachusetts, which commenced on January 5, 2023 (see Note 3), the Cambridge Zoning Ordinance requires that a building permit for the construction of a residential project of at least 400,000 square feet be issued prior to or concurrently with the issuance of a building permit for the commercial building. 290 Binney Street and the residential project are components of the Company’s future life sciences development project located in the heart of Kendall Square in Cambridge, Massachusetts, proposed to ultimately consist of two premier workplace properties aggregating approximately 1.1 million rentable square feet of life sciences space and the approximately 400,000 square foot residential building. The commencement of construction of each phase of the overall project is subject to various conditions, some of which are not within the Company’s control. There can be no assurance that the conditions will be satisfied or that the Company will commence the development of the remaining phases on the terms and schedule currently contemplated or at all. 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 $330 million per occurrence limit, and a $330 million annual aggregate limit, $30 million of which is provided by IXP, as a direct insurer. This insurance is subject to a deductible in the amount of 5% of the value of the affected property. In addition, the Company currently carries earthquake insurance which covers its Seattle region with a $110 million per occurrence limit, and a $110 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, BPLP has issued a guarantee to cover liabilities of IXP in the amount of $20.0 million. The Company continues to monitor the state of the insurance market in general, and the scope and costs of coverage for acts of terrorism, 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.

Summary Of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2023

Summary Of Significant Accounting Policies [Line Items]

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

The Company follows the authoritative guidance for fair value measurements when valuing its financial instruments for disclosure purposes. The table below presents for March 31, 2023 and December 31, 2022, the financial instruments that are being valued for disclosure purposes as well as the Level at which they are categorized (as defined in Accounting Standards Codification (“ASC”) 820 “Fair Value Measurements and Disclosures”).


Financial Instrument			Level
Unsecured senior notes (1)			Level 1
Related party note receivable			Level 3
Sales-type lease receivable			Level 3
Mortgage notes payable			Level 3
Unsecured line of credit			Level 3
Unsecured term loan			Level 3

_______________

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

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.

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

The following table presents the aggregate carrying value of the Company’s related party note receivable, net, sales-type lease receivable, net, mortgage notes payable, net, unsecured senior notes, net, unsecured line of credit and unsecured term loan, net and the Company’s corresponding estimate of fair value as of March 31, 2023 and December 31, 2022 (in thousands):


	March 31, 2023				December 31, 2022
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable, net	$	78,544	$	79,472	$	78,576	$	79,220
Sales-type lease receivable, net	13,028		13,086		12,811		13,045
Total	$	91,572	$	92,558	$	91,387	$	92,265

Mortgage notes payable, net	$	3,273,553	$	2,826,826	$	3,272,368	$	2,744,479
Unsecured senior notes, net	10,240,967		8,759,487		10,237,968		9,135,512
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	1,194,916		1,200,000		730,000		730,000
Total	$	14,709,436	$	12,786,313	$	14,240,336	$	12,609,991

Summary Of Significant Accounting Policies (Policies)	3 Months Ended
Summary Of Significant Accounting Policies (Policies)	Mar. 31, 2023
Accounting Policies [Abstract]
Use of Estimates in the Preparation of Financial Statements	The Company bases its estimates on historical experience and on various other assumptions that it considers to be reasonable under the circumstances, including the impact of extraordinary events such as the coronavirus (“COVID-19”) pandemic, the results of which form the basis for making significant judgments about the carrying values of assets and liabilities, assessments of future collectability, and other areas of the financial statements that are impacted by the use of estimates. Actual results may differ from these estimates under different assumptions or conditions.

Investment in Unconsolidated Joint Ventures (Narrative) (Details) - Worldgate Drive - Unconsolidated Properties $ in Thousands	Jan. 31, 2023 USD ($) ft² a Building Vehicles
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%
Payments to Acquire Interest in Joint Venture \| $	$ 17,000
Net Rentable Area (in sf) \| ft²	350,000
Number of buildings \| Building	2
Number of parking space \| Vehicles	1,200
Area of Land \| a	10

Subsequent Events (Details) $ in Thousands	Jun. 01, 2023	May 02, 2023 USD ($)	Apr. 21, 2023 USD ($) ft² Year	Jan. 04, 2023 Rate	Apr. 29, 2023 ft²
2023 Unsecured Term Loan
Subsequent Event [Line Items]
Debt Instrument, Basis Spread on Variable Rate \| Rate				1.00%
Interest Rate Swap
Subsequent Event [Line Items]
Derivative, Inception Date		May 02, 2023
Derivative, Notional Amount \| $		$ 1,200,000
Derivative, Average Fixed Interest Rate		4.642%
Derivative, Maturity Date		May 16, 2024
Subsequent Event [Member] \| 2023 Unsecured Term Loan
Subsequent Event [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		5.592%
Subsequent Event [Member] \| 2100 Pennsylvania Avenue
Subsequent Event [Line Items]
Area of Real Estate Property \| ft²					480,000
Subsequent Event [Member] \| Unconsolidated Joint Ventures [Member] \| 7750 Wisconsin Avenue [Member]
Subsequent Event [Line Items]
Ownership Percentage			50.00%
Area of Real Estate Property \| ft²			734,000
Leased percentage			100.00%
Debt Instrument, Description of Variable Rate Basis	Term SOFR
Debt Instrument, Basis Spread on Variable Rate	1.35%
Extension Option (in years) \| Year			1
Subsequent Event [Member] \| Unconsolidated Joint Ventures [Member] \| 7750 Wisconsin Avenue [Member] \| Extended Maturity
Subsequent Event [Line Items]
Debt Instrument, Term			1 year
Construction Loan \| $			$ 252,600

Stockholders' Equity / Partners' Capital

3 Months Ended

Mar. 31, 2023

Equity [Abstract]

Stockholders' Equity / Partners' Capital

9. Stockholders’ Equity / Partners’ Capital

As of March 31, 2023, BXP had 156,829,793 shares of Common Stock outstanding.

As of March 31, 2023, BXP owned 1,754,892 general partnership units and 155,074,901 limited partnership units in BPLP.

On May 22, 2020, BXP 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, BXP 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 BXP’s prior $600.0 million ATM stock offering program that was scheduled to expire on June 2, 2020. BXP intends to use the net proceeds from any offering for general business purposes, which may include investment opportunities and debt reduction. No shares of Common Stock have been issued under this ATM stock offering program.

During the three months ended March 31, 2023, BXP did not issue any shares of Common Stock upon the exercise of options to purchase Common Stock. As a result of the exercise period ending on February 1, 2023, 49,359 options were forfeited.

During the three months ended March 31, 2023, BXP issued 5,188 shares of Common Stock in connection with the redemption of an equal number of redeemable OP Units from limited partners.

The following table presents BXP’s dividends per share and BPLP’s distributions per OP Unit and LTIP Unit paid or declared in 2023 and during the three months ended March 31, 2022:


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
March 31, 2023	April 28, 2023	$0.98	$0.98
December 30, 2022	January 30, 2023	$0.98	$0.98



March 31, 2022	April 29, 2022	$0.98	$0.98
December 31, 2021	January 28, 2022	$0.98	$0.98

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-URI https://asc.fasb.org/topic&trid=2208762

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496171-112644

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496171-112644

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI https://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496189-112644

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (g)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496189-112644

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (h)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 14
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496171-112644

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 18
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496189-112644

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 16
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496180-112644

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (i)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126731327&loc=SL126733271-114008

+ Details

Noncontrolling Interests

3 Months Ended

Mar. 31, 2023

Noncontrolling Interest [Abstract]

Noncontrolling Interest Disclosure [Text Block]

8. Noncontrolling Interests

Noncontrolling interests relate to the interests in BPLP not owned by BXP and interests in consolidated property partnerships not wholly-owned by the Company. As of March 31, 2023, the noncontrolling interests in BPLP consisted of 16,527,638 OP Units, 2,131,785 LTIP Units (including 514,854 LTIP Units earned by employees under the Company’s multi-year long-term incentive awards granted between 2012 and 2020 (i.e., 2012 OPP and 2013 - 2020 MYLTIP awards)), 350,989 2021 MYLTIP Units, 253,453 2022 MYLTIP Units and 322,053 2023 MYLTIP Units held by parties other than BXP.

Noncontrolling Interest—Common Units

During the three months ended March 31, 2023, 5,188 OP Units were presented by the holders for redemption (including an aggregate of 5,188 OP Units issued upon conversion of LTIP Units, 2012 OPP Units and MYLTIP Units) and were redeemed by BXP in exchange for an equal number of shares of Common Stock.

At March 31, 2023, BPLP had outstanding 350,989 2021 MYLTIP Units, 253,453 2022 MYLTIP Units and 322,053 2023 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 three-year performance period for each plan has ended, (1) 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 and (2) with respect to the 2021 - 2023 MYLTIP, the Company will make a “catch-up” cash payment on the MYLTIP Units that are ultimately earned in an amount equal to the regular and special dividends, if any, declared during the performance period on Common Stock, less the distributions actually paid during the performance period on all of the awarded 2021 - 2023 MYLTIP Units.

On February 3, 2023, the measurement period for the Company’s 2020 MYLTIP awards ended and, based on BXP’s relative TSR performance, the final payout was determined to be 50% of target, or an aggregate of approximately $3.8 million (after giving effect to employee separations). As a result, an aggregate of 152,460 2020 MYLTIP Units that had been previously granted were automatically forfeited.

Record Date

Payment Date

Distributions per OP Unit and LTIP Unit

Distributions per MYLTIP Unit

March 31, 2023

April 28, 2023

$0.98

$0.098

December 30, 2022

January 30, 2023

$0.98

$0.098

Record Date

Payment Date

Distributions per OP Unit and LTIP Unit

Distributions per MYLTIP Unit

March 31, 2022

April 29, 2022

$0.98

$0.098

December 31, 2021

January 28, 2022

$0.98

$0.098

A holder of an OP Unit may present the OP Unit to BPLP 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, BPLP must redeem the OP Unit for cash equal to the then value of a share of Common Stock of BXP. BXP 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 (other than OP Units owned by BXP), and LTIP Units (including the 2012 OPP Units and 2013 - 2020 MYLTIP Units), assuming in each case that all conditions had been met for the conversion thereof, had all of such units been redeemed at March 31, 2023 was approximately $1.1 billion based on the last reported price of a share of Common Stock on the New York Stock Exchange of $54.12 per share on March 31, 2023.

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 $1.5 billion at March 31, 2023 and December 31, 2022, respectively, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.

Consolidated Statement of Capital and Noncontrolling Interests - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
Common Stock, Shares, Outstanding	156,829,793		156,757,867
Net activity from stock option and incentive plan, value	$ 27,419	$ 18,921
Effective portion of interest rate contracts	(6,538)	7,565
Amortization of interest rate contracts	1,675	1,676
Contributions from noncontrolling interests in property partnerships	7,555	849
Distributions to noncontrolling interests in property partnerships	$ (21,606)	$ (26,640)
General Partner [Member]
Common Stock, Shares, Outstanding	1,755,000	1,749,000	1,750,000	1,746,000
Net activity from contributions and unearned compensation	5,000
Conversion of redeemable partnership units		3,000
Limited Partner [Member]
Common Stock, Shares, Outstanding	155,075,000	154,962,000	155,008,000	154,799,000
Net activity from contributions and unearned compensation	62,000	25,000
Conversion of redeemable partnership units	5,000	138,000
Partners' Capital (General and Limited Partners)[Member]
Beginning Balance	$ 5,449,936	$ 3,914,832	$ 5,299,428	$ 4,173,290
Net activity from contributions and unearned compensation, value	4,032	467
Allocated net income for the period	79,752	145,468
Distributions	(153,693)	(153,577)
Conversion of redeemable partnership units, value	195	5,028
Adjustment to reflect redeemable partnership units at redemption value	220,222	(255,844)
Accumulated Other Comprehensive Loss [Member]
Beginning Balance	(18,214)	(28,485)	(13,718)	(36,662)
Effective portion of interest rate contracts	(5,870)	6,800
Amortization of interest rate contracts	1,374	1,377
Noncontrolling interest - property partnerships [Member]
Beginning Balance	1,552,070	1,548,455	1,547,317	1,556,553
Allocated net income for the period	18,660	17,549
Amortization of interest rate contracts	144	144
Contributions from noncontrolling interests in property partnerships	7,555	849
Distributions to noncontrolling interests in property partnerships	(21,606)	(26,640)
Total Capital [Member]
Beginning Balance	6,983,792	5,434,802	6,833,027	5,693,181
Net activity from contributions and unearned compensation, value	4,032	467
Allocated net income for the period	98,412	163,017
Distributions	(153,693)	(153,577)
Conversion of redeemable partnership units, value	195	5,028
Adjustment to reflect redeemable partnership units at redemption value	220,222	(255,844)
Effective portion of interest rate contracts	(5,870)	6,800
Amortization of interest rate contracts	1,518	1,521
Contributions from noncontrolling interests in property partnerships	7,555	849
Distributions to noncontrolling interests in property partnerships	(21,606)	(26,640)
Noncontrolling interest - Redeemable partnership units [Member]
Beginning Balance	1,074,648	2,347,834	$ 1,280,886	$ 2,078,603
Net activity from contributions and unearned compensation, value	23,973	19,054
Allocated net income for the period	9,078	16,361
Distributions	(18,361)	(17,920)
Conversion of redeemable partnership units, value	(195)	(5,028)
Adjustment to reflect redeemable partnership units at redemption value	(220,222)	255,844
Effective portion of interest rate contracts	(668)	765
Amortization of interest rate contracts	$ 157	$ 155

Segment Information (Tables)

3 Months Ended

Mar. 31, 2023

Segment Reporting [Abstract]

Schedule Of Reconciliation Of Net Operating Income To Net Income

BXP


	Three months ended March 31,
	2023		2022
	(in thousands)
Net income attributable to Boston Properties, Inc.	$	77,890	$	143,047
Add:


Noncontrolling interest—common units of the Operating Partnership	9,078		16,361
Noncontrolling interests in property partnerships	18,660		17,549
Interest expense	134,207		101,228


Net operating income from unconsolidated joint ventures	40,756		37,321

Depreciation and amortization expense	208,734		177,624
Transaction costs	911		—
Payroll and related costs from management services contracts	5,235		4,065
General and administrative expense	55,802		43,194
Less:
Net operating income attributable to noncontrolling interests in property partnerships	47,097		47,055
Unrealized gain on non-real estate investment	259		—
Gains (losses) from investments in securities	1,665		(2,262)

Interest and other income (loss)	10,941		1,228

Gains on sales of real estate	—		22,701
Income (loss) from unconsolidated joint ventures	(7,569)		2,189
Direct reimbursements of payroll and related costs from management services contracts	5,235		4,065
Development and management services revenue	8,980		5,831
Company’s share of Net Operating Income	$	484,665	$	459,582

BPLP


	Three months ended March 31,
	2023		2022
	(in thousands)
Net income attributable to Boston Properties Limited Partnership	$	88,830	$	161,829
Add:


Noncontrolling interests in property partnerships	18,660		17,549
Interest expense	134,207		101,228


Net operating income from unconsolidated joint ventures	40,756		37,321

Depreciation and amortization expense	206,872		175,886
Transaction costs	911		—
Payroll and related costs from management services contracts	5,235		4,065
General and administrative expense	55,802		43,194
Less:
Net operating income attributable to noncontrolling interests in property partnerships	47,097		47,055
Unrealized gain on non-real estate investment	259		—
Gains (losses) from investments in securities	1,665		(2,262)

Interest and other income (loss)	10,941		1,228

Gains on sales of real estate	—		23,384
Income (loss) from unconsolidated joint ventures	(7,569)		2,189
Direct reimbursements of payroll and related costs from management services contracts	5,235		4,065
Development and management services revenue	8,980		5,831
Company’s share of Net Operating Income	$	484,665	$	459,582

Schedule Of Segment Information By Geographic Area And Property Type

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

For the three months ended March 31, 2023:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	269,951		$	—		$	258,192		$	136,093		$	14,258		$	90,664		$	769,158
Residential	4,049			—			—			3,642			—			4,035			11,726
Hotel	8,101			—			—			—			—			—			8,101
Total	282,101			—			258,192			139,735			14,258			94,699			788,985
% of Grand Totals	35.76		%	—		%	32.72		%	17.71		%	1.81		%	12.00		%	100.00		%
Rental Expenses:
Premier Workplace	100,049			—			102,485			46,085			2,960			34,266			285,845
Residential	1,552			—			—			2,173			—			1,738			5,463
Hotel	6,671			—			—			—			—			—			6,671
Total	108,272			—			102,485			48,258			2,960			36,004			297,979
% of Grand Totals	36.34		%	—		%	34.39		%	16.20		%	0.99		%	12.08		%	100.00		%
Net operating income	$	173,829		$	—		$	155,707		$	91,477		$	11,298		$	58,695		$	491,006
% of Grand Totals	35.41		%	—		%	31.71		%	18.63		%	2.30		%	11.95		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(10,817)			—			(36,280)			—			—			—			(47,097)
Add: Company’s share of net operating income from unconsolidated joint ventures	8,577			13,225			3,650			3,464			1,846			9,994			40,756
Company’s share of net operating income	$	171,589		$	13,225		$	123,077		$	94,941		$	13,144		$	68,689		$	484,665
% of Grand Totals	35.41		%	2.73		%	25.39		%	19.59		%	2.71		%	14.17		%	100.00		%

_______________

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

For the three months ended March 31, 2022:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	242,078		$	—		$	256,870		$	132,375		$	—		$	95,565		$	726,888
Residential	3,596			—			—			2,391			—			6,979			12,966
Hotel	4,557			—			—			—			—			—			4,557
Total	250,231			—			256,870			134,766			—			102,544			744,411
% of Grand Totals	33.61		%	—		%	34.51		%	18.10		%	—		%	13.78		%	100.00		%
Rental Expenses:
Premier Workplace	90,528			—			96,340			43,408			—			33,547			263,823
Residential	1,437			—			—			1,868			—			3,127			6,432
Hotel	4,840			—			—			—			—			—			4,840
Total	96,805			—			96,340			45,276			—			36,674			275,095
% of Grand Totals	35.19		%	—		%	35.02		%	16.46		%	—		%	13.33		%	100.00		%
Net operating income	$	153,426		$	—		$	160,530		$	89,490		$	—		$	65,870		$	469,316
% of Grand Totals	32.69		%	—		%	34.21		%	19.07		%	—		%	14.03		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(11,735)			—			(35,320)			—			—			—			(47,055)
Add: Company’s share of net operating income (loss) from unconsolidated joint ventures	9,693			13,757			(156)			3,181			1,955			8,891			37,321
Company’s share of net operating income	$	151,384		$	13,757		$	125,054		$	92,671		$	1,955		$	74,761		$	459,582
% of Grand Totals	32.94		%	2.99		%	27.21		%	20.16		%	0.43		%	16.27		%	100.00		%

_______________

Summary Of Significant Accounting Policies (Narrative) (Details)	Mar. 31, 2023
Summary Of Significant Accounting Policies [Line Items]
Number of VIEs	7
Variable Interest Entity, Primary Beneficiary [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of VIEs	6
Commercial Real Estate Properties [Member] \| Variable Interest Entity, Primary Beneficiary [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of VIEs	5

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

Mar. 31, 2023

Dec. 31, 2022

Land

$ 5,189,287

$ 5,189,811

237,503

237,510

Land held for future development

166,699

167,351

^[1]

626,137

721,501

Buildings and improvements

15,783,962

15,820,724

Tenant improvements

3,291,322

3,200,743

Furniture, Fixtures and Equipment

50,242

50,310

Construction in progress

618,770

406,574

Total

25,963,922

25,794,524

Less: accumulated depreciation

(6,424,547)

(6,298,082)

19,539,375

19,496,442

Land

5,094,578

5,095,102

237,503

237,510

Land held for future development

166,699

167,351

^[1]

626,137

721,501

Buildings and improvements

15,512,406

15,547,919

Tenant improvements

3,291,322

3,200,743

Furniture, Fixtures and Equipment

50,242

50,310

Construction in progress

618,770

406,574

Total

25,597,657

25,427,010

Less: accumulated depreciation

(6,306,326)

(6,180,474)

Summary Of Significant Accounting Policies

$ 19,291,331

$ 19,246,536

[1]	Includes pre-development costs.

Summary Of Significant Accounting Policies

3 Months Ended

Mar. 31, 2023

Accounting Policies [Abstract]

2. Summary of Significant Accounting Policies

BXP does not have any other significant assets, liabilities or operations, other than its investment in BPLP, nor does it have employees of its own. BPLP, not BXP, generally executes all significant business relationships other than transactions involving securities of BXP. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant

intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income.

The accompanying interim financial statements are unaudited; however, the financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission (the “SEC”). Accordingly, they do not include all of the disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting solely of normal recurring matters) necessary for a fair statement of the financial statements for these interim periods have been included. The results of operations for the interim periods are not necessarily indicative of the results to be obtained for other interim periods or for the full fiscal year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosure required by GAAP. These financial statements should be read in conjunction with the Company’s financial statements and notes thereto contained in the Company’s Annual Report in the Company’s Form 10-K for its fiscal year ended December 31, 2022.

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

Variable Interest Entities (VIEs)

Consolidated VIEs are those for which the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE. The assets of each VIE are only available to satisfy such VIE's respective liabilities. The Company has determined that it is the primary beneficiary for six of the seven entities that are VIEs as of March 31, 2023.

Consolidated Variable Interest Entities

As of March 31, 2023, BXP has identified six consolidated VIEs, including BPLP. Excluding BPLP, 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 BPLP’s interest) are reflected as noncontrolling interests in property partnerships in the accompanying consolidated financial statements (See Note 8).

In addition, BXP’s only significant asset is its investment in BPLP and, consequently, substantially all of BXP’s assets and liabilities are the assets and liabilities of BPLP.

Variable Interest Entities Not Consolidated

As of March 31, 2023, the Company has determined that the Platform 16 Holdings LP joint venture is a VIE. The Company does not consolidate this entity as the Company does not have the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and, therefore, the Company is not considered to be the primary beneficiary.

Fair Value of Financial Instruments


Financial Instrument			Level
Unsecured senior notes (1)			Level 1
Related party note receivable			Level 3
Sales-type lease receivable			Level 3
Mortgage notes payable			Level 3
Unsecured line of credit			Level 3
Unsecured term loan			Level 3

_______________

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


	March 31, 2023				December 31, 2022
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
Related party note receivable, net	$	78,544	$	79,472	$	78,576	$	79,220
Sales-type lease receivable, net	13,028		13,086		12,811		13,045
Total	$	91,572	$	92,558	$	91,387	$	92,265

Mortgage notes payable, net	$	3,273,553	$	2,826,826	$	3,272,368	$	2,744,479
Unsecured senior notes, net	10,240,967		8,759,487		10,237,968		9,135,512
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	1,194,916		1,200,000		730,000		730,000
Total	$	14,709,436	$	12,786,313	$	14,240,336	$	12,609,991

Stockholders' Equity / Partners' Capital Dividends / Distributions (Details) - $ / shares	Jan. 30, 2023	Apr. 29, 2022	Jan. 28, 2022	Mar. 20, 2023
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit				$ 0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	$ 0.98	$ 0.98	$ 0.98
Boston Properties Limited Partnership
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit				0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	0.98	0.98	0.98
Boston Properties Limited Partnership \| Op units and LTIP units
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit				0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	0.98	0.98	0.98
Boston Properties Limited Partnership \| Unvested MYLTIP Units [Member]
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit				$ 0.098
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	$ 0.098	$ 0.098	$ 0.098

Stock Option and Incentive Plan Stock and Units (Narrative) (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($) $ / shares shares	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued \| shares	156,908,693		156,836,767
Stock based compensation expense	$ 25,900	$ 20,900
Common Stock, Value, Issued	$ 1,568		$ 1,568
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued \| shares	66,634
LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value Of LTIP Units Issued	$ 28,100
Unvested Restricted stock and LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Annual Installments for Vesting	4
Boston Properties Limited Partnership \| LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
LTIP units issued (in shares) \| shares	403,446
Boston Properties Limited Partnership \| MYLTIP 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued \| shares	322,053
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share) \| $ / shares	$ 0.01
Common Stock, Value, Issued	$ 5,000
LTIP and MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share) \| $ / shares	$ 0.25
Ltips (including vested MYLTIPS) And Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses	$ 36,000
Unvested MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses	$ 9,100
Weighted-average period (years)	2 years 4 months 24 days

Noncontrolling Interests Common Units Distributions (Details) - $ / shares	Jan. 30, 2023	Apr. 29, 2022	Jan. 28, 2022	Mar. 20, 2023
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit				$ 0.98
Dividends, Per Unit, Cash Paid	$ 0.98	$ 0.98	$ 0.98
Boston Properties Limited Partnership
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit				0.98
Dividends, Per Unit, Cash Paid	0.98	0.98	0.98
Boston Properties Limited Partnership \| Op units and LTIP units
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit				0.98
Dividends, Per Unit, Cash Paid	0.98	0.98	0.98
Boston Properties Limited Partnership \| Unvested MYLTIP Units [Member]
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit				$ 0.098
Dividends, Per Unit, Cash Paid	$ 0.098	$ 0.098	$ 0.098

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

3 Months Ended

Mar. 31, 2023

Mar. 31, 2022

Effective portion of interest rate contracts

$ 105,628

$ 176,957

Other comprehensive income :

(6,538)

7,565

Amortization of interest rate contracts

^[1]

1,675

1,676

Other comprehensive income (loss)

(4,863)

9,241

Comprehensive Income

100,765

186,198

Net income attributable to noncontrolling interests

(27,738)

(33,910)

Other comprehensive (income) loss attributable to noncontrolling interests

368

(1,064)

Comprehensive income attributable to the Company

73,395

151,224

Effective portion of interest rate contracts

107,490

179,378

Other comprehensive income :

(6,538)

7,565

Amortization of interest rate contracts

^[2]

1,675

1,676

Other comprehensive income (loss)

(4,863)

9,241

Comprehensive Income

102,627

188,619

Net income attributable to noncontrolling interests

(18,804)

(17,693)

Comprehensive income attributable to the Company

$ 83,823

$ 170,926

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

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events On April 21, 2023, a joint venture in which BXP has a 50% interest exercised an option to extend by one year the maturity date of its $252.6 million construction loan collateralized by its 7750 Wisconsin Avenue property. The completed 734,000 square foot build-to-suit, premier workplace is located in Bethesda, Maryland and is 100% leased to an affiliate of Marriott International, Inc. Effective June 1, 2023, the financing will bear interest at a variable rate equal to Term SOFR plus 1.35% per annum and will now mature on April 26, 2024, with a one-year extension option, subject to certain conditions. On April 29, 2023, the Company completed and fully placed in-service 2100 Pennsylvania Avenue, a premier workplace project with approximately 480,000 net rentable square feet located in Washington, DC. On May 02, 2023, BPLP executed interest rate swaps in notional amounts aggregating $1.2 billion. These interest rate swaps were entered into to fix Term SOFR under for BPLP’s 2023 Unsecured Term Loan at a weighted-average rate of 4.6420% for the period commencing on May 4, 2023 and ending on May 16, 2024. Based on BPLP’s credit rating as of May 2, 2023, the interest rate for the 2023 Unsecured Term Loan would be 5.592% (See Note 6).

Investments in Unconsolidated Joint Ventures

3 Months Ended

Mar. 31, 2023

Investments In Unconsolidated Joint Ventures [Abstract]

Investments In Unconsolidated Joint Ventures

5. Investments in Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at March 31, 2023 and December 31, 2022:


					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			March 31, 2023		December 31, 2022
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.00	%		$	(6,097)	$	(6,198)
BP/CRF Metropolitan Square LLC	Metropolitan Square	20.00	%		(38,782)		(37,629)
901 New York, LLC	901 New York Avenue	25.00	%	(2)	(12,311)		(12,493)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.33	%	(3)	31,723		31,971
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.00	%		(8,941)		(9,185)
501 K Street LLC	1001 6th Street	50.00	%	(4)	43,661		42,922
Podium Developer LLC	The Hub on Causeway - Podium	50.00	%		45,622		46,839
Residential Tower Developer LLC	Hub50House	50.00	%		42,046		45,414
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.00	%		12,582		12,366
Office Tower Developer LLC	100 Causeway Street	50.00	%		59,811		59,716
1265 Main Office JV LLC	1265 Main Street	50.00	%		3,605		3,465
BNY Tower Holdings LLC	Dock 72	50.00	%	(5)	(15,362)		(19,921)

CA-Colorado Center, LLC	Colorado Center	50.00	%		234,635		233,862
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.00	%		51,549		52,152
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.00	%		115,966		116,397
SMBP Venture LP	Santa Monica Business Park	55.00	%		161,786		164,735
Platform 16 Holdings LP	Platform 16	55.00	%	(6)	171,010		158,109
Gateway Portfolio Holdings LLC	Gateway Commons	50.00	%		337,535		324,038
Rosecrans-Sepulveda Partners 4, LLC	Beach Cities Media Campus	50.00	%		26,987		27,000
Safeco Plaza REIT LLC	Safeco Plaza	33.67	%	(7)	68,196		69,785
360 PAS Holdco LLC	360 Park Avenue South	42.21	%	(8)	116,828		114,992
PR II/BXP Reston Gateway LLC	Reston Next Residential	20.00	%	(9)	11,431		11,351
751 Gateway Holdings LLC	751 Gateway	49.00	%		85,430		80,714
200 Fifth Avenue JV LLC	200 Fifth Avenue	26.69	%		114,919		120,083
ABXP Worldgate Investments LLC	13100 and 13150 Worldgate Drive	50.00	%		17,295		N/A
					$	1,671,124	$	1,630,485

_______________

(1)Investments with deficit balances aggregating approximately $81.5 million and $85.4 million at March 31, 2023 and December 31, 2022, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.

(2)The Company’s economic ownership has increased based on the achievement of certain return thresholds. At March 31, 2023 and December 31, 2022, 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)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 in excess of 520,000 square feet and achieving certain project returns at stabilization.

(5)This property includes net equity balances from the amenity joint venture.

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

(7)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 through which each partner owns its interest in the joint venture.

(8)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 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.

(9)The Company’s partner will fund required capital until its aggregate investment is approximately 80% of all capital contributions; thereafter, the partners will fund required capital according to their percentage interests.

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:


	March 31, 2023		December 31, 2022
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	6,649,580	$	6,537,554
Other assets	755,055		756,786
Total assets	$	7,404,635	$	7,294,340
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	4,037,789	$	4,022,746
Other liabilities (2)	723,660		716,271
Members’/Partners’ equity	2,643,186		2,555,323
Total liabilities and members’/partners’ equity	$	7,404,635	$	7,294,340
Company’s share of equity	$	1,271,419	$	1,238,929
Basis differentials (3)	399,705		391,556
Carrying value of the Company’s investments in unconsolidated joint ventures (4)	$	1,671,124	$	1,630,485

_______________

(1)At March 31, 2023 and December 31, 2022, this amount included right of use assets - finance leases totaling approximately $248.9 million. At March 31, 2023 and December 31, 2022, this amount included right of use assets - operating leases totaling approximately $20.9 million and $21.2 million, respectively.

(2)At March 31, 2023 and December 31, 2022, this amount included lease liabilities - finance leases totaling approximately $381.0 million and $382.2 million, respectively. At March 31, 2023 and December 31, 2022, this amount included lease liabilities - operating leases totaling approximately $30.5 million.

(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:


	March 31, 2023		December 31, 2022
Property	(in thousands)
Colorado Center	$	301,097	$	301,820
200 Fifth Avenue	99,381		94,497
Gateway Commons	47,707		47,808
Dock 72	(98,120)		(98,980)

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 $81.5 million and $85.4 million at March 31, 2023 and December 31, 2022, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

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


	Three months ended March 31,
	2023		2022
	(in thousands)
Total revenue (1)	$	151,423	$	124,491
Expenses
Operating	57,206		45,641
Transaction costs	74		—
Depreciation and amortization	49,978		44,664
Total expenses	107,258		90,305
Other income (expense)
Loss from early extinguishment of debt	—		(1,327)
Interest expense	(57,250)		(30,373)
Unrealized loss on derivative instruments	(10,610)		—

Net income (loss)	$	(23,695)	$	2,486

Company’s share of net income (loss)	$	(6,902)	$	3,394


Basis differential (2)	(667)		(1,205)
Income (loss) from unconsolidated joint ventures	$	(7,569)	$	2,189

_______________

(1)Includes straight-line rent adjustments of approximately $6.3 million and $27.5 million for the three months ended March 31, 2023 and 2022, respectively.

(2)Includes straight-line rent adjustments of approximately $0.3 million and $0.1 million for the three months ended March 31, 2023 and 2022, respectively. Also includes net above-/below-market rent adjustments of approximately $0.2 million and $0.1 million for the three months ended March 31, 2023 and 2022, respectively.

On January 31, 2023, the Company acquired a 50% interest in a joint venture that owns 13100 and 13150 Worldgate Drive located in Herndon, Virginia for a gross purchase price of approximately $17.0 million. The acquisition was completed with available cash. 13100 and 13150 Worldgate Drive consists of two vacant office buildings aggregating approximately 350,000 rentable square feet and a 1,200-space structured parking deck situated on a 10-acre site. The joint venture intends to redevelop the property for residential use. There can be no assurance that the joint venture will commence the development as currently contemplated or at all.

Real Estate (Tables)

3 Months Ended

Mar. 31, 2023

Schedule of Real Estate Properties

BXP

Real estate consisted of the following at March 31, 2023 and December 31, 2022 (in thousands):


	March 31, 2023		December 31, 2022
Land	$	5,189,287	$	5,189,811
Right of use assets - finance leases	237,503		237,510
Right of use assets - operating leases	166,699		167,351
Land held for future development (1)	626,137		721,501
Buildings and improvements	15,783,962		15,820,724
Tenant improvements	3,291,322		3,200,743
Furniture, fixtures and equipment	50,242		50,310
Construction in progress	618,770		406,574
Total	25,963,922		25,794,524
Less: Accumulated depreciation	(6,424,547)		(6,298,082)
	$	19,539,375	$	19,496,442

_______________

(1)Includes pre-development costs.

Schedule of Real Estate Properties

BPLP

Real estate consisted of the following at March 31, 2023 and December 31, 2022 (in thousands):


	March 31, 2023		December 31, 2022
Land	$	5,094,578	$	5,095,102
Right of use assets - finance leases	237,503		237,510
Right of use assets - operating leases	166,699		167,351
Land held for future development (1)	626,137		721,501
Buildings and improvements	15,512,406		15,547,919
Tenant improvements	3,291,322		3,200,743
Furniture, fixtures and equipment	50,242		50,310
Construction in progress	618,770		406,574
Total	25,597,657		25,427,010
Less: Accumulated depreciation	(6,306,326)		(6,180,474)
	$	19,291,331	$	19,246,536

_______________

(1)Includes pre-development costs.

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Noncontrolling Interest [Line Items]
Noncontrolling Interest in Limited Partnerships	$ 1,552,070	$ 1,547,317

Consolidated Statements Of Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Dividends In Excess Of Earnings [Member]	Treasury Stock, at cost [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]	Noncontrolling interest - property partnerships [Member]
Equity, shares at Dec. 31, 2021		156,545,000
Equity, value at Dec. 31, 2021	$ 8,033,228	$ 1,565	$ 6,497,730	$ (625,891)	$ (2,722)	$ (36,662)	$ 642,655	$ 1,556,553
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock, shares		141,000
Redemption of operating partnership units to common stock, value	0	$ 2	5,026				(5,028)
Allocated net income for the period	176,957			143,047			16,361	17,549
Dividends declared	(171,497)			(153,577)			(17,920)
Shares issued pursuant to stock purchase plan, shares		5,000
Shares issued pursuant to stock purchase plan, value	600		600
Net activity from stock option and incentive plan, shares		21,000
Net activity from stock option and incentive plan, value	18,921		(133)				19,054
Contributions from noncontrolling interests in property partnerships	849							849
Distributions to noncontrolling interests in property partnerships	(26,640)							(26,640)
Effective portion of interest rate contracts	7,565					6,800	765
Amortization of interest rate contracts	1,676					1,377	155	144
Reallocation of noncontrolling interest	0		6,440				(6,440)
Equity, shares at Mar. 31, 2022		156,712,000
Equity, value at Mar. 31, 2022	$ 8,041,659	$ 1,567	6,509,663	(636,421)	(2,722)	(28,485)	649,602	1,548,455
Equity, shares at Dec. 31, 2022	156,757,867	156,758,000
Equity, value at Dec. 31, 2022	$ 8,363,819	$ 1,568	6,539,147	(391,356)	(2,722)	(13,718)	683,583	1,547,317
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock, shares		5,000
Redemption of operating partnership units to common stock, value	0	$ 0	195				(195)
Allocated net income for the period	105,628			77,890			9,078	18,660
Dividends declared	(172,054)			(153,693)			(18,361)
Shares issued pursuant to stock purchase plan, shares		9,000
Shares issued pursuant to stock purchase plan, value	586		586
Net activity from stock option and incentive plan, shares		58,000
Net activity from stock option and incentive plan, value	27,419		3,448				23,971
Contributions from noncontrolling interests in property partnerships	7,555							7,555
Distributions to noncontrolling interests in property partnerships	(21,606)							(21,606)
Effective portion of interest rate contracts	(6,538)					(5,870)	(668)
Amortization of interest rate contracts	1,675					1,374	157	144
Reallocation of noncontrolling interest	$ 0		5,938				(5,938)
Equity, shares at Mar. 31, 2023	156,829,793	156,830,000
Equity, value at Mar. 31, 2023	$ 8,306,484	$ 1,568	$ 6,549,314	$ (467,159)	$ (2,722)	$ (18,214)	$ 691,627	$ 1,552,070

Stockholders' Equity / Partners' Capital Narrative (Details) $ in Millions			3 Months Ended
	Feb. 01, 2023 shares	May 22, 2020 USD ($) yr	Mar. 31, 2023 shares	Dec. 31, 2022 shares	Jun. 02, 2017 USD ($)
Class of Stock [Line Items]
Common Stock, Shares, Outstanding			156,829,793	156,757,867
General Partners' Capital Account, Units Outstanding (in units)			1,754,892
Limited Partners' Capital Account, Units Outstanding (in units)			155,074,901
Options exercised			0
Shares of Common Stock issued in connection with redemption of an equal number of OP Units (in shares)			5,188
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period	49,359
ATM Program [Member]
Class of Stock [Line Items]
At The Market Stock Offering Program Aggregate Value Of Common Stock \| $		$ 600.0			$ 600.0
At Market Stock Offering Program Maximum Length Of Sale (in years) \| yr		3

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Net income	$ 105,628	$ 176,957
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	208,734	177,624
Amortization of right of use assets - operating leases	652	529
Non-cash compensation expense	26,262	21,235
Loss (income) from unconsolidated joint ventures	7,569	(2,189)
Distributions of net cash flow from operations of unconsolidated joint ventures	5,996	6,385
Losses (gains) from investments in securities	(1,665)	2,262
Allowance for current expected credit losses	45	(234)
Non-cash portion of interest expense	7,387	5,960
Gains on sales of real estate	0	(22,701)
Unrealized gain on non-real estate investment	(259)	0
Change in assets and liabilities:
Tenant and other receivables, net	7,518	17,635
Notes receivable, net	0	(8)
Accrued rental income, net	(18,619)	(29,567)
Prepaid expenses and other assets	(97,762)	(71,731)
Lease liabilities - operating leases	(251)	116
Accounts payable and accrued expenses	(8,505)	(31,800)
Accrued interest payable	10,626	(3,933)
Other liabilities	16,565	(12,146)
Tenant leasing costs	(35,911)	(14,904)
Total adjustments	128,382	42,533
Net cash provided by operating activities	234,010	219,490
Cash flows from investing activities:
Acquisitions of real estate	0	(3,580)
Construction in progress	(119,682)	(100,313)
Building and other capital improvements	(39,100)	(26,811)
Tenant improvements	(67,175)	(55,168)
Proceeds from sales of real estate	0	35,397
Capital contributions to unconsolidated joint ventures	(60,745)	(26,293)
Capital distributions from unconsolidated joint ventures	0	20,095
Investment in non-real estate investments	(733)	0
Investments in securities, net	1,843	5,338
Net cash used in investing activities	(285,592)	(151,335)
Cash flows from financing activities:
Borrowings on unsecured line of credit	0	190,000
Repayments of unsecured line of credit	0	(80,000)
Borrowings on unsecured term loan	1,200,000	0
Repayment of unsecured term loan	(730,000)	0
Deferred financing costs	(6,213)	(359)
Net activity from equity transactions	586	(332)
Dividends and distributions	(171,270)	(170,488)
Contributions from noncontrolling interests in property partnerships	7,555	849
Distributions to noncontrolling interests in property partnerships	(21,606)	(26,640)
Net cash provided by (used in) financing activities	279,052	(86,970)
Net increase (decrease) in cash and cash equivalents and cash held in escrows	227,470	(18,815)
Cash and cash equivalents and cash held in escrows, beginning of period	736,812	501,158
Cash and cash equivalents and cash held in escrows, end of period	964,282	482,343
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of period	690,333	452,692
Cash held in escrows, beginning of period	46,479	48,466
Cash and cash equivalents, end of period	918,952	436,271
Cash held in escrows,end of period	45,330	46,072
Supplemental disclosures:
Cash paid for interest	125,698	111,904
Interest capitalized	10,589	13,740
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(56,391)	(34,946)
Change in real estate included in accounts payable and accrued expenses	11,692	16,907
Dividends and distributions declared but not paid	171,427	170,869
Conversions of noncontrolling interests to stockholders’ equity	195	5,028
Issuance of restricted securities to employees and non-employee directors	46,516	46,082
Boston Properties Limited Partnership
Net income	107,490	179,378
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	206,872	175,886
Amortization of right of use assets - operating leases	652	529
Non-cash compensation expense	26,262	21,235
Loss (income) from unconsolidated joint ventures	7,569	(2,189)
Distributions of net cash flow from operations of unconsolidated joint ventures	5,996	6,385
Losses (gains) from investments in securities	(1,665)	2,262
Allowance for current expected credit losses	45	(234)
Non-cash portion of interest expense	7,387	5,960
Gains on sales of real estate	0	(23,384)
Unrealized gain on non-real estate investment	(259)	0
Change in assets and liabilities:
Tenant and other receivables, net	7,518	17,635
Notes receivable, net	0	(8)
Accrued rental income, net	(18,619)	(29,567)
Prepaid expenses and other assets	(97,762)	(71,731)
Lease liabilities - operating leases	(251)	116
Accounts payable and accrued expenses	(8,505)	(31,800)
Accrued interest payable	10,626	(3,933)
Other liabilities	16,565	(12,146)
Tenant leasing costs	(35,911)	(14,904)
Total adjustments	126,520	40,112
Net cash provided by operating activities	234,010	219,490
Cash flows from investing activities:
Acquisitions of real estate	0	(3,580)
Construction in progress	(119,682)	(100,313)
Building and other capital improvements	(39,100)	(26,811)
Tenant improvements	(67,175)	(55,168)
Proceeds from sales of real estate	0	35,397
Capital contributions to unconsolidated joint ventures	(60,745)	(26,293)
Capital distributions from unconsolidated joint ventures	0	20,095
Investment in non-real estate investments	(733)	0
Investments in securities, net	1,843	5,338
Net cash used in investing activities	(285,592)	(151,335)
Cash flows from financing activities:
Borrowings on unsecured line of credit	0	190,000
Repayments of unsecured line of credit	0	(80,000)
Borrowings on unsecured term loan	1,200,000	0
Repayment of unsecured term loan	(730,000)	0
Deferred financing costs	(6,213)	(359)
Net activity from equity transactions	586	(332)
Dividends and distributions	(171,270)	(170,488)
Contributions from noncontrolling interests in property partnerships	7,555	849
Distributions to noncontrolling interests in property partnerships	(21,606)	(26,640)
Net cash provided by (used in) financing activities	279,052	(86,970)
Net increase (decrease) in cash and cash equivalents and cash held in escrows	227,470	(18,815)
Cash and cash equivalents and cash held in escrows, beginning of period	736,812	501,158
Cash and cash equivalents and cash held in escrows, end of period	964,282	482,343
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of period	690,333	452,692
Cash held in escrows, beginning of period	46,479	48,466
Cash and cash equivalents, end of period	918,952	436,271
Cash held in escrows,end of period	45,330	46,072
Supplemental disclosures:
Cash paid for interest	125,698	111,904
Interest capitalized	10,589	13,740
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(55,142)	(34,946)
Change in real estate included in accounts payable and accrued expenses	11,692	16,907
Dividends and distributions declared but not paid	171,427	170,869
Conversions of noncontrolling interests to stockholders’ equity	195	5,028
Issuance of restricted securities to employees and non-employee directors	$ 46,516	$ 46,082

Debt	3 Months Ended
Debt	Mar. 31, 2023
Debt Disclosure [Abstract]
Unsecured Debt Disclosure	6. Debt Unsecured Term Loan On January 4, 2023, BPLP entered into a credit agreement that provided for a $1.2 billion unsecured term loan facility (the “2023 Unsecured Term Loan”). Under the credit agreement, BPLP may, at any time prior to the maturity date, increase total commitments by up to an additional $300.0 million in aggregate principal amount by increasing the existing 2023 Unsecured Term Loan or incurring one or more additional term loans, in each case, subject to syndication of the increase and other conditions. The 2023 Unsecured Term Loan matures on May 16, 2024, with one 12-month extension option, subject to customary conditions. Upon entry into the credit agreement, BPLP exercised its option to draw $1.2 billion under the 2023 Unsecured Term Loan, a portion of which was used to repay in full the $730.0 million outstanding under its prior unsecured credit agreement (the “2022 Unsecured Term Loan”), which was scheduled to mature on May 16, 2023. There was no prepayment penalty associated with the repayment of the 2022 Unsecured Term Loan. At BPLP’s option, loans under the 2023 Unsecured Term Loan will bear interest at a rate per annum equal to (1) a base rate equal to the greatest of (a) the Federal Funds rate plus 0.5%, (b) the administrative agent’s prime rate, (c) Term SOFR for a one-month period plus 1.00%, and (d) 1.00%, in each case, plus a margin ranging from 0 to 60 basis points based on BPLP’s credit rating; or (2) a rate equal to adjusted Term SOFR with a one-month period plus a margin ranging from 75 to 160 basis points based on BPLP’s credit rating. Based on BPLP’s credit rating upon entry into the credit agreement, the base rate margin is 0 basis points and the Term SOFR margin is 0.85%. As of March 31, 2023, the 2023 Unsecured Term Loan bears interest at a rate equal to adjusted Term SOFR plus 0.85% (See Note 13). At March 31, 2023, BPLP had $1.2 billion outstanding under the 2023 Unsecured Term Loan.

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-URI https://asc.fasb.org/topic&trid=2208564

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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+ Details

Segment Information

3 Months Ended

Mar. 31, 2023

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

10. Segment Information

The following tables present reconciliations of Net Income Attributable to Boston Properties, Inc. to the Company’s share of Net Operating Income and Net Income Attributable to Boston Properties Limited Partnership to the Company’s share of Net Operating Income for the three months ended March 31, 2023 and 2022.

BXP


	Three months ended March 31,
	2023		2022
	(in thousands)
Net income attributable to Boston Properties, Inc.	$	77,890	$	143,047
Add:


Noncontrolling interest—common units of the Operating Partnership	9,078		16,361
Noncontrolling interests in property partnerships	18,660		17,549
Interest expense	134,207		101,228


Net operating income from unconsolidated joint ventures	40,756		37,321

Depreciation and amortization expense	208,734		177,624
Transaction costs	911		—
Payroll and related costs from management services contracts	5,235		4,065
General and administrative expense	55,802		43,194
Less:
Net operating income attributable to noncontrolling interests in property partnerships	47,097		47,055
Unrealized gain on non-real estate investment	259		—
Gains (losses) from investments in securities	1,665		(2,262)

Interest and other income (loss)	10,941		1,228

Gains on sales of real estate	—		22,701
Income (loss) from unconsolidated joint ventures	(7,569)		2,189
Direct reimbursements of payroll and related costs from management services contracts	5,235		4,065
Development and management services revenue	8,980		5,831
Company’s share of Net Operating Income	$	484,665	$	459,582

BPLP


	Three months ended March 31,
	2023		2022
	(in thousands)
Net income attributable to Boston Properties Limited Partnership	$	88,830	$	161,829
Add:


Noncontrolling interests in property partnerships	18,660		17,549
Interest expense	134,207		101,228


Net operating income from unconsolidated joint ventures	40,756		37,321

Depreciation and amortization expense	206,872		175,886
Transaction costs	911		—
Payroll and related costs from management services contracts	5,235		4,065
General and administrative expense	55,802		43,194
Less:
Net operating income attributable to noncontrolling interests in property partnerships	47,097		47,055
Unrealized gain on non-real estate investment	259		—
Gains (losses) from investments in securities	1,665		(2,262)

Interest and other income (loss)	10,941		1,228

Gains on sales of real estate	—		23,384
Income (loss) from unconsolidated joint ventures	(7,569)		2,189
Direct reimbursements of payroll and related costs from management services contracts	5,235		4,065
Development and management services revenue	8,980		5,831
Company’s share of Net Operating Income	$	484,665	$	459,582

Net operating income (“NOI”) is a non-GAAP financial measure equal to net income attributable to Boston Properties, Inc. and net income attributable to Boston Properties Limited Partnership, as applicable, the most directly comparable GAAP financial measures, plus (1) net income attributable to noncontrolling interests, interest expense, depreciation and amortization expense, transaction costs, payroll and related costs from management services contracts and corporate general and administrative expense less (2) unrealized gain on non-real estate investment, gains (losses) from investments in securities, interest and other income (loss), gains on sales of real estate, income (loss) from unconsolidated joint ventures, direct reimbursements of payroll and related costs from management services contracts and development and management services revenue. The Company believes NOI is useful to investors as a performance measure and believes it provides useful information to investors regarding its results of operations and financial condition because, when compared across periods, it reflects the impact on operations from trends in occupancy rates, rental rates, operating costs and acquisition and development activity on an unleveraged basis, providing perspective not immediately apparent from net income attributable to Boston Properties, Inc. and net income attributable to Boston Properties Limited Partnership. 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), less 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, as defined above, also does not include its share of losses from early extinguishment of debt from unconsolidated joint ventures and unrealized loss on derivative instruments, both of which are included within Income (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. Interest expense, depreciation and amortization expense, transaction costs, payroll and related costs from management services contracts, corporate general and administrative expense, unrealized gain on non-real estate investment, gains (losses) from investments in securities, interest and other income (loss), gains on sales of real estate, income (loss) from unconsolidated joint ventures, direct reimbursements of payroll and related costs from management services contracts and development and management services revenue are not included in NOI and are provided as reconciling items to the Company’s reconciliations of its share of NOI to net income.

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. The Company also presents information for each segment by property type, including Premier Workplace (which includes office, life sciences and retail), Residential and Hotel.

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

For the three months ended March 31, 2023:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	269,951		$	—		$	258,192		$	136,093		$	14,258		$	90,664		$	769,158
Residential	4,049			—			—			3,642			—			4,035			11,726
Hotel	8,101			—			—			—			—			—			8,101
Total	282,101			—			258,192			139,735			14,258			94,699			788,985
% of Grand Totals	35.76		%	—		%	32.72		%	17.71		%	1.81		%	12.00		%	100.00		%
Rental Expenses:
Premier Workplace	100,049			—			102,485			46,085			2,960			34,266			285,845
Residential	1,552			—			—			2,173			—			1,738			5,463
Hotel	6,671			—			—			—			—			—			6,671
Total	108,272			—			102,485			48,258			2,960			36,004			297,979
% of Grand Totals	36.34		%	—		%	34.39		%	16.20		%	0.99		%	12.08		%	100.00		%
Net operating income	$	173,829		$	—		$	155,707		$	91,477		$	11,298		$	58,695		$	491,006
% of Grand Totals	35.41		%	—		%	31.71		%	18.63		%	2.30		%	11.95		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(10,817)			—			(36,280)			—			—			—			(47,097)
Add: Company’s share of net operating income from unconsolidated joint ventures	8,577			13,225			3,650			3,464			1,846			9,994			40,756
Company’s share of net operating income	$	171,589		$	13,225		$	123,077		$	94,941		$	13,144		$	68,689		$	484,665
% of Grand Totals	35.41		%	2.73		%	25.39		%	19.59		%	2.71		%	14.17		%	100.00		%

_______________

For the three months ended March 31, 2022:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	242,078		$	—		$	256,870		$	132,375		$	—		$	95,565		$	726,888
Residential	3,596			—			—			2,391			—			6,979			12,966
Hotel	4,557			—			—			—			—			—			4,557
Total	250,231			—			256,870			134,766			—			102,544			744,411
% of Grand Totals	33.61		%	—		%	34.51		%	18.10		%	—		%	13.78		%	100.00		%
Rental Expenses:
Premier Workplace	90,528			—			96,340			43,408			—			33,547			263,823
Residential	1,437			—			—			1,868			—			3,127			6,432
Hotel	4,840			—			—			—			—			—			4,840
Total	96,805			—			96,340			45,276			—			36,674			275,095
% of Grand Totals	35.19		%	—		%	35.02		%	16.46		%	—		%	13.33		%	100.00		%
Net operating income	$	153,426		$	—		$	160,530		$	89,490		$	—		$	65,870		$	469,316
% of Grand Totals	32.69		%	—		%	34.21		%	19.07		%	—		%	14.03		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(11,735)			—			(35,320)			—			—			—			(47,055)
Add: Company’s share of net operating income (loss) from unconsolidated joint ventures	9,693			13,757			(156)			3,181			1,955			8,891			37,321
Company’s share of net operating income	$	151,384		$	13,757		$	125,054		$	92,671		$	1,955		$	74,761		$	459,582
% of Grand Totals	32.94		%	2.99		%	27.21		%	20.16		%	0.43		%	16.27		%	100.00		%

_______________

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8933-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8736-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e9054-108599

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 15
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8657-108599

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126901519&loc=d3e8721-108599

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-URI https://asc.fasb.org/topic&trid=2134510

+ Details

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $6,832,119 and $6,789,029 at March 31, 2023 and December 31, 2022, respectively)	$ 25,559,720	$ 25,389,663
Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at March 31, 2023 and December 31, 2022, respectively)	237,503	237,510
Less: accumulated depreciation (amounts related to VIEs of $(1,405,167) and $(1,381,401) at March 31, 2023 and December 31, 2022, respectively)	(6,424,547)	(6,298,082)
Cash and cash equivalents (amounts related to VIEs of $233,981 and $259,658 at March 31, 2023 and December 31, 2022, respectively)	918,952	690,333
Tenant and other receivables, net (amounts related to VIEs of $13,108 and $16,521 at March 31, 2023 and December 31, 2022, respectively)	85,603	81,389
Accrued rental income, net (amounts related to VIEs of $375,008 and $367,138 at March 31, 2023 and December 31, 2022, respectively)	1,297,767	1,276,580
Deferred charges, net (amounts related to VIEs of $172,077 and $176,597 at March 31, 2023 and December 31, 2022, respectively)	720,174	733,282
Prepaid expenses and other assets (amounts related to VIEs of $40,737 and $11,647 at March 31, 2023 and December 31, 2022, respectively)	141,933	43,589
Mortgage notes payable, net (amounts related to VIEs of $3,273,553 and $3,272,368 at March 31, 2023 and December 31, 2022, respectively)	3,273,553	3,272,368
Lease liabilities - finance leases (amounts related to VIEs of $20,641 and $20,604 at March 31, 2023 and December 31, 2022, respectively)	250,567	249,335
Accounts payable and accrued expenses (amounts related to VIEs of $37,595 and $29,466 at March 31, 2023 and December 31, 2022, respectively)	397,798	417,545
Other liabilities (amounts related to VIEs of $114,694 and $114,232 at March 31, 2023 and December 31, 2022, respectively)	$ 465,276	$ 450,918
Reedemable deferred stock units, units	103,454	97,853
Limited Partners' Capital Account, Units Outstanding (in units)	155,074,901
General Partners' Capital Account, Units Outstanding (in units)	1,754,892
Excess stock, par value	$ 0.01	$ 0.01
Excess stock, shares authorized	150,000,000	150,000,000
Excess stock, shares outstanding	0	0
Excess stock, shares issued	0	0
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock / units, shares / units issued (in shares / units)	0	0
Preferred stock / units, shares / units outstanding (in shares / units)	0	0
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	156,908,693	156,836,767
Common Stock, Shares, Outstanding	156,829,793	156,757,867
Treasury common stock at cost, shares	78,900	78,900
Boston Properties Limited Partnership
Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $6,832,119 and $6,789,029 at March 31, 2023 and December 31, 2022, respectively)	$ 25,193,455	$ 25,022,149
Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at March 31, 2023 and December 31, 2022, respectively)	237,503	237,510
Less: accumulated depreciation (amounts related to VIEs of $(1,405,167) and $(1,381,401) at March 31, 2023 and December 31, 2022, respectively)	(6,306,326)	(6,180,474)
Cash and cash equivalents (amounts related to VIEs of $233,981 and $259,658 at March 31, 2023 and December 31, 2022, respectively)	918,952	690,333
Tenant and other receivables, net (amounts related to VIEs of $13,108 and $16,521 at March 31, 2023 and December 31, 2022, respectively)	85,603	81,389
Accrued rental income, net (amounts related to VIEs of $375,008 and $367,138 at March 31, 2023 and December 31, 2022, respectively)	1,297,767	1,276,580
Deferred charges, net (amounts related to VIEs of $172,077 and $176,597 at March 31, 2023 and December 31, 2022, respectively)	720,174	733,282
Prepaid expenses and other assets (amounts related to VIEs of $40,737 and $11,647 at March 31, 2023 and December 31, 2022, respectively)	141,933	43,589
Mortgage notes payable, net (amounts related to VIEs of $3,273,553 and $3,272,368 at March 31, 2023 and December 31, 2022, respectively)	3,273,553	3,272,368
Lease liabilities - finance leases (amounts related to VIEs of $20,641 and $20,604 at March 31, 2023 and December 31, 2022, respectively)	250,567	249,335
Accounts payable and accrued expenses (amounts related to VIEs of $37,595 and $29,466 at March 31, 2023 and December 31, 2022, respectively)	397,798	417,545
Other liabilities (amounts related to VIEs of $114,694 and $114,232 at March 31, 2023 and December 31, 2022, respectively)	$ 465,276	$ 450,918
Reedemable deferred stock units, units	103,454	97,853
Limited Partners' Capital Account, Units Outstanding (in units)	155,074,901	155,008,185
General Partners' Capital Account, Units Outstanding (in units)	1,754,892	1,749,682
NonControlling Interest Redeemable Partnership Units Common Units Shares Outstanding	16,527,638	16,531,172
NonControlling Interest Redeemable Partnership Units Common Units Long Term Incentive Units At Redemption Value Shares Outstanding	2,131,785	1,679,175
Variable Interest Entity, Primary Beneficiary [Member]
Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $6,832,119 and $6,789,029 at March 31, 2023 and December 31, 2022, respectively)	$ 6,832,119	$ 6,789,029
Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at March 31, 2023 and December 31, 2022, respectively)	21,000	21,000
Less: accumulated depreciation (amounts related to VIEs of $(1,405,167) and $(1,381,401) at March 31, 2023 and December 31, 2022, respectively)	(1,405,167)	(1,381,401)
Cash and cash equivalents (amounts related to VIEs of $233,981 and $259,658 at March 31, 2023 and December 31, 2022, respectively)	233,981	259,658
Tenant and other receivables, net (amounts related to VIEs of $13,108 and $16,521 at March 31, 2023 and December 31, 2022, respectively)	13,108	16,521
Accrued rental income, net (amounts related to VIEs of $375,008 and $367,138 at March 31, 2023 and December 31, 2022, respectively)	375,008	367,138
Deferred charges, net (amounts related to VIEs of $172,077 and $176,597 at March 31, 2023 and December 31, 2022, respectively)	172,077	176,597
Prepaid expenses and other assets (amounts related to VIEs of $40,737 and $11,647 at March 31, 2023 and December 31, 2022, respectively)	40,737	11,647
Mortgage notes payable, net (amounts related to VIEs of $3,273,553 and $3,272,368 at March 31, 2023 and December 31, 2022, respectively)	3,273,553	3,272,368
Lease liabilities - finance leases (amounts related to VIEs of $20,641 and $20,604 at March 31, 2023 and December 31, 2022, respectively)	20,641	20,604
Accounts payable and accrued expenses (amounts related to VIEs of $37,595 and $29,466 at March 31, 2023 and December 31, 2022, respectively)	37,595	29,466
Other liabilities (amounts related to VIEs of $114,694 and $114,232 at March 31, 2023 and December 31, 2022, respectively)	114,694	114,232
Variable Interest Entity, Primary Beneficiary [Member] \| Boston Properties Limited Partnership
Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $6,832,119 and $6,789,029 at March 31, 2023 and December 31, 2022, respectively)	6,832,119	6,789,029
Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at March 31, 2023 and December 31, 2022, respectively)	21,000	21,000
Less: accumulated depreciation (amounts related to VIEs of $(1,405,167) and $(1,381,401) at March 31, 2023 and December 31, 2022, respectively)	(1,405,167)	(1,381,401)
Cash and cash equivalents (amounts related to VIEs of $233,981 and $259,658 at March 31, 2023 and December 31, 2022, respectively)	233,981	259,658
Tenant and other receivables, net (amounts related to VIEs of $13,108 and $16,521 at March 31, 2023 and December 31, 2022, respectively)	13,108	16,521
Accrued rental income, net (amounts related to VIEs of $375,008 and $367,138 at March 31, 2023 and December 31, 2022, respectively)	375,008	367,138
Deferred charges, net (amounts related to VIEs of $172,077 and $176,597 at March 31, 2023 and December 31, 2022, respectively)	172,077	176,597
Prepaid expenses and other assets (amounts related to VIEs of $40,737 and $11,647 at March 31, 2023 and December 31, 2022, respectively)	40,737	11,647
Mortgage notes payable, net (amounts related to VIEs of $3,273,553 and $3,272,368 at March 31, 2023 and December 31, 2022, respectively)	3,273,553	3,272,368
Lease liabilities - finance leases (amounts related to VIEs of $20,641 and $20,604 at March 31, 2023 and December 31, 2022, respectively)	20,641	20,604
Accounts payable and accrued expenses (amounts related to VIEs of $37,595 and $29,466 at March 31, 2023 and December 31, 2022, respectively)	37,595	29,466
Other liabilities (amounts related to VIEs of $114,694 and $114,232 at March 31, 2023 and December 31, 2022, respectively)	$ 114,694	$ 114,232

Organization (Details) ft² in Millions	3 Months Ended	12 Months Ended
Organization (Details) ft² in Millions	Mar. 31, 2023 ft² Real_Estate_Properties yr shares	Dec. 31, 2022
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
2012 OPP Units and Vested MYLTIPs
Real Estate Properties [Line Items]
Vesting Period	3 years
Construction in Progress
Real Estate Properties [Line Items]
Number of real estate properties	15
Net Rentable Area (in sf) \| ft²	4.0
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	192
Net Rentable Area (in sf) \| ft²	54.5
Office and Life Sciences Building [Member]
Real Estate Properties [Line Items]
Number of real estate properties	171
Office and Life Sciences Building [Member] \| Construction in Progress
Real Estate Properties [Line Items]
Number of real estate properties	12
Retail Site [Member]
Real Estate Properties [Line Items]
Number of real estate properties	14
Retail Site [Member] \| Construction in Progress
Real Estate Properties [Line Items]
Number of real estate properties	2
Residential Building
Real Estate Properties [Line Items]
Number of real estate properties	6
Residential Building \| Construction in Progress
Real Estate Properties [Line Items]
Number of real estate properties	1
Hotel [Member]
Real Estate Properties [Line Items]
Number of real estate properties	1
Boston Properties Limited Partnership
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)	89.40%	89.60%

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

3 Months Ended

Mar. 31, 2023

Mar. 31, 2022

Schedule of Equity Method Investments [Line Items]

$ 803,200

$ 754,307

Expenses

911

208,734

177,624

568,661

499,978

Gains on sales of real estate

(134,207)

(101,228)

22,701

Income (Loss) from Equity Method Investments

105,628

176,957

(7,569)

2,189

Schedule of Equity Method Investments [Line Items]

^[1]

151,423

124,491

Expenses

Operating

57,206

45,641

49,978

44,664

107,258

90,305

Losses from early extinguishment of debt

(1,327)

Unrealized loss on derivative instruments

(57,250)

(30,373)

(10,610)

Company's share of net income

(23,695)

2,486

(6,902)

3,394

Basis differential

^[2]

(667)

(1,205)

Income (Loss) from Equity Method Investments

(7,569)

2,189

Straight Line Rent Adjustments

6,300

27,500

Above and below market rent adjustments, net

200

100

Colorado Center [Member] | Unconsolidated Joint Ventures [Member]

Straight Line Rent Adjustments

$ 300

$ 100

[1]	Includes straight-line rent adjustments of approximately $6.3 million and $27.5 million for the three months ended March 31, 2023 and 2022, respectively.
[2]	Includes straight-line rent adjustments of approximately $0.3 million and $0.1 million for the three months ended March 31, 2023 and 2022, respectively. Also includes net above-/below-market rent adjustments of approximately $0.2 million and $0.1 million for the three months ended March 31, 2023 and 2022, respectively.

Noncontrolling Interests (Narrative) (Details) - Boston Properties Limited Partnership	Mar. 31, 2023 shares
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	16,527,638
LTIP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	2,131,785
2012 OPP and 2013-2020 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	514,854
MYLTIP 2021
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	350,989
MYLTIP 2022
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	253,453
MYLTIP 2023
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	322,053

Leases (Tables)

3 Months Ended

Mar. 31, 2023

Lessor, Lease, Description [Line Items]

Operating Lease, Lease Income [Table Text Block]

The following table summarizes the components of lease revenue recognized for its operating and sales-type leases during the three months ended March 31, 2023 and 2022 included within the Company's Consolidated Statements of Operations (in thousands):


	Three months ended March 31,
Lease Revenue	2023		2022
Fixed contractual payments	$	621,646	$	599,607
Variable lease payments	135,003		118,513
Sales-type lease income	226		—
	$	756,875	$	718,120

Sales-type Lease, Lease Income


	Three months ended March 31,
Lease Revenue	2023		2022
Fixed contractual payments	$	621,646	$	599,607
Variable lease payments	135,003		118,513
Sales-type lease income	226		—
	$	756,875	$	718,120

Earnings Per Share / Common Unit

3 Months Ended

Mar. 31, 2023

Earnings Per Share [Abstract]

Earnings Per Share / Common Unit

11. Earnings Per Share / Common Unit

BXP

The following table provides a reconciliation of both the net income attributable to Boston Properties, Inc. 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. 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 BXP and BPLP’s LTIP Units, 2012 OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic EPS of BXP using the two-class method. Participating securities are included in the computation of diluted EPS of BXP using the if-converted method if the impact is dilutive. Because the 2012 OPP Units and 2013 - 2020 MYLTIP Units required, and the 2021 - 2023 MYLTIP Units require, BXP to outperform absolute and/or relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, BXP excludes such units from the diluted EPS calculation. Other potentially dilutive common shares, including stock options, restricted stock and other securities of BPLP that are exchangeable for BXP’s Common Stock, and the related impact on earnings, are considered when calculating diluted EPS.


	Three months ended March 31, 2023
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc.	$	77,890	156,803	$	0.50


Effect of Dilutive Securities:
Stock Based Compensation	—		240	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc.	$	77,890	157,043	$	0.50

	Three months ended March 31, 2022
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:


Net income attributable to Boston Properties, Inc.	$	143,047	156,650	$	0.91
Effect of Dilutive Securities:
Stock Based Compensation	—		354	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc.	$	143,047	157,004	$	0.91

BPLP

The following table provides a reconciliation of both the net income attributable to Boston Properties Limited Partnership 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 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 BXP and BPLP’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 - 2020 MYLTIP Units required, and the 2021 - 2023 MYLTIP Units require, BXP to outperform absolute and/or relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, BPLP 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 17,849,000 and 17,626,000 redeemable common units for the three months ended March 31, 2023 and 2022, respectively.


	Three months ended March 31, 2023
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership	$	88,830	174,652	$	0.51


Effect of Dilutive Securities:
Stock Based Compensation	—		240	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership	$	88,830	174,892	$	0.51

	Three months ended March 31, 2022
	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	$	161,829	174,276	$	0.93


Effect of Dilutive Securities:
Stock Based Compensation	—		354	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership	$	161,829	174,630	$	0.93

Real Estate

3 Months Ended

Mar. 31, 2023

Real Estate [Abstract]

Real Estate

3. Real Estate

BXP

Real estate consisted of the following at March 31, 2023 and December 31, 2022 (in thousands):


	March 31, 2023		December 31, 2022
Land	$	5,189,287	$	5,189,811
Right of use assets - finance leases	237,503		237,510
Right of use assets - operating leases	166,699		167,351
Land held for future development (1)	626,137		721,501
Buildings and improvements	15,783,962		15,820,724
Tenant improvements	3,291,322		3,200,743
Furniture, fixtures and equipment	50,242		50,310
Construction in progress	618,770		406,574
Total	25,963,922		25,794,524
Less: Accumulated depreciation	(6,424,547)		(6,298,082)
	$	19,539,375	$	19,496,442

_______________

(1)Includes pre-development costs.

BPLP

Real estate consisted of the following at March 31, 2023 and December 31, 2022 (in thousands):


	March 31, 2023		December 31, 2022
Land	$	5,094,578	$	5,095,102
Right of use assets - finance leases	237,503		237,510
Right of use assets - operating leases	166,699		167,351
Land held for future development (1)	626,137		721,501
Buildings and improvements	15,512,406		15,547,919
Tenant improvements	3,291,322		3,200,743
Furniture, fixtures and equipment	50,242		50,310
Construction in progress	618,770		406,574
Total	25,597,657		25,427,010
Less: Accumulated depreciation	(6,306,326)		(6,180,474)
	$	19,291,331	$	19,246,536

_______________

(1)Includes pre-development costs.

Developments/Redevelopments

On January 5, 2023, the Company commenced the development of 290 Binney Street, an approximately 566,000 net rentable square foot laboratory/life sciences project in Cambridge, Massachusetts. Concurrent with the commencement of this project, the Kendall Center Blue Parking Garage was taken out of service and demolished to support the development of this project. 290 Binney Street is 100% pre-leased to AstraZeneca.

On January 30, 2023, the Company commenced the redevelopment of 300 Binney Street at Kendall Center in Cambridge, Massachusetts. 300 Binney Street consisted of an approximately 195,000 net rentable square foot premier workplace that is being redeveloped into approximately 236,000 net rentable square feet of laboratory/life sciences space. BXP and BPLP recognized approximately $11.0 million of depreciation expense during the three months ended March 31, 2023 associated with the acceleration of depreciation on the assets being removed from service and demolished as part of the redevelopment of the property. The project is 100% pre-leased to the Broad Institute.

Comprehensive Text Block List (Policies)	3 Months Ended
Comprehensive Text Block List (Policies)	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	BXP does not have any other significant assets, liabilities or operations, other than its investment in BPLP, nor does it have employees of its own. BPLP, not BXP, generally executes all significant business relationships other than transactions involving securities of BXP. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income.The accompanying interim financial statements are unaudited; however, the financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information and in conjunction with the rules and regulations of the Securities and Exchange Commission (the “SEC”). Accordingly, they do not include all of the disclosures required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting solely of normal recurring matters) necessary for a fair statement of the financial statements for these interim periods have been included. The results of operations for the interim periods are not necessarily indicative of the results to be obtained for other interim periods or for the full fiscal year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosure required by GAAP. These financial statements should be read in conjunction with the Company’s financial statements and notes thereto contained in the Company’s Annual Report in the Company’s Form 10-K for its fiscal year ended December 31, 2022.
Consolidation, Variable Interest Entity, Policy	Consolidated VIEs are those for which the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE.

Earnings Per Share / Common Unit (Tables)

3 Months Ended

Mar. 31, 2023

Entity Information [Line Items]

Computation Of Basic And Diluted Earnings Per Share / Unit


	Three months ended March 31, 2023
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc.	$	77,890	156,803	$	0.50


Effect of Dilutive Securities:
Stock Based Compensation	—		240	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc.	$	77,890	157,043	$	0.50

	Three months ended March 31, 2022
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:


Net income attributable to Boston Properties, Inc.	$	143,047	156,650	$	0.91
Effect of Dilutive Securities:
Stock Based Compensation	—		354	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc.	$	143,047	157,004	$	0.91

Computation Of Basic And Diluted Earnings Per Share / Unit

Entity Information [Line Items]


	Three months ended March 31, 2023
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership	$	88,830	174,652	$	0.51


Effect of Dilutive Securities:
Stock Based Compensation	—		240	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership	$	88,830	174,892	$	0.51

	Three months ended March 31, 2022
	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	$	161,829	174,276	$	0.93


Effect of Dilutive Securities:
Stock Based Compensation	—		354	—
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership	$	161,829	174,630	$	0.93

Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	$ 78,544	$ 78,576
Sales-type lease receivable, net	13,028	12,811
Mortgage notes payable, net	3,273,553	3,272,368
Unsecured senior notes, net	10,240,967	10,237,968
Unsecured line of credit	0	0
Unsecured term loan, net	1,194,916	730,000
Carrying Amount [Member]
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	78,544	78,576
Sales-type lease receivable, net	13,028	12,811
Total	91,572	91,387
Mortgage notes payable, net	3,273,553	3,272,368
Unsecured senior notes, net	10,240,967	10,237,968
Unsecured line of credit	0	0
Unsecured term loan, net	1,194,916	730,000
Total	14,709,436	14,240,336
Estimated Fair Value [Member]
Summary Of Significant Accounting Policies [Line Items]
Related party note receivable, net	79,472	79,220
Sales-type lease receivable, net	13,086	13,045
Total	92,558	92,265
Mortgage notes payable, net	2,826,826	2,744,479
Unsecured senior notes, net	8,759,487	9,135,512
Unsecured line of credit	0	0
Unsecured term loan, net	1,200,000	730,000
Total	$ 12,786,313	$ 12,609,991

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the company's common shareholders / unitholders	$ 77,890	$ 143,047
Noncontrolling interest-common units of the Operating Partnership	(9,078)	(16,361)
Noncontrolling interest in property partnerships	(18,660)	(17,549)
Interest expense	(134,207)	(101,228)
Company's share of net operating income from joint ventures	(491,006)	(469,316)
Depreciation and amortization expense	(208,734)	(177,624)
Transaction costs	(911)	0
General and administrative expense	(55,802)	(43,194)
Unrealized Gain (Loss) on Investments	(259)	0
Gains (losses) from investments in securities	(1,665)	2,262
Interest and other income (loss)	(10,941)	(1,228)
Gains on sales of real estate	0	(22,701)
Income (loss) from unconsolidated joint ventures	7,569	(2,189)
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	77,890	143,047
Noncontrolling interest-common units of the Operating Partnership	9,078	16,361
Noncontrolling interest in property partnerships	18,660	17,549
Interest expense	134,207	101,228
Depreciation and amortization expense	208,734	177,624
Transaction costs	911	0
Operating expense	5,235	4,065
General and administrative expense	55,802	43,194
Gains (losses) from investments in securities	1,665	(2,262)
Interest and other income (loss)	10,941	1,228
Gains on sales of real estate	0	22,701
Income (loss) from unconsolidated joint ventures	(7,569)	2,189
Other revenue	5,235	4,065
Company's share of Net Operating Income	484,665	459,582
Unconsolidated Joint Ventures [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense	(57,250)	(30,373)
Losses from early extinguishment of debt	0	1,327
Depreciation and amortization expense	(49,978)	(44,664)
Transaction costs	(74)	0
Income (loss) from unconsolidated joint ventures	7,569	(2,189)
Unconsolidated Joint Ventures [Member] \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	40,756	37,321
Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the company's common shareholders / unitholders	88,830	161,829
Noncontrolling interest in property partnerships	(18,660)	(17,549)
Interest expense	(134,207)	(101,228)
Depreciation and amortization expense	(206,872)	(175,886)
Transaction costs	(911)	0
General and administrative expense	(55,802)	(43,194)
Unrealized Gain (Loss) on Investments	(259)	0
Gains (losses) from investments in securities	(1,665)	2,262
Interest and other income (loss)	(10,941)	(1,228)
Gains on sales of real estate	0	(23,384)
Income (loss) from unconsolidated joint ventures	7,569	(2,189)
Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the company's common shareholders / unitholders	88,830	161,829
Noncontrolling interest in property partnerships	18,660	17,549
Interest expense	134,207	101,228
Depreciation and amortization expense	206,872	175,886
Transaction costs	911	0
Operating expense	5,235	4,065
General and administrative expense	55,802	43,194
Gains (losses) from investments in securities	1,665	(2,262)
Interest and other income (loss)	10,941	1,228
Gains on sales of real estate	0	23,384
Other revenue	5,235	4,065
Company's share of Net Operating Income	484,665	459,582
Management Service [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	(8,980)	(5,831)
Management Service [Member] \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	8,980	5,831
Management Service [Member] \| Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	(8,980)	(5,831)
Management Service [Member] \| Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	8,980	5,831
Noncontrolling interest - property partnerships [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	47,097	47,055
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	47,097	47,055
Unrealized Gain (Loss) on Investments	259	0
Noncontrolling interest - property partnerships [Member] \| Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	47,097	47,055
Unrealized Gain (Loss) on Investments	259	0
Income (loss) from unconsolidated joint ventures	$ (7,569)	$ 2,189

Leases (Details) - USD ($) $ in Thousands	3 Months Ended
Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Mar. 31, 2022
Leases [Abstract]
Fixed contractual payments	$ 621,646	$ 599,607
Variable lease payments	135,003	118,513
Sales-type lease income	226	0
Lease	$ 756,875	$ 718,120

Leases

3 Months Ended

Mar. 31, 2023

Leases [Abstract]

Lessor, Operating Leases [Text Block]

4. Leases

The Company estimates the collectability of its accrued rent and accounts receivable balances related to lease revenue. When evaluating the collectability of these accrued rent and accounts receivable balances, management considers tenant creditworthiness, current economic trends, including the impact of the COVID-19 pandemic on tenants’ businesses, and changes in tenants’ payment patterns, on a lease-by-lease basis. If the Company determines that the accrued rent and/or accounts receivable balances are no longer probable of collection then the balances are written-off and the lease is recognized on a cash basis.

If applicable, information related to write-offs of accrued rent, net balances and accounts receivable, net balances and reinstatements of accrued rent balances for the Company’s unconsolidated joint ventures can be found in Note 5.

Lessor


	Three months ended March 31,
Lease Revenue	2023		2022
Fixed contractual payments	$	621,646	$	599,607
Variable lease payments	135,003		118,513
Sales-type lease income	226		—
	$	756,875	$	718,120

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

3 Months Ended

Mar. 31, 2023

USD ($)

ft²

payments

Dec. 31, 2022

USD ($)

Schedule of Equity Method Investments [Line Items]

$ (465,276)

$ (450,918)

Investments In Affiliates Subsidiaries Associates And Joint Ventures net

1,752,617

1,715,911

^[1]

1,671,124

1,630,485

Schedule of Equity Method Investments [Line Items]

Square 407 Limited Partnership [Member]

$ (81,500)

(85,400)

Schedule of Equity Method Investments [Line Items]

Market Square North

50.00%

BP/CRF Metropolitan Square LLC [Member]

^[1]

$ (6,097)

(6,198)

Schedule of Equity Method Investments [Line Items]

Metropolitan Square

20.00%

901 New York Avenue LLC [Member]

^[1]

$ (38,782)

(37,629)

Schedule of Equity Method Investments [Line Items]

901 New York Avenue

^[2]

25.00%

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

^[1]

$ (12,311)

$ (12,493)

Schedule of Equity Method Investments [Line Items]

WP Project Developer LLC [Member]

50.00%

Schedule of Equity Method Investments [Line Items]

Wisconsin Place Land and Infrastructure

^[3]

33.33%

500 North Capitol Venture LLC [Member]

^[1]

$ 31,723

$ 31,971

Schedule of Equity Method Investments [Line Items]

500 North Capitol Street, NW

30.00%

501 K Street LLC [Member]

^[1]

$ (8,941)

(9,185)

Schedule of Equity Method Investments [Line Items]

1001 6th Street

^[4]

50.00%

Potential additonal payments to joint venture partner | payments

^[1]

$ 43,661

42,922

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

520,000

Podium Developer LLC [Member]

Schedule of Equity Method Investments [Line Items]

The Hub on Causeway - Podium

50.00%

Residential Tower Developer LLC [Member]

^[1]

$ 45,622

46,839

Schedule of Equity Method Investments [Line Items]

Hub50House

50.00%

Hotel Tower Developer LLC [Member]

^[1]

$ 42,046

45,414

Schedule of Equity Method Investments [Line Items]

The Hub on Causeway - Hotel Air Rights

50.00%

Office Tower Developer LLC [Member]

^[1]

$ 12,582

12,366

Schedule of Equity Method Investments [Line Items]

50.00%

Office Tower Developer LLC

^[1]

$ 59,811

59,716

Schedule of Equity Method Investments [Line Items]

1265 Main Office JV LLC [Member]

100 Causeway Street

Schedule of Equity Method Investments [Line Items]

1265 Main Street

50.00%

BNY Tower Holdings LLC [Member]

^[1]

$ 3,605

3,465

Schedule of Equity Method Investments [Line Items]

Dock 72

^[5]

50.00%

CA-Colorado Center LLC[Member]

^[1]

$ 15,362

19,921

Schedule of Equity Method Investments [Line Items]

Colorado Center

50.00%

7750 Wisconsin Avenue LLC [Member]

^[1]

$ 234,635

233,862

Schedule of Equity Method Investments [Line Items]

7750 Wisconsin Avenue

50.00%

BP-M 3HB Venture LLC [Member]

^[1]

$ 51,549

52,152

Schedule of Equity Method Investments [Line Items]

3 Hudson Boulevard

25.00%

Schedule of Equity Method Investments [Line Items]

^[1]

$ 115,966

116,397

SMBP Venture LP [Member]

Santa Monica Business Park

55.00%

Platform 16 Holdings LP [Member]

^[1]

$ 161,786

164,735

Schedule of Equity Method Investments [Line Items]

Platform 16

^[6]

55.00%

Gateway Portfolio Holdings LLC [Member]

^[1]

$ 171,010

158,109

Schedule of Equity Method Investments [Line Items]

Gateway Commons

50.00%

Rosecrans-Sepulveda Partners 4, LLC

^[1]

$ 337,535

324,038

Schedule of Equity Method Investments [Line Items]

Beach Cities Media Campus

50.00%

Entity Owning Land And Infrastructure Of Project [Member]

^[1]

$ 26,987

27,000

Schedule of Equity Method Investments [Line Items]

Schedule of Equity Method Investments [Line Items]

33.33%

Safeco Plaza REIT LLC

Safeco Plaza

^[7]

33.67%

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

^[1]

$ 68,196

69,785

Schedule of Equity Method Investments [Line Items]

Schedule of Equity Method Investments [Line Items]

33.00%

360 PAS Holdco LLC

360 Park Avenue South

^[8]

42.21%

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

^[1]

$ 116,828

114,992

Schedule of Equity Method Investments [Line Items]

360 PAS Holdco LLC | Joint Venture Partner [Member] | Scenario, Plan

35.79%

Schedule of Equity Method Investments [Line Items]

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

58.00%

Schedule of Equity Method Investments [Line Items]

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

5.837%

Schedule of Equity Method Investments [Line Items]

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

1.00%

Schedule of Equity Method Investments [Line Items]

PR II BXP Reston Gateway LLC

1.00%

Schedule of Equity Method Investments [Line Items]

Reston Next Residential

^[9]

20.00%

PR II BXP Reston Gateway LLC | Joint Venture Partner [Member] | Scenario, Plan

^[1]

$ 11,431

11,351

Schedule of Equity Method Investments [Line Items]

Schedule of Equity Method Investments [Line Items]

80.00%

751 Gateway Holdings LLC

751 Gateway

49.00%

Schedule of Equity Method Investments [Line Items]

^[1]

$ 85,430

80,714

200 Fifth Avenue JV LLC

200 Fifth Avenue

26.69%

ABXP Worldgate Investments LLC

^[1]

$ 114,919

$ 120,083

Schedule of Equity Method Investments [Line Items]

13100 and 13150 Worldgate Drive

50.00%