Fair value of all asset derivatives designated as cash flow hedging instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4B

+ Details

Name:	us-gaap_CashFlowHedgeDerivativeInstrumentAssetsAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of all liability derivatives designated as cash flow hedging instruments.

+ References

+ Details

Name:	us-gaap_CashFlowHedgeDerivativeInstrumentLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480237/815-40-50-5

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date derivative contract ends, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 55
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480493/946-210-55-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480524/946-210-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13(Column A)(Footnote 3))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5C
-Subparagraph (SX 210.12-13C(Column D))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5C

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5
-Subparagraph (SX 210.12-13(Column F))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5A
-Subparagraph (SX 210.12-13A(Column C))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 5B
-Subparagraph (SX 210.12-13B(Column D))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480032/946-320-S99-5B

+ Details

Name:	us-gaap_DerivativeMaturityDates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1B

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-1A

+ Details

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Indicates whether the entity pays a variable or fixed price on a price risk swap.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeSwapType
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=bxp_ThreeTwoFiveMainStreetThreeFiveFiveMainStreetNinetyBroadwayAndKendallCenterGreenGaragePropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=bxp_SantaMonicaBusinessParkMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=bxp_ThreeTwoFiveMainStreetThreeFiveFiveMainStreetNinetyBroadwayAndKendallCenterGreenGaragePropertiesAndUnsecuredTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=bxp_A2023UnsecuredTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Instruments and Hedging Activities (Details) - Interest Rate Swap - USD ($) $ in Thousands			12 Months Ended
	Dec. 07, 2023	May 02, 2023	Dec. 31, 2023	Dec. 14, 2023	Dec. 31, 2022
Derivative [Line Items]
Derivative, Notional Amount	$ 600,000	$ 1,200,000	$ 2,100,000
Derivative, Maturity Date		May 16, 2024
Fair Value Hedge Assets			$ 1,976		$ 0
325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member]
Derivative [Line Items]
Derivative, Swap Type			Interest Rate Swaps
Derivative, Notional Amount	$ 600,000		$ 600,000
Derivative, Maturity Date	Oct. 26, 2028		Oct. 26, 2028
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value			$ (7,198)
Santa Monica Business Park [Member]
Derivative [Line Items]
Derivative, Swap Type			Interest Rate Swaps
Derivative, Notional Amount			$ 300,000	$ 300,000
Derivative, Maturity Date			Apr. 01, 2025
Fair Value Hedge Assets			$ 6,626
Three Two Five Main Street, Three Five Five Main Street, Ninety Broadway and Kendall Center Green Garage Properties and Unsecured Term Loan
Derivative [Line Items]
Derivative, Notional Amount			1,800,000
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value			$ (4,650)
2023 Unsecured Term Loan
Derivative [Line Items]
Derivative, Swap Type			Interest Rate Swaps
Derivative, Notional Amount			$ 1,200,000
Derivative, Maturity Date			May 16, 2024
Fair Value Hedge Assets			$ 2,548
Minimum [Member] \| 325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate			3.79%
Minimum [Member] \| Santa Monica Business Park [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate			2.661%
Minimum [Member] \| 2023 Unsecured Term Loan
Derivative [Line Items]
Derivative, Fixed Interest Rate			4.638%
Maximum [Member] \| 325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate			3.798%
Maximum [Member] \| Santa Monica Business Park [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate			2.688%
Maximum [Member] \| 2023 Unsecured Term Loan
Derivative [Line Items]
Derivative, Fixed Interest Rate			4.646%