XML 50 R35.htm IDEA: XBRL DOCUMENT
v3.25.3

Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 29, 2025 USD ($) | Dec. 31, 2024 USD ($)
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Separate Unrestricted Cash For Deferred Compensation Plan. | $ 43,400 |  | $ 43,400 |  |  | $ 39,400
Gains from investments in securities | 2,400 | $ 2,198 | 4,635 | $ 4,785 |  |
Prepaid Expense and Other Assets | 137,561 |  | 137,561 |  |  | 70,839
Unsecured commercial paper | $ 750,000 |  | $ 750,000 |  |  | 500,000
Number of VIEs | 11 |  | 11 |  |  |
Impairment loss | $ 68,901 | 0 | $ 68,901 | 13,615 |  |
Commercial Paper |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Unsecured commercial paper | $ 750,000 |  | $ 750,000 |  |  |
Unconsolidated Joint Ventures [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Number of VIEs | 3 |  | 3 |  |  |
Boston Properties Limited Partnership |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Gains from investments in securities | $ 2,400 | 2,198 | $ 4,635 | 4,785 |  |
Prepaid Expense and Other Assets | 137,561 |  | 137,561 |  |  | 70,839
Unsecured commercial paper | 750,000 |  | 750,000 |  |  | 500,000
Impairment loss | 65,988 | 0 | 65,988 | 13,615 |  |
Deferred Compensation, Excluding Share-Based Payments and Retirement Benefits |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Gains from investments in securities | 2,400 | $ 2,200 | 4,600 | $ 4,800 |  |
Environmental Focused Investment Fund |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Prepaid Expense and Other Assets | 9,400 |  | 9,400 |  |  | 7,100
Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Prepaid Expense and Other Assets | $ 51,682 |  | $ 51,682 |  |  | 15,036
Number of VIEs | 8 |  | 8 |  |  |
Variable Interest Entity, Primary Beneficiary [Member] | Boston Properties Limited Partnership |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Prepaid Expense and Other Assets | $ 51,682 |  | $ 51,682 |  |  | $ 15,036
Convertible Debt | 2.00% unsecured exchangeable senior notes |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Debt |  |  |  |  | $ 1,000,000 |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  |  | 2.00% |
Convertible Debt | Boston Properties Limited Partnership | 2.00% unsecured exchangeable senior notes |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Debt |  |  |  |  | $ 1,000,000 |
Debt Instrument, Interest Rate, Stated Percentage |  |  |  |  | 2.00% |
Commercial Real Estate Properties [Member] | Variable Interest Entity, Primary Beneficiary [Member] |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Number of VIEs | 6 |  | 6 |  |  |
Wholly Owned Properties |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Impairment loss | $ 68,900 |  |  |  |  |
Wholly Owned Properties | Boston Properties Limited Partnership |  |  |  |  |  |
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |
Impairment loss | $ 66,000 |  |  |  |  |

X
- Definition Number of VIEs + References No definition available. + Details
Name: | bxp_NumberOfVIEs
Namespace Prefix: | bxp_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Separate Unrestricted Cash For Deferred Compensation Plan. + References No definition available. + Details
Name: | bxp_SeparateUnrestrictedCashForDeferredCompensationPlan
Namespace Prefix: | bxp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Summary Of Significant Accounting Policies [Line Items] + References No definition available. + Details
Name: | bxp_SummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix: | bxp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Carrying value as of the balance sheet date of short-term borrowings using unsecured obligations issued by banks, corporations and other borrowers to investors. The maturities of these money market securities generally do not exceed 270 days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(13)(2)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(a)(3)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
Name: | us-gaap_CommercialPaper
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -SubTopic 10 -Topic 210 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 942 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481139/470-20-50-4 + Details
Name: | us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)(a)(1)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1B -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481139/470-20-50-1B + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of realized and unrealized gain (loss) on investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(9)(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 220 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(7)(c)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2 Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 + Details
Name: | us-gaap_GainLossOnInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The charge against earnings in the period to reduce the carrying amount of real property to fair value. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 230 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 28 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482740/230-10-45-28 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 360 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482099/360-10-50-2 + Details
Name: | us-gaap_ImpairmentOfRealEstate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets. + References No definition available. + Details
Name: | us-gaap_PrepaidExpenseAndOtherAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_CashAndCashEquivalentsAxis=us-gaap_CommercialPaperMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=bxp_UnconsolidatedJointVenturesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=bxp_BostonPropertiesLimitedPartnershipMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTypeOfDeferredCompensationAxis=us-gaap_DeferredCompensationExcludingShareBasedPaymentsAndRetirementBenefitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=bxp_EnvironmentalFocusedInvestmentFundMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_ConvertibleDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=bxp_TwoPointZeroZeroPercentUnsecuredExchangeableSeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=us-gaap_CommercialRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstatePropertiesAxis=us-gaap_WhollyOwnedPropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |