XML 73 R58.htm IDEA: XBRL DOCUMENT
v3.25.3

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) - USD ($) $ in Thousands | Aug. 27, 2025 | Aug. 26, 2025 | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | --- | --- | ---
Noncontrolling Interest [Line Items] |  |  |  |
Noncontrolling Interest in Limited Partnerships |  |  | $ 1,954,777 | $ 1,933,545
343 Madison Avenue |  |  |  |
Noncontrolling Interest [Line Items] |  |  |  |
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests | $ 43,500 |  |  |
Gain on Sale of Investments | $ 0 |  |  |
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage |  | 55.00% |  |
343 Madison Avenue | Minority Interest |  |  |  |
Noncontrolling Interest [Line Items] |  |  |  |
Subsidiary, Ownership Percentage, Noncontrolling Owner | 45.00% |  |  |

X
- Definition The difference between the carrying value and the sale price of an investment. A gain would be recognized when the sale price of the investment is greater than the carrying value of the investment. This element refers to the Gain included in earnings and not to the cash proceeds of the sale. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -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://www.xbrl.org/2009/role/commonPracticeRef -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/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 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 942 -SubTopic 220 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1 + Details
Name: | us-gaap_GainOnSaleOfInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Decrease in noncontrolling interest (for example, but not limited to, redeeming or purchasing the interests of noncontrolling shareholders, issuance of shares (interests) by the non-wholly owned subsidiary to the parent entity for other than cash, and a buyback of shares (interest) by the non-wholly owned subsidiary from the noncontrolling interests). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 810 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 23 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-23 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 24 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481231/810-10-45-24 + Details
Name: | us-gaap_MinorityInterestDecreaseFromRedemptions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Carrying amount of the equity interests owned by noncontrolling partners of a limited partnership included in the entity's consolidated financial statements. + References No definition available. + Details
Name: | us-gaap_MinorityInterestInLimitedPartnerships
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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 No definition available. + Details
Name: | us-gaap_MinorityInterestLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481203/810-10-50-5A + Details
Name: | us-gaap_VariableInterestEntityOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=bxp_ThreeFourThreeMadisonAvenueMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=bxp_MinorityInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |