Deferred stock units outstanding

No definition available.

Name:	bxp_DeferredStockUnitsOutstanding
Namespace Prefix:	bxp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number Of Non Employee Directors Electing To Receive Deferred Stock Units

+ References

No definition available.

+ Details

Name:	bxp_NumberOfNonEmployeeDirectorsElectingToReceiveDeferredStockUnits
Namespace Prefix:	bxp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- 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

- Definition

Sum of the carrying values as of the balance sheet date of obligations incurred through that date, including liabilities incurred and payable to vendors for goods and services received, taxes, interest, rent and utilities, compensation costs, payroll taxes and fringe benefits (other than pension and postretirement obligations), contractual rights and obligations, and statutory obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.15)
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(1),(5))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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

- Definition

Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_CommonStockSharesIssued
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

Name:	us-gaap_RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

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

- Definition

Number of stock bought back by the entity at the exercise price or redemption price.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644

+ Details

Name:	us-gaap_StockRedeemedOrCalledDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=bxp_DirectorCessationMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_DirectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_ImmediateFamilyMemberOfManagementOrPrincipalOwnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=bxp_RealEstateBrokerageFirmMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related Party Transactions (Details) $ in Thousands		12 Months Ended
Related Party Transactions (Details) $ in Thousands	Sep. 03, 2019 shares	Dec. 31, 2020 USD ($) Vehicles shares	Dec. 31, 2019 USD ($) Vehicles shares	Dec. 31, 2018 USD ($)	May 21, 2019 shares
Related Party Transaction [Line Items]
Number Of Non Employee Directors Electing To Receive Deferred Stock Units \| Vehicles		7
Separate Unrestricted Cash For Deferred Compensation Plan.		$ 39,500	$ 36,700
Liability for directors		$ 336,264	$ 377,553
Common stock, shares issued \| shares		155,797,725	154,869,198
OP Units for redemption (in shares) \| shares	4,917
Deferred stock units outstanding \| Vehicles		72,966	60,676
Director Cessation Member [Member]
Related Party Transaction [Line Items]
Common stock, shares issued \| shares					17,949
Director
Related Party Transaction [Line Items]
Separate Unrestricted Cash For Deferred Compensation Plan.		$ 800	$ 700
Liability for directors		800	700
Immediate Family Member of Management or Principal Owner
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party		914	21	$ 921
Real Estate Brokerage Firm
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party		$ 3,400	$ 2,600