Carrying Value of Debt Assumed in Sale

No definition available.

Name:	bxp_CarryingValueOfDebtAssumedInSale
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual Sales Price

+ References

No definition available.

+ Details

Name:	bxp_ContractualSalesPrice
Namespace Prefix:	bxp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of apartment units that could potentially be built under an option agreement

+ References

No definition available.

+ Details

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

- Definition

Term of Lease Signed (in years)

+ References

No definition available.

+ Details

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

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Net rentable area for properties owned.

+ References

No definition available.

+ Details

Name:	us-gaap_NetRentableArea
Namespace Prefix:	us-gaap_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of cash outflow for costs that are essential to originate the lease and would not otherwise have been incurred without the lease agreement. Amount includes, but is not limited to, cash outflows to evaluate the lessee's credit condition, guarantees, and collateral and cash outflows for costs incurred in negotiating, processing, and executing the lease agreement.

+ References

No definition available.

+ Details

Name:	us-gaap_PaymentsForLeasingCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=bxp_OnetwosixfiveMainStreetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=bxp_MetropolitianSquareMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=bxp_OwnershippercentageinequitymethodinvestmentjointventurepartnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=bxp_OneFourFiveBroadwayMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LeaseArrangementTypeAxis=bxp_BuildtosuitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=bxp_FuturedevelopmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_MortgageLoansOnRealEstateDescriptionTypeOfPropertyAxis=bxp_RetailPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Subsequent Events subsequent Events (Details) - Subsequent Event [Member] $ in Millions	Oct. 20, 2016 USD ($) ft²	Nov. 07, 2016 ft² yr	Oct. 24, 2016 apartments	Oct. 21, 2016	Oct. 01, 2016 ft²
Subsequent Event [Line Items]
Number of apartment units \| apartments			400
1265 Main Street [Member]
Subsequent Event [Line Items]
Ownership Percentage					50.00%
Net Rentable Area (in sf)					115,000
Metropolitian Square [Member]
Subsequent Event [Line Items]
Ownership Percentage	51.00%			20.00%
Net Rentable Area (in sf)	607,000
Contractual Sales Price \| $	$ 282.4
Carrying Value of Debt Assumed in Sale \| $	133.4
Unfunded leasing costs \| $	$ 14.2
Ownership percentage in equity method investment, joint venture partner [Member] \| Metropolitian Square [Member]
Subsequent Event [Line Items]
Ownership Percentage	49.00%			80.00%
145 Broadway [Member]
Subsequent Event [Line Items]
Net Rentable Area (in sf)		80,000
Term of Lease Signed (in years) \| yr		15
build to suit [Member] \| 145 Broadway [Member]
Subsequent Event [Line Items]
Net Rentable Area (in sf)		476,500
Future development [Member] \| 145 Broadway [Member]
Subsequent Event [Line Items]
Net Rentable Area (in sf)		486,000
Retail Properties [ Member] \| 145 Broadway [Member]
Subsequent Event [Line Items]
Net Rentable Area (in sf)		9,500