Land sold (in acres)

No definition available.

Name:	bxp_Landsoldinacres
Namespace Prefix:	bxp_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of apartment units

+ References

No definition available.

+ Details

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

- Definition

Rental revenue supoprt payments to buyer maximum

+ References

No definition available.

+ Details

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

- Definition

Sale Price Of Sold Property

+ References

No definition available.

+ Details

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

- Definition

Area of land held.

+ References

No definition available.

+ Details

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

- Definition

This element represents the amount of gain (loss) on sale of properties during the reporting period gross of the applicable income taxes realized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 974

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-15.(a)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6875705&loc=d3e641549-123027

+ Details

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

- 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

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

+ Details

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

- Definition

Cash received from the sale of real estate that is held for investment, that is, it is part of an investing activity during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3179-108585

+ Details

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

- Details

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

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=bxp_ResidencesonTheAvenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=bxp_WashingtonianNorthlandparcelMember
Namespace Prefix:
Data Type:	na
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Period Type:

Real Estate Activity During the Three Months Ended March 31, 2015 (Narrative) (Details) (USD $)	3 Months Ended		0 Months Ended		3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Feb. 19, 2015	Mar. 17, 2015	Mar. 16, 2015
Real Estate Properties [Line Items]
Operating income	$ 206,209,000us-gaap_OperatingIncomeLoss	$ 176,897,000us-gaap_OperatingIncomeLoss
Proceeds from the sales of real estate	194,821,000	0
Gains on sales of real estate	95,084,000	0
Washingtonian North land parcel [Member]
Real Estate Properties [Line Items]
Sale Price Of Sold Property			8,700,000
Proceeds from the sales of real estate			8,300,000
Gains on sales of real estate			3,700,000
Land sold (in acres)			8.5
Area of Land (in acres)			27
Residences on The Avenue [Member]
Real Estate Properties [Line Items]
Operating income		800,000			1,100,000
Rental revenue supoprt payments to buyer maximum				6,000,000
Sale Price Of Sold Property				196,000,000
Proceeds from the sales of real estate				192,500,000
Gains on sales of real estate				$ 91,400,000
Number of apartment units (apartment units)				335
Net Rentable Area (retail space) (in sf)				50,000