Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years)

No definition available.

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

- Definition

Number of interest rate swap agreements entered into

+ References

No definition available.

+ Details

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

- Definition

Term of anticipated mortgage loan (in years)

+ References

No definition available.

+ Details

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

- Definition

Time period when the effects of the swaps may be reclassified into earnings (in months)

+ References

No definition available.

+ Details

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

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

The aggregate fair value of assets needed to immediately settle the derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624258-113959

+ Details

Name:	us-gaap_AssetsNeededForImmediateSettlementAggregateFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

- Definition

Average fixed interest rate related to the group of interest rate derivatives.

+ References

No definition available.

+ Details

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

- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

+ Details

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

- Definition

The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4H

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624258-113959

+ Details

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

- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bxp_HedgingIssuerAxis=bxp_OperatingPartnershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	bxp_HedgingIssuerAxis=bxp_SevensixsevenFifthPartnersLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Derivative Instruments and Hedging Activities (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) swaps yr mo	Jun. 30, 2014 USD ($)	Aug. 07, 2015
Debt Instrument [Line Items]
Amount of gain (loss) related to the effective portion recognized in other comprehensive income (loss)	$ 15,639	$ 0	$ 12,106	$ 0
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, Net Liability Position, Aggregate Fair Value	12,100		12,100
Assets Needed for Immediate Settlement, Aggregate Fair Value	12,100		12,100
Notional Amount	$ 475,000		475,000
Amount of gain (loss) related to the effective portion recognized in other comprehensive income (loss)			$ 12,100
Time period when the effects of the swaps may be reclassified into earnings (in months) \| mo			12
Operating Partnership [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Number of interest rate swap agreements entered into (swap contracts) \| swaps			8
Term of anticipated mortgage loan (in years) \| yr			10
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) \| yr			10
Average Fixed Interest Rate	2.458%		2.458%
Notional Amount	$ 325,000		$ 325,000
767 Fifth Partners LLC [Member]
Debt Instrument [Line Items]
Ownership Percentage by the Company					60.00%
767 Fifth Partners LLC [Member] \| Interest Rate Swap [Member]
Debt Instrument [Line Items]
Number of interest rate swap agreements entered into (swap contracts) \| swaps			5
Term of anticipated mortgage loan (in years) \| yr			10
Maximum period of hedging exposure to the variability in future cash flows for forecasted transactions (in years) \| yr			10
Average Fixed Interest Rate	2.793%		2.793%
Notional Amount	$ 150,000		$ 150,000