v2.4.0.8

Noncontrolling Interests (Redeemable Preferred Units) (Narrative) (Details) (USD $) |  | 3 Months Ended | 6 Months Ended |  |  |  |  |  |  |  | 3 Months Ended |  | 6 Months Ended |  |  |  | 6 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2013 Noncontrolling Interests [Member] | Jun. 30, 2013 Series Two Preferred Units [Member] | Jun. 30, 2013 Series Two Preferred Units [Member] Noncontrolling Interests [Member] | May 15, 2013 Series Two Preferred Units [Member] Noncontrolling Interests [Member] | May 14, 2013 Series Two Preferred Units [Member] Noncontrolling Interests [Member] | Feb. 15, 2013 Series Two Preferred Units [Member] Noncontrolling Interests [Member] | Dec. 31, 2012 Series Two Preferred Units [Member] Noncontrolling Interests [Member] | Dec. 31, 2011 Series Two Preferred Units [Member] Noncontrolling Interests [Member] | Dec. 31, 2010 Series Two Preferred Units [Member] Noncontrolling Interests [Member] | Dec. 31, 2009 Series Two Preferred Units [Member] Noncontrolling Interests [Member] | Jun. 30, 2013 series four preferred units [Member] | Aug. 07, 2013 series four preferred units [Member] | Jun. 30, 2013 series four preferred units [Member] Noncontrolling Interests [Member] | May 29, 2013 series four preferred units [Member] Noncontrolling Interests [Member] D | May 15, 2013 series four preferred units [Member] Noncontrolling Interests [Member] | Feb. 15, 2013 series four preferred units [Member] Noncontrolling Interests [Member] | Jun. 30, 2013 Redemption Year Two Thousand Fourteen [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum Redeemable On Redemption Dates Preferred Units |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 1,007,662
Series Two Preferred Units (in shares) | 995,997 |  | 995,997 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Liquidation preference percentage |  |  | 6.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred Units Liquidation Preference |  | $ 50.00 | $ 50.00 |  |  |  |  |  |  |  | $ 50.00 | $ 50.00 | $ 50.00 |  |  |  |
First opportunity to redeem Series Four Preferred Units (in days) |  |  |  |  |  |  |  |  |  |  |  |  |  | 30 |  |  |
Operating Units liquidation preference (in dollars per share) |  |  | $ 38.10 |  |  |  |  |  |  |  |  |  |  |  |  |  |
OP Units for each Preferred Unit (in shares) |  | 1.312336 | 1.312336 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Series Two Preferred Units Redemption Price |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 50.00
Dates Series Two Preferred Unit Holders Can Require Redemption From Operating Partnership |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | May 12, 2014
Maximum portion that may be required for redemption of total |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.1666666667
Distributions to Series Two Preferred Units (in dollars per share) |  |  |  | $ 0.85302 |  | $ 0.85302 |  |  |  |  |  |  |  |  | $ 0.25 | $ 0.25 |
Series Four Preferred Units (in shares) | 1,221,527 |  |  |  |  |  |  |  |  |  |  |  | 1,221,527 |  |  |  |
Series Four Preferred Units Annual Dividend Payable Rate |  |  |  |  |  |  |  |  |  |  | 2.00% |  | 2.00% |  |  |  |
Number Of Holders Exercises |  |  |  |  | 0 |  | 0 | 0 | 0 | 0 |  |  |  |  |  |  |

X
- Definition Cash Distributions To Preferred Unitholders Per Unit + References No definition available. + Details
Name: | bxp_CashDistributionsToPreferredUnitholdersPerUnit
Namespace Prefix: | bxp_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Dates Series Two Preferred Unit Holders Can Require Redemption From Operating Partnership + References No definition available. + Details
Name: | bxp_DatesSeriesTwoPreferredUnitHoldersCanRequireRedemptionFromOperatingPartnership
Namespace Prefix: | bxp_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition First opportunity to redeem Series Four Preferred Units (in days) + References No definition available. + Details
Name: | bxp_FirstopportunitytoredeemSeriesFourPreferredUnitsindays
Namespace Prefix: | bxp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Maximum Portion That May Be Required For Redemption Of Total + References No definition available. + Details
Name: | bxp_MaximumPortionThatMayBeRequiredForRedemptionOfTotal
Namespace Prefix: | bxp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum Redeemable On Redemption Dates Preferred Units + References No definition available. + Details
Name: | bxp_MaximumRedeemableOnRedemptionDatesPreferredUnits
Namespace Prefix: | bxp_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number Of Holders Exercises + References No definition available. + Details
Name: | bxp_NumberOfHoldersExercises
Namespace Prefix: | bxp_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Operating Units liquidation preference + References No definition available. + Details
Name: | bxp_OperatingUnitsConversionRate
Namespace Prefix: | bxp_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Op Units For Each Preferred Unit + References No definition available. + Details
Name: | bxp_OpUnitsForEachPreferredUnit
Namespace Prefix: | bxp_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Preferred Units Liquidation Preference + References No definition available. + Details
Name: | bxp_PreferredUnitsLiquidationPreference
Namespace Prefix: | bxp_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Preferred Units Liquidation Preference Percentage + References No definition available. + Details
Name: | bxp_PreferredUnitsLiquidationPreferencePercentage
Namespace Prefix: | bxp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Series Four Preferred Units + References No definition available. + Details
Name: | bxp_SeriesFourPreferredUnits
Namespace Prefix: | bxp_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Series Four Preferred Units Annual Dividend Payable Rate + References No definition available. + Details
Name: | bxp_Seriesfourpreferredunitsannualdividendpayablerate
Namespace Prefix: | bxp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Series Two Preferred Units + References No definition available. + Details
Name: | bxp_SeriesTwoPreferredUnits
Namespace Prefix: | bxp_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Series Two Preferred Units Redemption Price + References No definition available. + Details
Name: | bxp_SeriesTwoPreferredUnitsRedemptionPrice
Namespace Prefix: | bxp_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_ConsolidationLessThanWhollyOwnedSubsidiaryParentOwnershipInterestEffectsOfChangesNetLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration