v2.4.0.8

Noncontrolling Interests (Narrative) (Details) | Sep. 30, 2014
--- | ---
Noncontrolling Interests [Member] |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |
Operating Partnership (OP) Units (in shares) | 16,456,297
Long-Term Incentive Plan (LTIP) Units (in shares) | 1,505,386
Series Four Preferred Units (in shares) | 40,440
OPP Units 2012 [Member] |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |
Outperformance awards in LTIP Units (in shares) | 394,590
MYLTIP [Member] |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |
2013 MYLTIP | 314,974
MYLTIP 2014 [Member] |
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items] |
2014 MYLTIP | 483,555

X
- Definition 2013 MYLTIP + References No definition available. + Details
Name: | bxp_A2013Myltip
Namespace Prefix: | bxp_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Long Term Incentive Plan Units + References No definition available. + Details
Name: | bxp_LongTermIncentivePlanUnits
Namespace Prefix: | bxp_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Outperformance Awards Long Term Incentive Plan Units + References No definition available. + Details
Name: | bxp_OutperformanceAwardsLongTermIncentivePlanUnits
Namespace Prefix: | bxp_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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 2014 MYLTIP + References No definition available. + Details
Name: | bxp_TwothousandfourteenMYLTIP
Namespace Prefix: | bxp_
Data Type: | xbrli:sharesItemType
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