v2.4.0.6

Real Estate Activity During The Three Months Ended March 31, 2012 (Schedule Of Allocation Of The Aggregate Purchase Price Of Acquisition) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 01, 2012 453 Ravendale Drive [Member]	Mar. 13, 2012 100 Federal Street [Member]
Restructuring Cost and Reserve [Line Items]
Land	$ 5,477	$ 131,067
Building and improvements	974	387,321
Tenant improvements	116	48,633
In-place lease intangibles	223	69,530
Above market rents		81
Other assets		4,800
Below market rents	(140)	(22,515)
Accounts payable and accrued expenses		(3,917)
Net assets acquired	$ 6,650	$ 615,000

X

- Definition

The amount of acquisition cost of a business combination allocated to in place lease intangibles.

+ References

No definition available.

+ Details

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

X

- Definition

The amount of acquisition cost of a business combination allocated to above market rents.

+ References

No definition available.

+ Details

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

X

- Definition

The amount of acquisition cost of a business combination allocated to below market rents.

+ References

No definition available.

+ Details

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

X

- Definition

The amount of acquisition cost of a business combination allocated to building and improvements.

+ References

No definition available.

+ Details

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

X

- Definition

Business acquisition purchase price allocation current liabilities accounts payable and accrued liabilities

+ References

No definition available.

+ Details

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

X

- Definition

The amount of acquisition cost of a business combination allocated to land.

+ References

No definition available.

+ Details

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

X

- Definition

The amount of acquisition cost of a business combination allocated to tenant improvements.

+ References

No definition available.

+ Details

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

X

- Definition

Net Assets Acquired

+ References

No definition available.

+ Details

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

X

- Definition

The amount of acquisition cost of a business combination allocated to noncurrent assets of the acquired entity, except for property plant and equipment, intangible assets, and goodwill.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 98-1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 37

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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- Details

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Balance Type:	na
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