v2.4.0.6

Investments in Unconsolidated Joint Ventures (Investments in Unconsolidated Joint Ventures) (Details)

3 Months Ended

Mar. 31, 2013

Square 407 Limited Partnership [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Market Square North

Equity Method Investment, Ownership Percentage

50.00%

The Metropolitan Square Associates LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Metropolitan Square

Equity Method Investment, Ownership Percentage

51.00%

BP/CRF 901 New York Avenue LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

901 New York Avenue

^[1]

Equity Method Investment, Ownership Percentage

25.00%

^[1]

WP Project Developer LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Wisconsin Place Land and Infrastructure

^[2]

Equity Method Investment, Ownership Percentage

33.30%

^[2]

RBP Joint Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Eighth Avenue and 46th Street

^[3]

Equity Method Investment, Ownership Percentage

50.00%

^[3]

Boston Properties Office Value-Added Fund, L.P. [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Mountain View Research and Technology Parks

^[1],[4]

Equity Method Investment, Ownership Percentage

39.50%

^[1],[4]

Annapolis Junction NFM, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Annapolis Junction

^[5]

Equity Method Investment, Ownership Percentage

50.00%

^[5]

Number of real estate properties

2

Number of buildings under construction

1

Parcels of undeveloped land

2

767 Venture, LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

The General Motors Building

Equity Method Investment, Ownership Percentage

60.00%

2 GCT Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

Two Grand Central Tower

^[6]

Equity Method Investment, Ownership Percentage

60.00%

^[6]

540 Madison Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

540 Madison Avenue

Equity Method Investment, Ownership Percentage

60.00%

125 West 55th Street Venture LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

125 West 55th Street

^[4]

Equity Method Investment, Ownership Percentage

60.00%

^[4]

500 North Capitol LLC [Member]

Schedule of Equity Method Investments [Line Items]

Properties

500 North Capitol Street, NW

Equity Method Investment, Ownership Percentage

30.00%

Entity Owning Land And Infrastructure Of Project [Member]

Schedule of Equity Method Investments [Line Items]

Equity Method Investment, Ownership Percentage

33.30%

[1]	The Company’s economic ownership can increase based on the achievement of certain return thresholds.
[2]	The Company’s wholly-owned entity that owns the office component of the project also owns a 33.3% interest in the entity owning the land and infrastructure of the project.
[3]	This property is not in operation and consists of assembled land.
[4]	See Note 12.
[5]	Comprised of two buildings, one building under construction and two undeveloped land parcels.
[6]	The property was sold on October 25, 2011. As of March 31, 2013, the investment is comprised of undistributed cash.

X

- Definition

Name of Joint Venture Property

+ References

No definition available.

+ Details

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X

- Definition

Number of buildings under construction

+ References

No definition available.

+ Details

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X

- Definition

Parcels of undeveloped land

+ References

No definition available.

+ Details

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X

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-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.



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571



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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (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.

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X

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

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X

- Details

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