v2.4.0.8

Investments in Unconsolidated Joint Ventures investment in Unconsolidated Joint Ventures (Narrative) (Details) (USD $)	9 Months Ended		0 Months Ended			0 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Apr. 10, 2014 501 K Street [Member] sqft	Sep. 30, 2014 501 K Street [Member] payments sqft		Jun. 23, 2014 Annapolis Junction Building Eight [Member] Y	Apr. 30, 2014 Annapolis Junction Building Eight [Member] sqft	Apr. 10, 2014 joint venture partner [Member] 501 K Street [Member]	Apr. 10, 2014 Company [Member] 501 K Street [Member]	Apr. 30, 2014 Company [Member] Annapolis Junction Building Eight [Member]
Schedule of Equity Method Investments [Line Items]
Debt Instrument, Description of Variable Rate Basis						LIBOR plus 1.50%
Capital contributions to unconsolidated joint ventures	$ 47,767,000	$ 0	$ 39,000,000				$ 5,400,000
Ownership Percentage				50.00%	[1]			50.00%	50.00%	50.00%
Net Rentable Area (in sf)			520,000				125,000
Construction Loan Facility Borrowing Capacity						$ 26,000,000
Debt Instrument, Basis Spread on Variable Rate						1.50%
Maturity Date						Jun. 23, 2017
Number of extensions						2
Extension Option (in years)						1
Potential additonal payments to joint venture partner				2
Minimum square footage to make a potential additional payment to joint venture partner (in sqft)				520,000
[1] Under the joint venture agreement, the partner will be entitled to up to two additional payments from the venture based on increases in total square footage of the project above 520,000 square feet and achieving certain project returns at stabilization.

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Minimum square footage to make a potential additional payment to joint venture partner (in sqft)

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

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The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

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-Topic 230

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