Investment in Unconsolidated Joint Ventures - Unconsolidated Joint Ventures (Details) (Unconsolidated Properties, USD $) In Thousands, unless otherwise specified	Jun. 30, 2014 Property	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Number of real estate properties	7
Equity method investments	$ 131,443	$ 151,162
Austin Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership percentage in equity investments (in percent)	40.00%
Number of real estate properties	5
Equity method investments	75,813	42,501
US Airways Building
Schedule of Equity Method Investments [Line Items]
Ownership percentage in equity investments (in percent)	74.58%
Number of real estate properties	1
Equity method investments	40,371	15,490
7000 Central Park JV LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage in equity investments (in percent)	40.00%
Number of real estate properties	1
Equity method investments	$ 15,259	$ 93,171

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

Reference 1: 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

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- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=16385135&loc=d3e33749-111570

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- Definition

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

+ References

No definition available.

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- Details

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