Investment in Unconsolidated Ventures (Financial Position of Unconsolidated Real Estate Ventures) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Company's share of equity (Company's Basis)	$ 186,042		$ 180,512
Austin Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Company's share of equity (Company's Basis)	(1,200)
Unconsolidated Real Estate Ventures [Member]
Schedule of Equity Method Investments [Line Items]
Net property	1,081,064		965,475
Other assets	153,348		164,152
Other liabilities	68,031		49,442
Debt	792,919		699,860
Equity	373,462		380,325
Company's share of equity (Company's Basis)	$ 186,042	[1]	$ 180,512	[1]

[1] (a) This amount includes the effect of the basis difference between the Company's historical cost basis and the basis recorded at the Real Estate Venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials occur from the impairment of investments, purchases of third party interests in existing Real Estate Ventures and upon the transfer of assets that were previously owned by the Company into a Real Estate Venture. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the Real Estate Venture level.