Investment in Unconsolidated Ventures (Summary of Results of Operations of Unconsolidated Real Estate Ventures) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Summary of results of operations of Real Estate Ventures
Income (Loss) from Equity Method Investments	$ 2,741	$ 3,775	$ 5,305
Unconsolidated real estate ventures [Member]
Summary of results of operations of Real Estate Ventures
Revenue	164,013	145,867	118,923
Operating expenses	70,775	63,715	44,942
Interest expense, net	41,633	42,032	37,505
Depreciation and amortization	50,241	39,172	32,703
Net income	1,364	948	3,773
Income (Loss) from Equity Method Investments	$ 2,741	$ 3,775	$ 5,305