Investment in Unconsolidated Ventures (Financial Position of Unconsolidated Real Estate Ventures) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Financial position of the Real Estate Ventures
Company's share of equity (Company's basis)	$ 133,292	$ 115,807
Unconsolidated real estate ventures [Member]
Financial position of the Real Estate Ventures
Net property	840,292	846,643
Other Assets	113,449	110,520
Other Liabilities	46,225	48,798
Debt	679,026	745,830
Equity	228,490	162,535
Company's share of equity (Company's basis)	$ 133,292	$ 115,807