Investment in Real Estate (Details 3) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Long-lived Assets Held for Sale	$ 20,470	$ 42,945
Long-lived Assets Held and Used	16,290	95,120
Long-lived Assets Held for Sale	(1,360)	(2,755)
Long-lived Assets Held and Used	(190)	1,894
Long-lived Assets impairment	(1,550)	(861)
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Long-lived Assets Held for Sale
Long-lived Assets Held and Used
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Long-lived Assets Held for Sale
Long-lived Assets Held and Used
Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Long-lived Assets Held for Sale	20,470	42,945
Long-lived Assets Held and Used	$ 16,290	$ 95,120