Investment in Real Estate (Details 3) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Long-lived Assets Held for Sale	$ 52,057	$ 288,369
Long-lived Assets Held and Used	22,090	3,905
Long-lived Assets Held for Sale	(6,121)	(193,226)
Long-lived Assets Held and Used	(896)	(1,326)
Long-lived Assets impairment	(7,017)	(194,552)
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	0	0
Long-lived Assets Held and Used	0	0
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	0	0
Long-lived Assets Held and Used	0	0
Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Long-lived Assets Held for Sale	52,057	288,369
Long-lived Assets Held and Used	$ 22,090	$ 3,905