Fair Value Measurements (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Fair value assets measured on non recurring basis unobservable input reconciliation
Total Impairment Gain (Losses) on Investment properties	$ 17,458	$ 30,208	$ 27,887	$ 58,175
Total Impairment Gain (Losses) on Investment in unconsolidated entities			4,200	0
Total Impairment Gain (Losses)	17,458	30,208	32,087	58,175
Using Significant Other Unobservable Inputs (Level 3) [Member]
Fair value assets measured on non recurring basis unobservable input reconciliation
Fair Value Measurements, Investment properties	80,871	157,059	223,508	224,309
Fair Value Measurements, Investment in unconsolidated entities			16,914	0
Fair Value Measurements, Total	$ 80,871	$ 157,059	$ 240,422	$ 224,309