Fair Value Measurements (Details Textual) (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 and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of the investment properties	$ 17,458	$ 30,208	$ 27,887	$ 58,175
Fair Value Measurements (Additional Textual) [Abstract]
Weighted average effective rate, fair value of debt instruments			5.19%
Impairment charge			4,200
Fair Value Measurements, Investment in unconsolidated entities	16,914		16,914
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment properties, capitalization rates			9.00%
Investment properties, discount rates			10.00%
Equity method investments capitalization rate fair value			11.25%
Equity method investments discount rate fair value			11.00%
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment properties, capitalization rates			7.25%
Investment properties, discount rates			7.50%
Equity method investments capitalization rate fair value			8.00%
Equity method investments discount rate fair value			10.00%
Segment, Continuing Operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of the investment properties			27,887	17,314
Segment, Discontinued Operations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impairment of the investment properties			$ 0	$ 40,861