Fair Value Measurements (Details) (USD $)				12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2010 Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Fair Value, Measurements, Nonrecurring [Member]	Dec. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Long Lived Assets Held And Used [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2010 Fair Value, Measurements, Recurring [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 1 [Member]	Dec. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 2 [Member]	Dec. 31, 2011 Fair Value, Measurements, Nonrecurring [Member] Fair Value, Inputs, Level 3 [Member]	Dec. 31, 2011 Parent Company [Member]	Dec. 31, 2010 Parent Company [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments in real estate partnerships	$ 386,882,000	$ 428,592,000												$ 1,893,000			$ 1,893,000	$ 386,882,000	$ 428,592,000
Equity Method Investment, Other than Temporary Impairment				(4,580,000)
Assets, Fair Value Disclosure, Nonrecurring														7,413,000	0	0	7,413,000
Assets Held-for-sale, Long Lived, Fair Value Disclosure														5,520,000	0	0	5,520,000
Fair Value, Option, Changes in Fair Value, Gain (Loss)				(16,423,000)	(11,843,000)
Total Assets, Fair Value														7,413,000	0	0	7,413,000
Notes Receivable, Fair Value												35,300,000
Trading Securities, Fair Value Disclosure						21,713,000	20,891,000	21,713,000	20,891,000	0	0	0	0
Notes Payable, Fair Value			2,100,000,000									2,100,000,000
Total			$ 0			$ 21,713,000	$ 20,891,000	$ 21,713,000	$ 20,891,000	$ 0	$ 0	$ 0