Interest and Other Investment Income (Loss), Net (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Total Interest and Other Investment Income, net	$ 148,826	$ 235,315	$ (116,350)
Mezzanine Loans Loss Accrual [Member]
Total Interest and Other Investment Income, net	82,744	53,100	(190,738)
Marketable Securities [Member]
Total Interest and Other Investment Income, net	29,587	25,772	25,908
Mezzanine Loans Receivable [Member]
Total Interest and Other Investment Income, net	14,023	10,319	32,181
Marketable Equity Securities Derivative Positions [Member]
Total Interest and Other Investment Income, net	12,984	130,153	0
Mark to Market of deferred Compensation Plan [Member]
Total Interest and Other Investment Income, net	1,658	8,049	9,506
Impairment Losses On Marketable Securities [Member]
Total Interest and Other Investment Income, net	0	0	(3,361)
Other Investment Income [Member]
Total Interest and Other Investment Income, net	$ 7,830	$ 7,922	$ 10,154