Interest and Other Investment Income (Loss), Net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Total Interest and Other Investment Income, Net	$ (49,172)	$ 7,998	$ (33,507)	$ 125,097
Marketable Equity Securities Derivative Positions [Member]
Total Interest and Other Investment Income, Net	(58,732)	(6,762)	(57,687)	10,401
Mezzanine Loans Loss Accrual [Member]
Total Interest and Other Investment Income, Net	0	0	0	82,744
Marketable Securities [Member]
Total Interest and Other Investment Income, Net	4,846	7,669	11,093	15,336
Mark to Market of deferred Compensation Plan [Member]
Total Interest and Other Investment Income, Net	24	1,793	4,151	6,745
Mezzanine Loans Receivable [Member]
Total Interest and Other Investment Income, Net	3,165	3,083	6,015	5,727
Other Investment Income [Member]
Total Interest and Other Investment Income, Net	$ 1,525	$ 2,215	$ 2,921	$ 4,144