Interest and Other Investment Income (Loss), Net (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Total Interest and Other Investment Income, net	$ 8,007	$ 3,876	$ 125,115	$ 18,580
Marketable Equity Securities Derivative Positions [Member]
Total Interest and Other Investment Income, net	(6,762)	0	10,401	0
Mezzanine Loans Loss Accrual [Member]
Total Interest and Other Investment Income, net	0	(6,900)	82,744	(6,900)
Marketable Securities [Member]
Total Interest and Other Investment Income, net	7,669	7,377	15,336	14,622
Mark to Market of deferred Compensation Plan [Member]
Total Interest and Other Investment Income, net	1,793	(986)	6,745	1,777
Mezzanine Loans Receivable [Member]
Total Interest and Other Investment Income, net	3,083	2,325	5,727	5,040
Other Investment Income [Member]
Total Interest and Other Investment Income, net	$ 2,224	$ 2,060	$ 4,162	$ 4,041