Interest and Other Investment Income (Loss), Net (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Total Interest and Other Investment Income (Loss), Net	$ 10,523	$ (30,011)	$ (22,984)	$ 95,086
Marketable Equity Securities Derivative Positions [Member]
Total Interest and Other Investment Income (Loss), Net	4,344	(37,537)	(53,343)	(27,136)
Mezzanine Loans Loss Accrual [Member]
Total Interest and Other Investment Income (Loss), Net	0	0	0	82,744
Marketable Securities [Member]
Total Interest and Other Investment Income (Loss), Net	0	7,605	11,093	22,941
Mark to Market of deferred Compensation Plan [Member]
Total Interest and Other Investment Income (Loss), Net	1,116	(5,243)	5,267	1,502
Mezzanine Loans Receivable [Member]
Total Interest and Other Investment Income (Loss), Net	2,852	3,442	8,867	9,169
Other Investment Income [Member]
Total Interest and Other Investment Income (Loss), Net	$ 2,211	$ 1,722	$ 5,132	$ 5,866