Interest and Other Investment Income (Loss), Net (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total Interest and Other Investment Income, net	$ (260,945)	$ 148,784	$ 235,267
Impairment Losses On Marketable Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total Interest and Other Investment Income, net	(224,937)	0	0
Marketable Equity Securities Derivative Positions [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total Interest and Other Investment Income, net	(75,815)	12,984	130,153
Mezzanine Loans Receivable [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total Interest and Other Investment Income, net	13,861	14,023	10,319
Marketable Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total Interest and Other Investment Income, net	11,979	29,587	25,772
Mark to Market of deferred Compensation Plan [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total Interest and Other Investment Income, net	6,809	1,658	8,049
Mezzanine Loans Loss Accrual [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total Interest and Other Investment Income, net	0	82,744	53,100
Other Investment Income [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total Interest and Other Investment Income, net	$ 7,158	$ 7,788	$ 7,874