Investments in Affiliates (Details) - Operating Affiliates (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investment, operating affiliates	$ 1,126,875		$ 1,052,729
Equity in net income (loss) in operating affiliates	114,314		103,039		172,474
Operating affiliates
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investment, operating affiliates	281,678		283,878
Equity in net income (loss) in operating affiliates	55,810		76,786
Investee summarized data - total assets	15,417,241	[1]	13,854,966	[1]
Investee summarized data - total liabilities	14,229,060	[1]	12,937,275	[1]
Investee summarized data - total revenue (loss)	1,083,683	[1]	681,379	[1]
Investee summarized data - net income (loss)	332,197	[1]	272,016	[1]
Financial operating affiliates
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investment, operating affiliates	732		732
Equity in net income (loss) in operating affiliates	0		(1,018)
Investee summarized data - total assets	12,711,762	[1]	11,957,534	[1]
Investee summarized data - total liabilities	12,678,810	[1]	11,931,662	[1]
Investee summarized data - total revenue (loss)	20,467	[1]	12,564	[1]
Investee summarized data - net income (loss)	6,183	[1]	1,115	[1]
Other strategic operating affiliates
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investment, operating affiliates	192,792		153,955
Equity in net income (loss) in operating affiliates	27,033		20,891
Investee summarized data - total assets	2,094,539	[1]	1,295,921	[1]
Investee summarized data - total liabilities	1,512,551	[1]	967,264	[1]
Investee summarized data - total revenue (loss)	698,665	[1]	348,831	[1]
Investee summarized data - net income (loss)	51,702	[1]	48,641	[1]
Investment manager affiliates
Schedule of Equity Method Investments [Line Items]
Carrying value of equity method investment, operating affiliates	88,154		129,191	[2]
Equity in net income (loss) in operating affiliates	28,777		56,913	[2]
Investee summarized data - total assets	610,940	[1]	601,511	[1],[2]
Investee summarized data - total liabilities	37,699	[1]	38,349	[1],[2]
Investee summarized data - total revenue (loss)	364,551	[1]	319,984	[1],[2]
Investee summarized data - net income (loss)	$ 274,312	[1]	$ 222,260	[1],[2]

[1] The Company generally records its operating affiliates on a three month lag. Estimated assets and liabilities are generally at September 30, 2012 and 2011.

[2] During the year ended December 31, 2012 and 2011 the Company received distributions from its Investments Manager Affiliates of approximately $58.3 million and $23.2 million respectively. During 2011 the Company sold its interests in Finisterre for total proceeds of $35 million as explained below at "Investment Manager Affiliate".