Investments in Affiliates - Operating Affiliates (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Investments in affiliates		$ 2,177,645	$ 1,708,899
Equity in net income (loss) in operating affiliates		115,155	118,060	$ 203,034
Operating affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates		502,720	322,062
Equity in net income (loss) in operating affiliates		44,397	44,740
Investee summarized data - total assets		6,106,241	4,989,581
Investee summarized data - total liabilities		3,863,414	3,389,699
Investee summarized data - total revenue (loss)		1,368,641	1,053,803
Investee summarized data - net income (loss)		287,428	182,192
Operating affiliates | Other strategic operating affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates		446,695	251,348
Equity in net income (loss) in operating affiliates		12,622	33,608
Investee summarized data - total assets		5,353,905	4,280,976
Investee summarized data - total liabilities		3,791,300	3,293,873
Investee summarized data - total revenue (loss)		1,030,859	847,131
Investee summarized data - net income (loss)		30,424	91,701
Operating affiliates | Investment manager affiliates
Schedule of Equity Method Investments [Line Items]
Investments in affiliates	[1]	56,025	70,714
Equity in net income (loss) in operating affiliates	[1]	31,775	11,132
Investee summarized data - total assets	[1]	752,336	708,605
Investee summarized data - total liabilities	[1]	72,114	95,826
Investee summarized data - total revenue (loss)	[1]	337,782	206,672
Investee summarized data - net income (loss)	[1]	$ 257,004	$ 90,491

[1] During the years ended December 31, 2016 and 2015, the Company received distributions from its Investment Manager Affiliates of approximately $35.9 million and $25.3 million, respectively.