Investments of Operating Entities and Consolidated Funds - Equity Method Investments - (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Other investments		$ 140,647	$ 167,464
Other than Temporary Impairment Losses, Investments	$ 800
Net Gains (Losses) on Securities, Derivatives and Other Investments
Schedule of Equity Method Investments [Line Items]
Income (Loss) from Equity Method Investments		(3,300)	49,100	$ 16,100
Clawback Obligation
Schedule of Equity Method Investments [Line Items]
Other Commitment		6,200	6,200
Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		27,067	61,443
Equity Method Investee, Exceeded Threshold for Income Test
Schedule of Equity Method Investments [Line Items]
Revenues		49,669	160,224	78,222
Expenses		(30,516)	(46,575)	(49,340)
Net realized and unrealized gains (losses)		13,221	14,325	18,589
Net Income		32,374	127,974	47,471
Equity		97,486	175,407
Assets		118,835	196,710
Liabilities		21,349	21,303
RCG Longview Debt Fund IV Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		331	676
RCG Longview Debt Fund V Partners, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		4,655	2,684
Healthcare Royalty GP, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		989	973
Healthcare Royalty GP II, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		1,017	1,125
Healthcare Royalty GP III, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		88	62
CBOE Stock Exchange, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		0	611
Starboard Value LP | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Realized Gain (Loss) on Disposal		14,400
Other investments		15,769	48,772
Notes Receivable, Related Parties		$ 9,600
Effective interest rate		5.00%
RCG Longview Partners, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		$ 0	237
RCG Longview Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		656	1,117
RCG Urban American, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		120	422
RCG Urban American Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		379	379
RCG Longview Equity Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		114	316
Urban American Real Estate Fund II, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		1,211	2,329
RCG Kennedy House, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		304	509
Equity Method Investee, Other | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments		1,434	1,231
RCG Longview Partners II, LLC | Clawback Obligation
Schedule of Equity Method Investments [Line Items]
Other Commitment		$ 6,200	6,200
Minimum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		20.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		55.00%
Operating Entities | Equity Method Investee, Exceeded Threshold for Income Test
Schedule of Equity Method Investments [Line Items]
Revenues		$ 36,641	129,203	41,879
Expenses		(20,658)	(20,362)	(11,602)
Net realized and unrealized gains (losses)		4,258	4,563	1,566
Net Income		20,241	113,404	$ 31,843
Cash		1,060	4,595
Performance & management fee receivable		32,638	108,355
Investments in Portfolio Funds, at fair value		18,797	12,403
Other assets		2,327	1,485
Liabilities		10,426	12,632
Equity		$ 44,396	$ 114,206