Investments of Operating Entities and Consolidated Funds - Equity Method Investments - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Other investments	$ 167,450		$ 167,450		$ 140,647
Net Gains (Losses) on Securities, Derivatives and Other Investments
Schedule of Equity Method Investments [Line Items]
Income (Loss) from Equity Method Investments	(100)	$ (5,900)	16,000	$ 3,400
Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	51,485		51,485		27,067
Equity Method Investee, Exceeded Threshold for Income Test [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Summarized Financial Information, Revenue	9,005	(8,686)	9,747	(5,182)
Equity Method Investment, Summarized Financial Information, Expenses	0	0	0	0
Equity Method Investment, Summarized Financial Information, Gain (Loss) on Investments	37	(132)	92	(67)
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	9,042	$ (8,818)	9,839	$ (5,249)
RCG Longview Debt Fund IV Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	331		331		331
RCG Longview Debt Fund V Partners, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	6,594		6,594		4,655
Healthcare Royalty GP, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	739		739		989
Healthcare Royalty GP II, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	827		827		1,017
Healthcare Royalty GP III, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	197		197		88
Healthcare Overflow Fund GP, LLC [Member] | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	101		101		0
Surf House Ocean Views Holdings, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	13,383		13,383		0
Starboard Value LP | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	25,529		25,529		15,769
RCG Longview Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	714		714		656
RCG Urban American, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	107		107		120
RCG Urban American Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	379		379		379
RCG Longview Equity Management, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	114		114		114
Urban American Real Estate Fund II, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	1,311		1,311		1,211
RCG Kennedy House, LLC | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	227		227		304
Equity Method Investee, Other | Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Other investments	$ 932		$ 932		1,434
Minimum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	20.00%		20.00%
Maximum
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	55.00%		55.00%
Clawback Obligation [Member]
Schedule of Equity Method Investments [Line Items]
Other Commitment	$ 6,200		$ 6,200		6,200
Clawback Obligation [Member] | RCG Longview Partners II, LLC
Schedule of Equity Method Investments [Line Items]
Other Commitment	$ 6,200		$ 6,200		$ 6,200