Investments of Operating Entities and Consolidated Funds - Operating Entities - Equity Method Investment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Net gains (losses) on other investments	$ 5,600	$ 12,600
Equity method investments	35,581		$ 47,200
Starboard Value LP
Schedule of Equity Method Investments [Line Items]
Equity method investments	25,741		36,889
Healthcare Royalty GP III, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	1,830		1,957
Healthcare Royalty GP, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	1,595		1,451
Healthcare Royalty GP II, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	210		213
Healthcare Royalty GP IV, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	1,618		1,716
RCG Longview Debt Fund IV Management, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	331		331
HCR Overflow Fund GP, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	774		839
HCRP MGS Account Management, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	114		598
HCR Stafford Fund GP, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	3,119		2,955
Other
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 249		$ 251