Investments of Operating Entities and Consolidated Funds - Operating Entities - Equity Method Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Net gains (losses) on other investments	$ 35,500	$ 18,900	$ 24,600
Equity method investments	47,200	38,681
Starboard Value LP
Schedule of Equity Method Investments [Line Items]
Equity method investments	36,889	31,528
Healthcare Royalty GP III, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	1,957	2,213
RCG Longview Management, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	0	268
Healthcare Royalty GP, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	1,451	920
Healthcare Royalty GP II, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	213	269
Healthcare Royalty GP IV, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	1,716	304
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	839	740
RCG Longview Equity Management, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	0	105
HCRP MGS Account Management, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	598	500
HCR Stafford Fund GP, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investments	2,955	1,025
Liberty Harbor North
Schedule of Equity Method Investments [Line Items]
Equity method investments	0	222
Equity Method Investee, Other
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 251	$ 256