Investments Of Operating Entities And Consolidated Funds - Operating Entities - Receivable On And Payable For Derivative Contracts, At Fair Value (Details)		Sep. 30, 2021 USD ($) contract	Dec. 31, 2020 USD ($) contract
Derivative [Line Items]
Receivable on derivative contracts, at fair value		$ 212,421,000	$ 51,482,000
Payable for derivative contracts, at fair value		46,872,000	76,160,000
Receivable on derivatives contracts, at fair value [Member]
Derivative [Line Items]
Receivable on derivative contracts, at fair value		212,421,000	51,482,000
Derivative Asset, Fair Value, Amount Offset Against Collateral	[1],[2]	(154,015,000)	(62,269,000)
Payable for derivatives contracts, at fair value [Member]
Derivative [Line Items]
Payable for derivative contracts, at fair value		46,872,000	76,160,000
Derivative Liability, Fair Value, Amount Offset Against Collateral	[1],[2]	(141,280,000)	(37,033,000)
Futures
Derivative [Line Items]
Derivative Liability, Notional Amount		13,164,000	0
Payable for derivative contracts, at fair value		261,000	0
Currency Forwards
Derivative [Line Items]
Derivative Asset, Notional Amount		141,105,000	4,902,000
Receivable on derivative contracts, at fair value		1,241,000	15,000
Derivative Liability, Notional Amount		5,180,000	123,346,000
Payable for derivative contracts, at fair value		22,000	3,067,000
Equity Swaps
Derivative [Line Items]
Derivative Asset, Notional Amount		3,128,378,000	944,544,000
Receivable on derivative contracts, at fair value		320,825,000	64,634,000
Derivative Liability, Notional Amount		886,267,000	896,863,000
Payable for derivative contracts, at fair value		$ 146,837,000	$ 43,560,000
Options (held long)
Derivative [Line Items]
Derivative Asset, Number of Instruments Held | contract	[3]	186,836	371,188
Receivable on derivative contracts, at fair value	[3]	$ 44,370,000	$ 49,102,000
Interest rate swap
Derivative [Line Items]
Derivative Liability, Notional Amount		285,000,000	0
Payable for derivative contracts, at fair value		$ 518,000	$ 0
Options (held short)
Derivative [Line Items]
Derivative Liability, Number of Instruments Held | contract	[3]	163,652	198,320
Payable for derivative contracts, at fair value	[3]	$ 40,514,000	$ 66,566,000

[1] Derivatives are reported on a net basis, by counterparty, when a legal right of offset exists under an enforceable netting agreement as well as net of cash collateral received or posted under enforceable credit support agreements. See Note 2f for further information on offsetting of derivative financial instruments.

[2] Includes financial instruments subject to enforceable master netting provisions that are permitted to be offset to the extent an event of default has occurred

[3] Includes the volume of contracts for index, equity, commodity future and cash conversion options.