Fair Value Measurements for Operating Entities and Consolidated Funds - Unobservable Input Roll Forward (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021		Dec. 31, 2020
Corporate Bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Liability Value				$ 0		$ 704
Liability, Transfers In				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3				0
Liability, Purchases				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales				(399)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings				(305)
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	[1]			0
Options (held short)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Liability Value		$ 720		3,419		3,915
Liability, Transfers In		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0
Liability, Purchases		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		(2,699)		(496)
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	[1]	(2,699)		(496)
Government Debt Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Liability Value				0		1,500
Liability, Transfers In				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3				0
Liability, Purchases				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales				(1,569)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings				69
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	[1]			0
Contingent liability payable
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Liability Value		38,648		62,223		36,718
Liability, Transfers In		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0
Liability, Purchases		0		20,729
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales		(29,169)		(10,077)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		5,594		14,853
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)	[1]	5,594		14,853
Equity Swap
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Liability Value		879		0
Liability, Transfers In		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0
Liability, Purchases		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		879
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss)		879
Preferred Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		193,304		125,458		59,967
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		(1,531)	[2]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		26,164		78,389
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(1,347)		(9,828)
Realized and unrealized gains (losses), asset		43,029		(1,539)
Change in Unrealized Gain (Loss), instruments still held, asset	[1]	43,029		(2,570)
Common Stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		24,827		29,831		23,786
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		893	[3]	3,409	[4]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		(7,357)	[2],[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		5,031		16,245
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(950)		(13,582)
Realized and unrealized gains (losses), asset		(9,978)		7,330
Change in Unrealized Gain (Loss), instruments still held, asset	[1]	(13,736)		5,517
Common Stock | Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value				0		2,951
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3	[4]			(4,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				0
Realized and unrealized gains (losses), asset				1,049
Change in Unrealized Gain (Loss), instruments still held, asset	[1]			0
Convertible Bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		11,968		5,250		6,040
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		(4,031)	[5]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		6,636		11,802
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0		(11,159)
Realized and unrealized gains (losses), asset		82		2,598
Change in Unrealized Gain (Loss), instruments still held, asset	[1]	0		(975)
Corporate Bonds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		3,409		2,419		135
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		1,082	[3]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		620		2,414
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(460)		(103)
Realized and unrealized gains (losses), asset		(252)		(27)
Change in Unrealized Gain (Loss), instruments still held, asset	[1]	64		6
Options (held long)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		143		234		251
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0		0
Realized and unrealized gains (losses), asset		(91)		(17)
Change in Unrealized Gain (Loss), instruments still held, asset	[1]	(90)		(17)
Term Loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		9,966		0		12,623
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		9,700		638
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0		(12,162)
Realized and unrealized gains (losses), asset		266		(1,099)
Change in Unrealized Gain (Loss), instruments still held, asset		267	[1]	0
Warrants and Rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		26,937		15,403		6,547
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		3,806	[3],[4]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(719)	[2],[3]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		2,274		10,706
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(1,212)		(1,610)
Realized and unrealized gains (losses), asset		11,191		(4,046)
Change in Unrealized Gain (Loss), instruments still held, asset	[1]	14,614		(2,812)
Warrants and Rights | Consolidated Funds
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value				0		5,806
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases				0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				(4,447)
Realized and unrealized gains (losses), asset				(1,359)
Change in Unrealized Gain (Loss), instruments still held, asset	[1]			0
Trade Claims
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		5,440		2,988		8,713
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		(2,145)	[3]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		4,304		3,056
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(647)		(4,946)
Realized and unrealized gains (losses), asset		(1,205)		(1,690)
Change in Unrealized Gain (Loss), instruments still held, asset	[1]	(1,561)		(2,757)
Private Investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance Asset Value		1,138		704		$ 642
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		543	[3]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		8,311		707
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(8,978)		(1,462)
Realized and unrealized gains (losses), asset		1,101		274
Change in Unrealized Gain (Loss), instruments still held, asset		$ 405		$ 0

[1] Unrealized gains/losses are reported in Investment income - Securities principal transactions, net in the accompanying consolidated statements of operations

[2] The entity in which the Company is invested completed an initial public offering

[3] The transfers between level 1, level 2 and level 3 are due to the change in the availability of observable inputs.

[4] Fair market value derived using models and private transactions.

[5] The Company deconsolidated an investment fund.