Other Long-Term Investments - Net Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Net investment income	$ 40,322	$ 36,931
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(9,434)	6,015
Arena SOP LP units | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(6,271)	3,042
Arena Special Opportunities Fund, LP units | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(2,880)	3,719
Dowling Capital Partners LP units | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	927	502
Hudson Ventures Fund 2 LP units | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	170	379
JVM Funds LLC units | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(1,198)	(70)
RISCOM | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	884	1,471
Brewer Lane Ventures Fund II LP units | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(78)	0
Universa Black Swan LP units | Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	$ (988)	$ (3,028)