Equity Method Investments and Other - Schedule of Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Schedule of Equity Method Investments [Line Items]
Net investment income	$ 27,055	$ 19,422
Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(1,297)	(1,988)
RISCOM \| Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	719	(128)
Dowling Capital Partners LP units \| Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	175	13
Hudson Ventures Fund II LP units \| Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(106)	(25)
Brewer Lane Ventures Fund II LP \| Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(12)	170
JVM Funds LLC \| Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	(431)	(211)
Arena SOP LP units \| Equity Method Investment, Nonconsolidated Investee or Group of Investees
Schedule of Equity Method Investments [Line Items]
Net investment income	0	(1,256)
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	$ (1,642)	$ (551)