Derivative Instruments - Summary of Gains and Losses for Derivative Instruments Recognized in Investment Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Derivative [Line Items]
Net gains (losses) on derivative instruments	$ 11,145	$ (4,879)	$ 1,425	$ (28,729)
Exchange-traded futures
Derivative [Line Items]
Net gains (losses) on derivative instruments	7,562	(3,782)	1,313	(7,415)
Currency forwards
Derivative [Line Items]
Net gains (losses) on derivative instruments	1,315	809	4,942	(4,966)
Interest rate swaps
Derivative [Line Items]
Net gains (losses) on derivative instruments	526	9	12	(301)
Credit default swaps
Derivative [Line Items]
Net gains (losses) on derivative instruments	254	(1,445)	(1,740)	(3,932)
Total return swaps
Derivative [Line Items]
Net gains (losses) on derivative instruments	590	168	(5,625)	(9,209)
Option swaps
Derivative [Line Items]
Net gains (losses) on derivative instruments	$ 898	$ (638)	$ 2,523	$ (2,906)