Derivative Instruments - Schedule of Gains and Losses for Derivative Instruments Recognized in Investment Gains (Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative [Line Items]
Net (losses) on derivative instruments	$ (4,879)	$ (15,285)	$ (28,729)	$ (21,865)
Exchange-traded futures
Derivative [Line Items]
Net (losses) on derivative instruments	(3,782)	(5,443)	(7,415)	(7,893)
Currency forwards
Derivative [Line Items]
Net (losses) on derivative instruments	809	(460)	(4,966)	(105)
Interest rate swaps
Derivative [Line Items]
Net (losses) on derivative instruments	9	(1,298)	(301)	(873)
Credit default swaps
Derivative [Line Items]
Net (losses) on derivative instruments	(1,445)	(920)	(3,932)	(1,840)
Total return swaps
Derivative [Line Items]
Net (losses) on derivative instruments	168	(5,295)	(9,209)	(9,233)
Option swaps
Derivative [Line Items]
Net (losses) on derivative instruments	$ (638)	$ (1,869)	$ (2,906)	$ (1,921)