Derivative Instruments - Notional Value, Fair Value and Gains and Losses Recognized in Investment Gains (Losses) (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Derivative [Line Items]
Notional Value	$ 669,469	$ 446,989
Derivatives	20,941	14,518
Derivatives	14,944	18,180
Gains (Losses)	(7,930)	(16,410)
Exchange-traded futures
Derivative [Line Items]
Notional Value	157,787	116,344
Derivatives	2,835	1
Derivatives	33	3,511
Gains (Losses)	(2,744)	(2,038)
Currency forwards
Derivative [Line Items]
Notional Value	27,368	34,440
Derivatives	4,881	4,951
Derivatives	4,656	5,597
Gains (Losses)	1,690	(82)
Interest rate swaps
Derivative [Line Items]
Notional Value	17,667	11,345
Derivatives	367	294
Derivatives	14	349
Gains (Losses)	310	110
Credit default swaps
Derivative [Line Items]
Notional Value	199,720	139,607
Derivatives	4,172	9,265
Derivatives	9,099	4,197
Gains (Losses)	(2,675)	(6,850)
Total return swaps
Derivative [Line Items]
Notional Value	216,468	95,021
Derivatives	663	6
Derivatives	1,087	4,391
Gains (Losses)	(3,823)	(5,443)
Option swaps
Derivative [Line Items]
Notional Value	50,459	50,232
Derivatives	8,023	1
Derivatives	55	135
Gains (Losses)	$ (688)	$ (2,107)