Investments - Schedule of Changes in Assets Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Percent of total fixed maturities	100.00%		100.00%
Significant Unobservable Inputs (Level 3)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance	$ 474,114	$ 496,879
Included in realized gains / losses	(3,181)	0
Included in other comprehensive income	9,981	6,210
Acquisitions	82,421	22,676
Sales	(154,777)	0
Amortization	1,688	3,376
Other	(30,062)	(32,971)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending Balance	$ 380,184	$ 496,170
Percent of total fixed maturities	2.00%	3.00%	3.00%
Significant Unobservable Inputs (Level 3) | Asset- backed Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance	$ 11,183	$ 0
Included in realized gains / losses	0	0
Included in other comprehensive income	320	0
Acquisitions	52,406	7,876
Sales	0	0
Amortization	0	0
Other	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending Balance	$ 63,909	$ 7,876
Percent of total fixed maturities	0.00%	0.00%
Significant Unobservable Inputs (Level 3) | Collateralized debt obligations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance	$ 42,866	$ 42,146
Included in realized gains / losses	(588)	0
Included in other comprehensive income	0	762
Acquisitions	0	0
Sales	(36,398)	0
Amortization	1,893	3,414
Other	(7,773)	(3,839)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending Balance	$ 0	$ 42,483
Percent of total fixed maturities	0.00%	0.00%
Significant Unobservable Inputs (Level 3) | Corporates
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation
Beginning Balance	$ 420,065	$ 454,733
Included in realized gains / losses	(2,593)	0
Included in other comprehensive income	9,661	5,448
Acquisitions	30,015	14,800
Sales	(118,379)	0
Amortization	(205)	(38)
Other	(22,289)	(29,132)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Ending Balance	$ 316,275	$ 445,811
Percent of total fixed maturities	2.00%	3.00%