Market Risk Benefits - Rollforward of Balances for Variable Annuity Products (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Variable Annuities
Market Risk Benefit [Roll Forward]
Balance, beginning of period	$ 2,488,463	$ 3,707,407
Effect of cumulative changes in non-performance risk	626,845	1,067,983
Balance, beginning of period, before effect of changes in non-performance risk	3,115,308	4,775,390
Attributed fees collected	259,010	281,171
Claims paid	(14,280)	(16,417)
Interest accrual	37,780	68,360
Actual in force different from expected	18,542	2,495
Effect of changes in interest rates	414,243	(832,834)
Effect of changes in equity markets	227,938	(846,759)
Issuances	23,528	12,766
Other adjustments	(294)	612
Effect of changes in current period counterparty non-performance risk	0	0
Balance, end of period, before effect of changes in non-performance risk	4,081,775	3,444,784
Effect of cumulative changes in non-performance risk	(788,058)	(829,061)
Balance, end of period	3,293,717	2,615,723
Less: Reinsured Market Risk Benefits
Market Risk Benefit [Roll Forward]
Balance, beginning of period	(844,582)	(917,792)
Effect of cumulative changes in non-performance risk	0	0
Balance, beginning of period, before effect of changes in non-performance risk	(844,582)	(917,792)
Interest accrual	(11,107)	(15,642)
Actual in force different from expected	(5,273)	(4,539)
Effect of changes in interest rates	(105,463)	180,022
Effect of changes in equity markets	(24,533)	87,042
Other adjustments	40	(603)
Effect of changes in current period counterparty non-performance risk	52,228	(26,662)
Balance, end of period, before effect of changes in non-performance risk	(999,400)	(764,249)
Effect of cumulative changes in non-performance risk	0	0
Balance, end of period	(999,400)	(764,249)
Less: Reinsured Market Risk Benefits
Market Risk Benefit [Roll Forward]
Attributed fees collected	(60,167)	(66,967)
Claims paid	1,634	1,511
Issuances	(2,177)	(619)
Total, Net of Reinsurance
Market Risk Benefit [Roll Forward]
Balance, beginning of period	1,643,881	2,789,615
Effect of cumulative changes in non-performance risk	626,845	1,067,983
Balance, beginning of period, before effect of changes in non-performance risk	2,270,726	3,857,598
Attributed fees collected	198,843	214,204
Claims paid	(12,646)	(14,906)
Interest accrual	26,673	52,718
Actual in force different from expected	13,269	(2,044)
Effect of changes in interest rates	308,780	(652,812)
Effect of changes in equity markets	203,405	(759,717)
Issuances	21,351	12,147
Other adjustments	(254)	9
Effect of changes in current period counterparty non-performance risk	52,228	(26,662)
Balance, end of period, before effect of changes in non-performance risk	3,082,375	2,680,535
Effect of cumulative changes in non-performance risk	(788,058)	(829,061)
Balance, end of period	$ 2,294,317	$ 1,851,474