Market Risk Benefits - Rollforward of Balances for Variable Annuity Products (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Variable Annuities
Market Risk Benefit [Roll Forward]
Balance, beginning of period	$ 3,694,950	$ 4,550,625
Effect of cumulative changes in non-performance risk	1,068,035	1,727,910
Balance, beginning of period, before effect of changes in non-performance risk	4,762,985	6,278,535
Attributed fees collected	281,171	293,206
Claims paid	(16,417)	(23,881)
Interest accrual	68,360	78,947
Actual in force different from expected	2,495	19,425
Effect of changes in interest rates	(832,834)	438,057
Effect of changes in equity markets	(846,759)	(635,535)
Issuances	12,766
Effect of changes in current period counterparty non-performance risk	0	0
Other adjustments	13,017	77,790
Balance, end of period, before effect of changes in non-performance risk	3,444,784	6,526,544
Effect of cumulative changes in non-performance risk	(829,061)	(1,908,334)
Balance, end of period	2,615,723	4,618,210
Less: Reinsured Market Risk Benefits
Market Risk Benefit [Roll Forward]
Balance, beginning of period	(917,792)	(422,261)
Effect of cumulative changes in non-performance risk	0	0
Balance, beginning of period, before effect of changes in non-performance risk	(917,792)	(422,261)
Interest accrual	(15,642)	(2,290)
Actual in force different from expected	(4,539)	(2,389)
Effect of changes in interest rates	180,022	(49,031)
Effect of changes in equity markets	87,042	66,494
Effect of changes in current period counterparty non-performance risk	(26,662)	18,297
Other adjustments	(603)	0
Balance, end of period, before effect of changes in non-performance risk	(764,249)	(424,017)
Effect of cumulative changes in non-performance risk	0	0
Balance, end of period	(764,249)	(424,017)
Less: Reinsured Market Risk Benefits
Market Risk Benefit [Roll Forward]
Attributed fees collected	(66,967)	(34,490)
Claims paid	1,511	1,653
Issuances	(619)
Total, Net of Reinsurance
Market Risk Benefit [Roll Forward]
Balance, beginning of period	2,777,158	4,128,364
Effect of cumulative changes in non-performance risk	1,068,035	1,727,910
Balance, beginning of period, before effect of changes in non-performance risk	3,845,193	5,856,274
Attributed fees collected	214,204	258,716
Claims paid	(14,906)	(22,228)
Interest accrual	52,718	76,657
Actual in force different from expected	(2,044)	17,036
Effect of changes in interest rates	(652,812)	389,026
Effect of changes in equity markets	(759,717)	(569,041)
Issuances	12,147
Effect of changes in current period counterparty non-performance risk	(26,662)	18,297
Other adjustments	12,414	77,790
Balance, end of period, before effect of changes in non-performance risk	2,680,535	6,102,527
Effect of cumulative changes in non-performance risk	(829,061)	(1,908,334)
Balance, end of period	$ 1,851,474	$ 4,194,193