Market Risk Benefits - Rollforward of Balances for Variable Annuity Products (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 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	830,031	878,381
Claims paid	(45,249)	(62,128)
Interest accrual	171,713	235,979
Actual in force different from expected	18,607	52,753
Effect of changes in interest rates	44,706	(2,869,989)
Effect of changes in equity markets	(1,633,684)	(940,654)
Effect of assumption update	85,619	330,769
Issuances	51,540	21,271
Other adjustments	14,958	(17,436)
Effect of changes in current period counterparty non-performance risk	0	0
Balance, end of period, before effect of changes in non-performance risk	4,301,226	3,907,481
Effect of cumulative changes in non-performance risk	(934,425)	(1,230,621)
Balance, end of period	3,366,801	2,676,860
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	(42,483)	(38,016)
Actual in force different from expected	(14,423)	(6,588)
Effect of changes in interest rates	51,322	484,168
Effect of changes in equity markets	171,342	90,742
Effect of assumption update	3,984	(54,067)
Other adjustments	27	(638,198)
Effect of changes in current period counterparty non-performance risk	(8,520)	(75,594)
Balance, end of period, before effect of changes in non-performance risk	(950,872)	(824,916)
Effect of cumulative changes in non-performance risk	0	0
Balance, end of period	(950,872)	(824,916)
Less: Reinsured Market Risk Benefits | AuguStar [Member]
Market Risk Benefit [Roll Forward]
Other adjustments	638,000
Less: Reinsured Market Risk Benefits
Market Risk Benefit [Roll Forward]
Attributed fees collected	(195,952)	(179,211)
Claims paid	4,781	5,903
Issuances	(3,158)	8,206
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	634,079	699,170
Claims paid	(40,468)	(56,225)
Interest accrual	129,230	197,963
Actual in force different from expected	4,184	46,165
Effect of changes in interest rates	96,028	(2,385,821)
Effect of changes in equity markets	(1,462,342)	(849,912)
Effect of assumption update	89,603	276,702
Issuances	48,382	29,477
Other adjustments	14,985	(655,634)
Effect of changes in current period counterparty non-performance risk	(8,520)	(75,594)
Balance, end of period, before effect of changes in non-performance risk	3,350,354	3,082,565
Effect of cumulative changes in non-performance risk	(934,425)	(1,230,621)
Balance, end of period	$ 2,415,929	$ 1,851,944