Reinsurance - Summary of the Impact of Funds Withheld (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Effects of Reinsurance [Line Items]
Total net investment income									$ 4,255	$ 3,446	$ 2,370
Net realized gains (losses)									(548)	(1,078)	827
Income (loss) from continuing operations before income tax expense (benefit)									3,870	2,867	3,772
Income tax expense (benefit)									1,170	126	882
Net income (loss)	$ 901	$ 457	$ (3,884)	$ 1,600	$ (473)	$ 2,747	$ 1,691	$ (87)	(926)	3,878	11,273
Change in unrealized appreciation (depreciation) on available for sale securities									571	(1,075)	(2,123)
Comprehensive income (loss)									5,179	9,818	(21,030)
Fortitude Re funds withheld assets
Effects of Reinsurance [Line Items]
Total net investment income									144	180	53
Fortitude Holdings
Effects of Reinsurance [Line Items]
Total net investment income									144	180	53
Net realized gains (losses)									(114)	(344)	1,034
Income (loss) from continuing operations before income tax expense (benefit)									30	(164)	1,087
Income tax expense (benefit)									6	(34)	228
Net income (loss)									24	(130)	859
Comprehensive income (loss)									(4)	(38)	11
Fortitude Holdings | Fortitude Re funds withheld assets
Effects of Reinsurance [Line Items]
Net realized gains (losses)									(39)	(71)	(99)
Fortitude Holdings | Fortitude Re funds withheld assets | Embedded derivatives
Effects of Reinsurance [Line Items]
Net realized gains (losses)									(75)	(273)	1,133
Fortitude Holdings | Other investments
Effects of Reinsurance [Line Items]
Change in unrealized appreciation (depreciation) on available for sale securities									$ (28)	$ 92	$ (848)