Reinsurance - Summary of the Impact of Funds Withheld (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Effects of Reinsurance [Line Items]
Total net investment income	$ 973	$ 856	$ 2,942	$ 2,537
Net realized gains (losses)	(167)	(135)	(434)	(660)
Income (loss) from continuing operations before income tax expense (benefit)	649	1,100	2,324	2,388
Income tax expense (benefit)	168	399	571	509
Net income (loss)	457	2,747	(1,827)	4,351
Change in unrealized appreciation (depreciation) of all other investments			4	(564)
Comprehensive income (loss)	2,304	(2,171)	5,657	1,608
Fortitude Re funds withheld assets
Effects of Reinsurance [Line Items]
Total net investment income	51	29	123	106
Fortitude Holdings
Effects of Reinsurance [Line Items]
Total net investment income	51	29	123	106
Net realized gains (losses)	(175)	54	(196)	(89)
Income (loss) from continuing operations before income tax expense (benefit)	(124)	83	(73)	17
Income tax expense (benefit)	(26)	18	(15)	4
Net income (loss)	(98)	65	(58)	13
Comprehensive income (loss)	(31)	2	(33)	(34)
Fortitude Holdings | Fortitude Re funds withheld assets
Effects of Reinsurance [Line Items]
Net realized gains (losses)	(18)	(3)	(38)	(64)
Fortitude Holdings | Fortitude Re funds withheld assets | Embedded derivatives
Effects of Reinsurance [Line Items]
Net realized gains (losses)	(157)	57	(158)	(25)
Fortitude Holdings | Other investments
Effects of Reinsurance [Line Items]
Change in unrealized appreciation (depreciation) of all other investments	$ 67	$ (63)	$ 25	$ (47)