Investments - Components of Net Realized Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Components of net realized capital gains (losses)
Sales of fixed maturity securities	$ (130)	$ (262)
Net realized gains (losses)	(135)	(103)
Excluding Fortitude Re Funds Withheld Assets
Components of net realized capital gains (losses)
Net realized gains (losses)	(132)	(60)
Fortitude Re Funds Withheld Assets
Components of net realized capital gains (losses)
Net realized gains (losses)	(3)	(43)
Excluding modified coinsurance and funds withheld embedded derivative
Components of net realized capital gains (losses)
Sales of fixed maturity securities	(130)	(262)
Change in allowance for credit losses on fixed maturity securities	(1)	8
Foreign exchange transactions	(22)	226
All other derivatives and hedge accounting	6	(34)
Sales of alternative investments	22	0
Other	(54)	(9)
Net realized gains (losses)	(145)	(62)
Excluding modified coinsurance and funds withheld embedded derivative | Loans Receivable
Components of net realized capital gains (losses)
Change in allowance for credit losses on loans	34	9
Excluding modified coinsurance and funds withheld embedded derivative | Excluding Fortitude Re Funds Withheld Assets
Components of net realized capital gains (losses)
Sales of fixed maturity securities	(115)	(255)
Change in allowance for credit losses on fixed maturity securities	(2)	8
Foreign exchange transactions	(19)	220
All other derivatives and hedge accounting	2	(28)
Sales of alternative investments	22	0
Other	(53)	(10)
Net realized gains (losses)	(132)	(60)
Excluding modified coinsurance and funds withheld embedded derivative | Excluding Fortitude Re Funds Withheld Assets | Loans Receivable
Components of net realized capital gains (losses)
Change in allowance for credit losses on loans	33	5
Excluding modified coinsurance and funds withheld embedded derivative | Fortitude Re Funds Withheld Assets
Components of net realized capital gains (losses)
Sales of fixed maturity securities	(15)	(7)
Change in allowance for credit losses on fixed maturity securities	1	0
Foreign exchange transactions	(3)	6
All other derivatives and hedge accounting	4	(6)
Sales of alternative investments	0	0
Other	(1)	1
Net realized gains (losses)	(13)	(2)
Excluding modified coinsurance and funds withheld embedded derivative | Fortitude Re Funds Withheld Assets | Loans Receivable
Components of net realized capital gains (losses)
Change in allowance for credit losses on loans	1	4
Fortitude Re funds withheld embedded derivative
Components of net realized capital gains (losses)
Net realized gains (losses)	10	(41)
Fortitude Re funds withheld embedded derivative | Excluding Fortitude Re Funds Withheld Assets
Components of net realized capital gains (losses)
Net realized gains (losses)	0	0
Fortitude Re funds withheld embedded derivative | Fortitude Re Funds Withheld Assets
Components of net realized capital gains (losses)
Net realized gains (losses)	$ 10	$ (41)