Investments - Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities	$ 0	$ (36)	$ (116)
Net of tax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	21	(20)	(90)
Impairment allowance on securities	(21)	(8)	(2)
Realized gains (losses) on securities	0	(28)	(92)
Change in unrealized	85	210	(633)
Total pretax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	27	(25)	(113)
Impairment allowance on securities	(27)	(11)	(3)
Realized gains (losses) on securities	0	(36)	(116)
Change in unrealized	108	267	(803)
Fixed maturities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	(5)	(35)	(27)
Impairment allowance on fixed maturity securities	(27)	(10)	(3)
Realized gains (losses) on securities	(32)	(45)	(30)
Change in unrealized	108	267	(803)
Equity securities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	32	10	(96)
Realized gains (losses) on securities	32	10	(96)
Change in unrealized	0	0	0
Mortgage loans and other investments
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	0	0	10
Impairment allowance on mortgage loans and other investments	0	(1)	0
Realized gains (losses) on securities	0	(1)	10
Change in unrealized	0	0	0
Total tax effects
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities before impairments	(6)	5	23
Impairment allowance on securities	6	3	1
Realized gains (losses) on securities	0	8	24
Change in unrealized	$ (23)	$ (57)	$ 170