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, 2023	Dec. 31, 2022	Dec. 31, 2021
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities	$ (36)	$ (116)	$ 110
Net of tax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(20)	(90)	86
Realized - impairments	(8)	(2)	1
Realized gains (losses) on securities	(28)	(92)	87
Change in unrealized	210	(633)	(88)
Total pretax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(25)	(113)	109
Realized - impairments	(11)	(3)	1
Realized gains (losses) on securities	(36)	(116)	110
Change in unrealized	267	(803)	(111)
Fixed maturities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(35)	(27)	(1)
Realized - impairments	(10)	(3)	1
Realized gains (losses) on securities	(45)	(30)	0
Change in unrealized	267	(803)	(111)
Equity securities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	10	(96)	110
Realized - impairments	0	0	0
Realized gains (losses) on securities	10	(96)	110
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 before impairments	0	10	0
Realized - impairments	(1)	0	0
Realized gains (losses) on securities	(1)	10	0
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 before impairments	5	23	(23)
Realized - impairments	3	1	0
Realized gains (losses) on securities	8	24	(23)
Change in unrealized	$ (57)	$ 170	$ 23