Investments - Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities	$ (93)	$ 43	$ (108)	$ 120
Net of tax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(72)	34	(86)	94
Realized — impairments	(1)	0	1	1
Realized gains (losses) on securities	(73)	34	(85)	95
Change in unrealized	(217)	16	(462)	(19)
Total pretax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(92)	43	(109)	119
Realized — impairments	(1)	0	1	1
Realized gains (losses) on securities	(93)	43	(108)	120
Change in unrealized	(275)	20	(586)	(24)
Fixed maturities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(10)	1	(14)	0
Realized — impairments	(1)	0	1	1
Realized gains (losses) on securities	(11)	1	(13)	1
Change in unrealized	(275)	20	(586)	(24)
Equity securities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(82)	42	(95)	119
Realized — impairments	0	0	0	0
Realized gains (losses) on securities	(82)	42	(95)	119
Change in unrealized	0	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	0	0	0
Realized — impairments	0	0	0	0
Realized gains (losses) on securities	0	0	0	0
Change in unrealized	0	0	0	0
Tax effects
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	20	(9)	23	(25)
Realized — impairments	0	0	0	0
Realized gains (losses) on securities	20	(9)	23	(25)
Change in unrealized	$ 58	$ (4)	$ 124	$ 5