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, 2020	Dec. 31, 2019	Dec. 31, 2018
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized gains (losses) on securities	$ 289	$ 287	$ (266)
Net of tax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	256	242	(195)
Realized - impairments	(28)	(15)	(15)
Realized gains (losses) on securities	228	227	(210)
Change in unrealized	393	779	(536)
Total pretax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	324	306	(247)
Realized - impairments	(35)	(19)	(19)
Realized gains (losses) on securities	289	287	(266)
Change in unrealized	498	986	(679)
Fixed maturities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	468	26	6
Realized - impairments	(46)	(29)	(26)
Realized gains (losses) on securities	422	(3)	(20)
Change in unrealized	858	1,821	(1,181)
Equity securities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(96)	277	(265)
Realized - impairments	0	0	0
Realized gains (losses) on securities	(96)	277	(265)
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	4	3	1
Realized - impairments	0	0	0
Realized gains (losses) on securities	4	3	1
Change in unrealized	0	0	0
Other, Including DPAC and reserves related to annuity business
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(52)	0	11
Realized - impairments	11	10	7
Realized gains (losses) on securities	(41)	10	18
Change in unrealized	(360)	(835)	502
Total tax effects
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	(68)	(64)	52
Realized - impairments	7	4	4
Realized gains (losses) on securities	(61)	(60)	56
Change in unrealized	$ (105)	$ (207)	$ 143