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, 2018	Dec. 31, 2017	Dec. 31, 2016
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		$ (247)	$ 78	$ 135
Realized - impairments		(19)	(73)	(116)
Total realized gains (losses) on securities		(266)	5	19
Net of tax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		(195)	51	85
Realized - impairments		(15)	(48)	(72)
Total realized gains (losses) on securities		(210)	3	13
Change in unrealized		(536)	436	72
Total pretax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		(247)	78	135
Realized - impairments		(19)	(73)	(116)
Total realized gains (losses) on securities		(266)	5	19
Change in unrealized		(679)	441	105
Fixed maturities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		6	17	36
Realized - impairments		(26)	(20)	(38)
Total realized gains (losses) on securities		(20)	(3)	(2)
Change in unrealized		(1,181)	532	90
Equity securities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		(265)	70	106
Realized - impairments		0	(64)	(93)
Total realized gains (losses) on securities		(265)	6	13
Change in unrealized		0	128	67
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		1	(6)
Realized - impairments		0	(4)
Total realized gains (losses) on securities		1	(10)
Change in unrealized		0	0
Other, Including DPAC and reserves on annuities and long-term care
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	[1]	11	(3)	(7)
Realized - impairments	[1]	7	15	15
Total realized gains (losses) on securities	[1]	18	12	8
Change in unrealized	[1]	502	(219)	(52)
Total tax effects
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		52	(27)	(48)
Realized - impairments		4	25	41
Total realized gains (losses) on securities		56	(2)	(7)
Change in unrealized		143	(5)	(37)
Effects Of Tax Cuts And Jobs Act Of 2017
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		0	0
Realized - impairments		0	0
Total realized gains (losses) on securities		0	0
Change in unrealized		0	149
Other tax effects
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		52	(27)
Realized - impairments		4	25
Total realized gains (losses) on securities		56	(2)
Change in unrealized		$ 143	$ (154)
Noncontrolling interests
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments				(2)
Realized - impairments				3
Total realized gains (losses) on securities				1
Change in unrealized				$ 4

[1] Primarily adjustments to deferred policy acquisition costs and reserves related to the annuity business.