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
		Mar. 31, 2019	Mar. 31, 2018
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		$ 186	$ (92)
Realized — impairments		(2)	(1)
Total realized gains (losses) on securities		184	(93)
Net of tax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		147	(72)
Realized — impairments		(2)	(1)
Total realized gains (losses) on securities		145	(73)
Change in unrealized		381	(277)
Total pretax
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		186	(92)
Realized — impairments		(2)	(1)
Total realized gains (losses) on securities		184	(93)
Change in unrealized		483	(351)
Fixed maturities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		3	(1)
Realized — impairments		(3)	(1)
Total realized gains (losses) on securities		0	(2)
Change in unrealized		853	(599)
Equity securities
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		182	(95)
Realized — impairments		0	0
Total realized gains (losses) on securities		182	(95)
Change in unrealized		0	0
Other, Including DPAC and reserves related to the annuity business
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	[1]	1	4
Realized — impairments	[1]	1	0
Total realized gains (losses) on securities	[1]	2	4
Change in unrealized	[1]	(370)	248
Tax effects
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments		(39)	20
Realized — impairments		0	0
Total realized gains (losses) on securities		(39)	20
Change in unrealized		$ (102)	$ 74

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