Accumulated Other Comprehensive Income (Loss) - Components of AOCI (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components Of Accumulated Other Comprehensive Income Loss [Line Items]
Derivatives	$ 140	$ 124	$ 201
DAC/VOBA and Sales inducements adjustments on available-for-sale securities	(73)	(433)	(324)
Premium deficiency reserve adjustment	(51)	(115)	(90)
Other	0	5	0
Unrealized capital gains (losses), before tax	143	1,047	664
Deferred income tax asset (liability)	(39)	(234)	(111)
Unrealized capital gains (losses), after tax	104	813	553
Pension and other postretirement benefits liability, net of tax	4	5	6
AOCI	108	818	559
Fixed maturities
Components Of Accumulated Other Comprehensive Income Loss [Line Items]
Fixed maturities, net of OTTI	127	1,451	862
Equity securities
Components Of Accumulated Other Comprehensive Income Loss [Line Items]
Equity securities	$ 0	$ 15	$ 15