Accumulated Other Comprehensive Income (Loss) - Components of AOCI (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Debt Securities, Available-for-sale [Line Items]
Fixed maturities, net of OTTI	$ 1,715		$ 427
Derivatives(1)	137		119
DAC/VOBA and Sales inducements adjustment on available-for-sale securities	(458)		(146)
Premium deficiency reserve adjustment	(118)		(61)
Unrealized capital gains (losses), before tax	1,276		339
Deferred income tax asset (liability)	(139)		(83)
Unrealized capital gains (losses), after tax	1,137		256
Pension and other postretirement benefits liability, net of tax	3		4
AOCI	1,140	$ 108	$ 260
Other Contract
Debt Securities, Available-for-sale [Line Items]
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent	$ 23