Investments (Net Unrealized Investment Gains (Losses)) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities	$ 3,707	$ 1,679
Derivatives	193	253
Other	(13)	(15)
Subtotal	3,887	1,917
Future policy benefits	(1,564)	(885)
DAC, VOBA and DSI	(191)	(90)
Subtotal	(1,755)	(975)
Deferred income tax benefit (expense)	(448)	(198)
Net unrealized investment gains (losses)	$ 1,684	$ 744