Investments (Net Unrealized Investment Gains Losses) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities	$ 1,679	$ 4,724	$ 2,601
Equity securities	0	39	32
Derivatives	253	231	397
Short-term investments	0	0	(42)
Other	(15)	(8)	59
Subtotal	1,917	4,986	3,047
Future policy benefits	(885)	(2,370)	(922)
DAC, VOBA and DSI	(90)	(262)	(195)
Subtotal	(975)	(2,632)	(1,117)
Deferred income tax benefit (expense)	(198)	(494)	(653)
Net unrealized investment gains (losses)	$ 744	$ 1,860	$ 1,277