Investments (Net Unrealized Investment Gains Losses) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities	$ 1,540	$ 4,722
Fixed maturity securities with noncredit OTTI losses included in AOCI	5	2
Total fixed maturity securities	1,545	4,724
Equity securities	0	39
Derivatives	194	231
Other	(14)	(8)
Subtotal	1,725	4,986
Future policy benefits	(849)	(2,370)
DAC and VOBA related to noncredit OTTI losses recognized in AOCI	(4)	(2)
DAC, VOBA and DSI	(131)	(260)
Subtotal	(984)	(2,632)
Net Unrealized Investment Gains Losses Included In Accumulated Other Comprehensive Income Loss Related To Deferred Income Tax Benefit Expense On Which Non Credit Otti Losses Have Been Recognized	2	1
Deferred income tax benefit (expense)	(158)	(495)
Net unrealized investment gains (losses)	$ 585	$ 1,860