Investments (Net Unrealized Investment Gains (Losses)) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities	$ 6,957	$ 1,691	$ 4,808
Equity securities	0	0	39
Derivatives	245	264	239
Other	(13)	(13)	(8)
Subtotal	7,189	1,942	5,078
Amounts allocated from: Future policy benefits	(2,692)	(886)	(2,626)
Amounts allocated from: DAC, VOBA and DSI	(341)	(90)	(267)
Subtotal	(3,033)	(976)	(2,893)
Deferred income tax benefit (expense)	(873)	(203)	(459)
Net unrealized investment gains (losses)	$ 3,283	$ 763	$ 1,726