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	$ 6,894	$ 1,679	$ 4,724
Equity securities	0	0	39
Derivatives	232	253	231
Other	(15)	(15)	(8)
Subtotal	7,111	1,917	4,986
Amounts allocated from: Future policy benefits	(2,691)	(885)	(2,370)
Amounts allocated from: DAC, VOBA and DSI	(332)	(90)	(262)
Subtotal	(3,023)	(975)	(2,632)
Deferred income tax benefit (expense)	(859)	(198)	(494)
Net unrealized investment gains (losses)	$ 3,229	$ 744	$ 1,860