Investments (Net Unrealized Investment Gains (Losses)) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities	$ 6,030	$ 6,894
Derivatives	783	232
Other	(21)	(15)
Subtotal	6,792	7,111
Amounts allocated from: Future policy benefits	(3,425)	(2,691)
Amounts allocated from: DAC, VOBA and DSI	(247)	(332)
Subtotal	(3,672)	(3,023)
Deferred income tax benefit (expense)	(655)	(859)
Net unrealized investment gains (losses)	$ 2,465	$ 3,229