Investments (Components of Net Investment Gains (Losses)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Net investment gains (losses), fixed maturity securities	$ 297	$ 106	$ (180)
Net investment gains (losses), equity securities	0	17	(16)
Net investment gains (losses), mortgage loans	(27)	(10)	(13)
Net investment gains (losses), limited partnerships and LLCs	(3)	7	40
Net investment gains (losses), other	11	(8)	(38)
Net investment gains (losses)	$ 278	$ 112	$ (207)