Investments (Components of Net Investment Gains (Losses)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Net investment gains (losses), fixed maturity securities	$ 16	$ (34)	$ 63	$ (137)
Net investment gains (losses), equity securities	3	(2)	14	(5)
Net investment gains (losses), mortgage loans	(1)	(5)	(8)	(12)
Net investment gains (losses), real estate limited partnerships and limited liability companies	0	0	0	42
Net investment gains (losses), other limited partnership interests	(3)	0	(8)	0
Net investment gains (losses), other	(1)	(1)	(1)	(8)
Total net investment gains (losses)	$ 14	$ (42)	$ 60	$ (120)