Investments (Net realized 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
Fixed maturity securities:
Gross gains	$ 34	$ 42	$ 98	$ 148
Gross losses	(31)	(32)	(104)	(116)
Net investment gains (losses) on fixed maturity securities	3	10	(6)	32
Equity securities	7	2	60	(23)
Derivatives	(2)	1	(13)	10
Short term investments and other	(1)	1	(21)	6
Net investment gains	$ 7	$ 14	$ 20	$ 25