Investments - Realized Capital Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ 25	$ 48	$ 219	$ 24
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	19	(8)	17	(26)
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains (losses)	0	0	0	2
Equity securities
Realized capital gains and losses by asset type
Realized capital gains (losses)	7	56	192	50
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains (losses)	(2)	(4)	8	(12)
Derivatives
Realized capital gains and losses by asset type
Realized capital gains (losses)	8	4	16	11
Other
Realized capital gains and losses by asset type
Realized capital gains (losses)	$ (7)	$ 0	$ (14)	$ (1)