Investments - Realized Capital Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 148	$ (32)
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains and losses	(6)	(6)
Equity securities
Realized capital gains and losses by asset type
Realized capital gains and losses	146	(26)
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains and losses	10	3
Derivatives
Realized capital gains and losses by asset type
Realized capital gains and losses	4	(3)
Other
Realized capital gains and losses by asset type
Realized capital gains and losses	$ (6)	$ 0