Investments- Realized Capital Gains and Losses (Details 4) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Realized capital gains and losses by asset type
Realized capital gains and losses	$ (1)	$ (46)
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains and losses	(7)	(23)
Equity securities
Realized capital gains and losses by asset type
Realized capital gains and losses	0	(30)
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains and losses	13	13
Derivatives
Realized capital gains and losses by asset type
Realized capital gains and losses	(5)	(5)
Other
Realized capital gains and losses by asset type
Realized capital gains and losses	$ (2)	$ (1)