Investments (Details 4) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 265	$ 143	$ 76
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains and losses	309	(4)	3
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains and losses	6	2	20
Equity securities
Realized capital gains and losses by asset type
Realized capital gains and losses	(23)	134	45
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains and losses	(32)	(4)	(6)
Derivatives
Realized capital gains and losses by asset type
Realized capital gains and losses	13	12	14
Other
Realized capital gains and losses by asset type
Realized capital gains and losses	$ (8)	$ 3	$ 0