Investments (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 143	$ 76	$ (16)
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains and losses	(4)	3	(62)
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains and losses	2	20	8
Equity securities
Realized capital gains and losses by asset type
Realized capital gains and losses	134	45	0
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains and losses	(4)	(6)	0
Derivatives
Realized capital gains and losses by asset type
Realized capital gains and losses	12	14	34
Other
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 3	$ 0	$ 4