Investments (Details 4) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Realized capital gains and losses by asset type
Realized capital gains and losses	$ 58	$ 7	$ 77	$ (15)
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains and losses	24	(6)	6	(56)
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains and losses	(6)	9	25	8
Equity securities
Realized capital gains and losses by asset type
Realized capital gains and losses	31		32
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains and losses	(3)	2	(3)	1
Derivatives
Realized capital gains and losses by asset type
Realized capital gains and losses	12	4	19	26
Other
Realized capital gains and losses by asset type
Realized capital gains and losses		$ (2)	$ (2)	$ 6