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	$ 362	$ 27	$ 493	$ 195
Fixed income securities
Realized capital gains and losses by asset type
Realized capital gains and losses	79	6	151	(23)
Equity securities
Realized capital gains and losses by asset type
Realized capital gains and losses	283	13	312	172
Mortgage loans
Realized capital gains and losses by asset type
Realized capital gains and losses	(6)	9	25	8
Limited partnership interests
Realized capital gains and losses by asset type
Realized capital gains and losses	(8)	3	(3)	13
Derivatives
Realized capital gains and losses by asset type
Realized capital gains and losses	14	7	10	28
Other
Realized capital gains and losses by asset type
Realized capital gains and losses		$ (11)	$ (2)	$ (3)