Investments (Net realized investment gains (losses)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Gain (Loss) on Investments
Net realized investment gains (losses), net of participating policyholders’ interests	$ 22		$ 15		$ 58		$ 28
Fixed maturity securities [Member]
Gain (Loss) on Investments
Available-for-sale Securities, Gross Realized Gains	49		89		118		177
Available-for-sale Securities, Gross Realized Losses	(32)		(69)		(71)		(137)
Net realized investment gains (losses), net of participating policyholders’ interests	17		20		47		40
Equity securities [Member]
Gain (Loss) on Investments
Available-for-sale Securities, Gross Realized Gains	2		1		5		6
Available-for-sale Securities, Gross Realized Losses	(2)		(3)		(4)		(8)
Net realized investment gains (losses), net of participating policyholders’ interests			(2)		1		(2)
Gain (Loss) on Derivatives [Member]
Gain (Loss) on Investments
Net realized investment gains (losses), net of participating policyholders’ interests	1						(1)
Short term and other [Member]
Gain (Loss) on Investments
Net realized investment gains (losses), net of participating policyholders’ interests	$ 4	[1]	$ (3)	[1]	$ 10	[1]	$ (9)	[1],[2]

[1] Includes net unrealized gains (losses) related to changes in the fair value of securities for which the fair value option has been elected. There were no net unrealized gains (losses) for the three months ended June 30, 2012 or 2011. There were no net unrealized gains (losses) for the six months ended June 30, 2012 as compared with unrealized gains of $1 million for the same period in 2011.

[2] The six months ended June 30, 2011 included a $9 million loss related to the early extinguishment of debt in 2011.