Investments (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
The credit portion of other-than-temporary impairments on fixed maturity securities, non-credit portion of an impairment has been recognized in other comprehensive income (loss)
Beginning Balance	$ 191	$ 190	$ 192	$ 187
Additional credit impairments on:
Previously impaired securities		1	0	4
Securities without prior impairments	0	0	0	0
Reductions-disposals	0	0	(1)	0
Ending Balance	$ 191	$ 191	$ 191	$ 191