Investments (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning Balance	$ 192	$ 187	$ 143
Additional credit impairments on:
Previously impaired securities	0	5	44
Securities without prior impairments	3	2	8
Reductions — disposals	(1)	(2)	(8)
Ending Balance	$ 194	$ 192	$ 187