Investments (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning Balance	$ 168	$ 177	$ 170	$ 194
Additional credit impairments on:
Previously impaired securities	0	0	1	0
Securities without prior impairments	0	0	0	0
Reductions due to sales or redemptions	(2)	(2)	(5)	(19)
Ending Balance	$ 166	$ 175	$ 166	$ 175