Investments (Details 2) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Beginning Balance	$ 166	$ 175	$ 170	$ 194
Additional credit impairments on:
Previously impaired securities	0	0	1	0
Securities without prior impairments	2	0	2	0
Reductions due to sales or redemptions	(2)	(2)	(7)	(21)
Ending Balance	$ 166	$ 173	$ 166	$ 173