Investments (OTTI rollforward) (Details 6) - 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 [Line Items]
Beginning balance	$ 85	$ 148	$ 98	$ 147
Credit losses for which an other-than-temporary impairment was previously recognized	0	0	1	1
Reductions for securities sold during the period (realized)	0	(50)	(14)	(50)
Ending balance	$ 85	$ 98	$ 85	$ 98