Investments and Derivative Instruments Level 4 Other-Than-Temporary Impairment Losses (Details) - 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 Losses [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Period Increase (Decrease)	$ 24	$ 10	$ 32	$ 20
Balance as of beginning of period	(270)	(351)	(296)	(410)
Additions for credit impairments recognized on securities not previously impaired	0	0	(2)	(3)
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, Additional Credit Losses	12	2	12	8
Securities that matured or were sold during the period	49	48	54	107
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Change in Status	0	0	32	13
Securities due to an increase in expected cash flows	10	4	1	0
Balance as of end of period	$ (223)	$ (301)	$ (223)	$ (301)