Investments and Derivative Instruments Level 4 Other-Than-Temporary Impairment Losses (Details) - 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 Losses [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Period Increase (Decrease)	$ 2	$ 3	$ 8	$ 10
Balance as of beginning of period	(288)	(382)	(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	0	3	0	6
Securities that matured or were sold during the period	3	29	5	59
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Change in Status	0	0	22	9
Securities due to an increase in expected cash flows	15	5	1	0
Balance as of end of period	$ (270)	$ (351)	$ (270)	$ (351)