Investments and Derivative Instruments Level 4 Other-Than-Temporary Impairment Losses (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other-Than-Temporary Impairment Losses [Roll Forward]
Other than Temporary Impairment, as of Jan. 1	$ (552)	$ (1,013)	$ (1,676)
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, No Previous Impairment	(15)	(19)	(28)
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, Additional Credit Losses	22	13	20
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Securities Sold	138	469	700
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Change in Status	0	2	0
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Reductions, Cash Flows	27	22	11
Other than Temporary Impairment, as of Dec. 31	$ (424)	$ (552)	$ (1,013)