Derivatives (Net Derivative Gains Losses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Components of Net Derivatives Gains (Losses)
Derivatives and hedging gains (losses)	$ (4,536)	$ 277	$ 1,638
Embedded derivatives gains (losses)	(2,224)	(239)	(321)
Total net derivative gains (losses)	$ (6,760)	$ 38	$ 1,317