Derivatives (Net Derivative Gains Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Components of Net Derivatives Gains (Losses)
Derivatives and hedging gains (losses)	$ (506)	$ 2,525	$ (2,010)	$ 5,029
Embedded derivatives gains (losses)	69	(4,624)	647	(5,793)
Total net derivative gains (losses)	$ (437)	$ (2,099)	$ (1,363)	$ (764)