Total Equity and Other Comprehensive Income (Accumulated Other Comprehensive Income (Loss) Components) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Net Unrealized Gains Losses on Non Otti Securities [Abstract]
Net unrealized gains (losses) on non-OTTI securities, after-tax, Beginning Balance	$ 286	$ 647
Other Comprehensive Income (Loss), Non Otti Securities Adjustment, After Tax	319	47
Net unrealized gains (losses) on non-OTTI securities, after-tax, Ending Balance	605	694
Net Unrealized Gains Losses On Otti Securities [Abstract]
Net unrealized gains (losses) on OTTI securities, after tax, Beginning Balance	66	74
Other Comprehensive Income Loss Otti Securities Adjustment After Tax	(24)	2
Net unrealized gains (losses) on OTTI securities, after tax, Ending Balance	42	76
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax [Abstract]
Net unrealized gains (losses) on cash flow hedge derivatives, after-tax, Beginning balance	430	350
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	127	151
Net unrealized gains (losses) on cash flow hedge derivatives, after-tax, Ending balance	557	501
Pension and other postretirement benefit plan adjustments [Abstract]
Pension and other postretirement benefit plan adjustments, after tax, Beginning Balance	(554)	(520)
Pension and other postretirement benefit plan adjustments, net activity, After Tax	8	38
Pension and other postretirement benefit plan adjustments, after tax, Ending Balance	(546)	(482)
Other Comprehensive Income Other Adjustments [Abstract]
Other, after tax, Beginning balance	(98)	(48)
Total Other, net activity, After tax	(28)	(38)
Other, after tax, Ending balance	(126)	(86)
Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance	130	503
Other comprehensive income (loss), after tax and net of reclassifications into Net income	402	200
Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance	$ 532	$ 703