Changes in Accumulated Other Comprehensive (Loss) Income (Details 1) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other non-interest revenue	$ 377	$ 361
Interest expense on long-term debt and other	351	294
Other expenses	1,434	1,370
Net Unrealized Gains (Losses) on Investment Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase (decrease) due to amounts reclassified into earnings	0	0
Foreign Currency Translation Adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase (decrease) due to amounts reclassified into earnings	0	0
Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase (decrease) due to amounts reclassified into earnings	0	0
Reclassification out of accumulated other comprehensive income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase (decrease) due to amounts reclassified into earnings	0	0
Reclassification out of accumulated other comprehensive income [Member] | Net Unrealized Gains (Losses) on Investment Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other non-interest revenue	0	0
Income tax provision for other non-interest revenue	0	0
Other non-interest revenue, net of taxes	0	0
Reclassification out of accumulated other comprehensive income [Member] | Foreign Currency Translation Adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other expenses	1	0
Income tax benefit for other, net expense	(1)	0
Other, net expense, net of taxes	$ 0	$ 0