Changes in Accumulated Other Comprehensive (Loss) Income (Details 1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other non-interest revenue	$ 436	$ 483	$ 1,284	$ 1,514
Interest expense on long-term debt and other	354	280	994	841
Other expenses	1,498	1,498	4,281	3,388
Increase (decrease) due to amounts reclassified into earnings		3
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	(1)	0	(3)
Foreign Currency Translation Adjustments [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase (decrease) due to amounts reclassified into earnings	(1)	0	(1)	0
Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase (decrease) due to amounts reclassified into earnings	(1)	(1)	(1)	(3)
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	1	0	5
Income tax provision for other non-interest revenue	0	0	0	(2)
Other non-interest revenue, net of taxes	0	1	0	3
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	(6)	0	(6)	0
Income tax benefit for other, net expense	7	0	7	0
Other, net expense, net of taxes	1	0	1	0
Reclassification out of accumulated other comprehensive income [Member] | Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase (decrease) due to amounts reclassified into earnings	$ 1	$ 1	$ 1	$ 3