Accumulated Other Comprehensive Income - Reclassifications from AOCI (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-interest income-other	$ 157	$ 96	$ 427	$ 176
Various	1,661	1,693	5,149	5,226
Interest income - Other	4,497	4,560	13,162	13,683
Income tax provision (benefit)	536	575	1,696	1,747
Net income	1,081	1,105	3,429	3,269
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net income	8	5	32	23
Accumulated Net Unrealized Investment Gain (Loss) | Reclassification out of Accumulated Other Comprehensive Income [Member] | Securities Available for Sale
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-interest income-other	6	0	18	3
Income tax provision (benefit)	3	0	7	1
Net income	3	0	11	2
Accumulated Net Unrealized Investment Gain (Loss) | Reclassification out of Accumulated Other Comprehensive Income [Member] | Securities Held to Maturity
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-interest income-other	(35)	(2)	(96)	(2)
Income tax provision (benefit)	(13)	(1)	(40)	(1)
Net income	(22)	(1)	(56)	(1)
Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income and non-interest income, other	47	10	119	38
Income tax provision (benefit)	18	4	45	15
Net income	29	6	74	23
Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member] | Interest rate contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest income - Other	54	23	144	65
Cash Flow Hedges | Reclassification out of Accumulated Other Comprehensive Income [Member] | Foreign exchange contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-interest income-other	(7)	(13)	(25)	(27)
Other | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Various	2	0	10	(1)
Income tax provision (benefit)	4	0	7	0
Net income	$ (2)	$ 0	$ 3	$ (1)