Loans and Allowance for Credit Losses - Summary of Loans by Portfolio Type (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 219,136	$ 218,204
Accruing 30-89 Days Past Due	1,205	1,723
90 Days or More Past Due	1,165	1,323
Nonperforming	1,845	2,079
Total	223,351	223,329
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	65,995	65,701
Accruing 30-89 Days Past Due	164	341
90 Days or More Past Due	63	58
Nonperforming	101	123
Total	66,323	66,223
Commercial real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	36,801	36,241
Accruing 30-89 Days Past Due	84	158
90 Days or More Past Due	8	8
Nonperforming	507	546
Total	37,400	36,953
Residential mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	44,740	42,728
Accruing 30-89 Days Past Due	322	348
90 Days or More Past Due	249	281
Nonperforming	673	661
Total	45,984	44,018
Credit card [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	15,696	16,525
Accruing 30-89 Days Past Due	202	227
90 Days or More Past Due	204	217
Nonperforming	127	146
Total	16,229	17,115
Other retail [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	46,128	47,109
Accruing 30-89 Days Past Due	239	290
90 Days or More Past Due	85	96
Nonperforming	228	217
Total	46,680	47,712
Total loans, excluding covered loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	209,360	208,304
Accruing 30-89 Days Past Due	1,011	1,364
90 Days or More Past Due	609	660
Nonperforming	1,636	1,693
Total	212,616	212,021
Covered loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	9,776	9,900
Accruing 30-89 Days Past Due	194	359
90 Days or More Past Due	556	663
Nonperforming	209	386
Total	$ 10,735	$ 11,308