Loans and Allowance for Credit Losses - Summary of Loans by Portfolio Type and Deliquency Status (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 223,881	$ 218,204
Accruing 30-89 Days Past Due	1,262	1,723
90 Days or More Past Due	1,119	1,323
Nonperforming	1,713	2,079
Total loans, excluding covered loans	217,990	212,021
Total loans	227,975	223,329
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	67,836	65,701
Accruing 30-89 Days Past Due	184	341
90 Days or More Past Due	60	58
Nonperforming	105	123
Total loans, excluding covered loans	68,185	66,223
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	37,775	36,241
Accruing 30-89 Days Past Due	89	158
90 Days or More Past Due	10	8
Nonperforming	424	546
Total loans, excluding covered loans	38,298	36,953
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	46,446	42,728
Accruing 30-89 Days Past Due	371	348
90 Days or More Past Due	251	281
Nonperforming	685	661
Total loans, excluding covered loans	47,753	44,018
Credit Card [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	16,163	16,525
Accruing 30-89 Days Past Due	194	227
90 Days or More Past Due	183	217
Nonperforming	109	146
Total loans, excluding covered loans	16,649	17,115
Other Retail [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	46,564	47,109
Accruing 30-89 Days Past Due	243	290
90 Days or More Past Due	76	96
Nonperforming	222	217
Total loans, excluding covered loans	47,105	47,712
Total Loans, Excluding Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	214,784	208,304
Accruing 30-89 Days Past Due	1,081	1,364
90 Days or More Past Due	580	660
Nonperforming	1,545	1,693
Total loans, excluding covered loans	217,990	212,021
Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	9,097	9,900
Accruing 30-89 Days Past Due	181	359
90 Days or More Past Due	539	663
Nonperforming	168	386
Total loans	$ 9,985	$ 11,308