Loans and Allowance for Credit Losses - Summary of Loans by Portfolio Type and Deliquency Status (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 227,395	$ 218,204
Accruing 30-89 Days Past Due	1,219	1,723
90 Days or More Past Due	1,105	1,323
Nonperforming	1,660	2,079
Total loans, excluding covered loans	221,983	212,021
Total loans	231,379	223,329
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	68,573	65,701
Accruing 30-89 Days Past Due	219	341
90 Days or More Past Due	50	58
Nonperforming	116	123
Total loans, excluding covered loans	68,958	66,223
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	38,253	36,241
Accruing 30-89 Days Past Due	62	158
90 Days or More Past Due	7	8
Nonperforming	356	546
Total loans, excluding covered loans	38,678	36,953
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	48,820	42,728
Accruing 30-89 Days Past Due	350	348
90 Days or More Past Due	268	281
Nonperforming	732	661
Total loans, excluding covered loans	50,170	44,018
Credit Card [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	16,567	16,525
Accruing 30-89 Days Past Due	212	227
90 Days or More Past Due	190	217
Nonperforming	94	146
Total loans, excluding covered loans	17,063	17,115
Other Retail [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	46,598	47,109
Accruing 30-89 Days Past Due	234	290
90 Days or More Past Due	76	96
Nonperforming	206	217
Total loans, excluding covered loans	47,114	47,712
Total Loans, Excluding Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	218,811	208,304
Accruing 30-89 Days Past Due	1,077	1,364
90 Days or More Past Due	591	660
Nonperforming	1,504	1,693
Total loans, excluding covered loans	221,983	212,021
Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	8,584	9,900
Accruing 30-89 Days Past Due	142	359
90 Days or More Past Due	514	663
Nonperforming	156	386
Total loans	$ 9,396	$ 11,308