Loans and Allowance for Credit Losses - Summary of Loans by Portfolio Type and Delinquency Status of those that Continue to Accrue Interest and are Nonperforming (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 242,011	$ 231,097
Accruing 30-89 Days Past Due	1,051	1,346
Accruing 90 Days or More Past Due	962	1,189
Nonperforming	1,567	1,603
Total loans, excluding covered loans	238,537	226,773
Total loans	245,591	235,235
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	78,453	69,587
Accruing 30-89 Days Past Due	215	257
Accruing 90 Days or More Past Due	37	55
Nonperforming	173	134
Total loans, excluding covered loans	78,878	70,033
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	40,606	39,459
Accruing 30-89 Days Past Due	50	94
Accruing 90 Days or More Past Due	12	29
Nonperforming	241	303
Total loans, excluding covered loans	40,909	39,885
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	50,662	49,695
Accruing 30-89 Days Past Due	243	358
Accruing 90 Days or More Past Due	211	333
Nonperforming	841	770
Total loans, excluding covered loans	51,957	51,156
Credit Card [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	17,403	17,507
Accruing 30-89 Days Past Due	219	226
Accruing 90 Days or More Past Due	196	210
Nonperforming	40	78
Total loans, excluding covered loans	17,858	18,021
Other Retail [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	48,453	47,156
Accruing 30-89 Days Past Due	222	245
Accruing 90 Days or More Past Due	76	86
Nonperforming	184	191
Total loans, excluding covered loans	48,935	47,678
Total Loans, Excluding Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	235,577	223,404
Accruing 30-89 Days Past Due	949	1,180
Accruing 90 Days or More Past Due	532	713
Nonperforming	1,479	1,476
Total loans, excluding covered loans	238,537	226,773
Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	6,434	7,693
Accruing 30-89 Days Past Due	102	166
Accruing 90 Days or More Past Due	430	476
Nonperforming	88	127
Total loans	$ 7,054	$ 8,462