Summary of Loans by Portfolio Type (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 212,989		$ 203,222
30-89 Days Past Due	1,473		1,782
90 Days or More Past Due	1,326		1,753
Nonperforming	2,362		3,078
Total	218,150		209,835
Commercial Loan
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	62,502		55,991
30-89 Days Past Due	216		300
90 Days or More Past Due	40		45
Nonperforming	152		312
Total	62,910		56,648
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	36,105		34,800
30-89 Days Past Due	65		138
90 Days or More Past Due	12		14
Nonperforming	631		899
Total	36,813		35,851
Residential Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	40,451	[1]	35,664	[1]
30-89 Days Past Due	393	[1]	404	[1]
90 Days or More Past Due	301	[1]	364	[1]
Nonperforming	757	[1]	650	[1]
Total	41,902	[1]	37,082	[1]
Credit Card
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	15,815		16,662
30-89 Days Past Due	230		238
90 Days or More Past Due	194		236
Nonperforming	163		224
Total	16,402		17,360
Other Retail
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	47,358		47,516
30-89 Days Past Due	300		340
90 Days or More Past Due	97		184
Nonperforming	210		67
Total	47,965		48,107
Total Loans, Excluding Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	202,231		190,633
30-89 Days Past Due	1,204		1,420
90 Days or More Past Due	644		843
Nonperforming	1,913		2,152
Total	205,992		195,048
Covered loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	10,758		12,589
30-89 Days Past Due	269		362
90 Days or More Past Due	682		910
Nonperforming	449		926
Total	$ 12,158		$ 14,787

[1] At September 30, 2012, $462 million of loans 30 - 89 days past due and $3.0 billion of loans 90 days or more past due purchased from Government National Mortgage Association ("GNMA") mortgage pools whose repayments are insured by the Federal Housing Administration or guaranteed by the Department of Veterans Affairs, were classified as current, compared with $545 million and $2.6 billion at December 31, 2011, respectively.