Summary of Loans by Portfolio Type and Company's Internal Credit Quality Rating (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2012		Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 218,150		$ 209,835
Total outstanding commitments	442,163		423,565
Commercial Loan
Financing Receivable, Recorded Investment [Line Items]
Total loans	62,910		56,648
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	36,813		35,851
Residential Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans	41,902	[1]	37,082	[1]
Credit Card
Financing Receivable, Recorded Investment [Line Items]
Total loans	16,402		17,360
Other Retail
Financing Receivable, Recorded Investment [Line Items]
Total loans	47,965		48,107
Total Loans, Excluding Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	205,992		195,048
Covered loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	12,158		14,787
Pass Internal Credit Rating
Financing Receivable, Recorded Investment [Line Items]
Total loans	209,507		199,091
Total outstanding commitments	431,162		410,457
Pass Internal Credit Rating | Commercial Loan
Financing Receivable, Recorded Investment [Line Items]
Total loans	60,403		54,003
Pass Internal Credit Rating | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	33,326		30,733
Pass Internal Credit Rating | Residential Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans	40,666	[1]	35,814	[1]
Pass Internal Credit Rating | Credit Card
Financing Receivable, Recorded Investment [Line Items]
Total loans	16,046		16,910
Pass Internal Credit Rating | Other Retail
Financing Receivable, Recorded Investment [Line Items]
Total loans	47,522		47,665
Pass Internal Credit Rating | Total Loans, Excluding Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	197,963		185,125
Pass Internal Credit Rating | Covered loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	11,544		13,966
Special Mention Criticized Internal Credit Rating
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,213		2,070
Total outstanding commitments	3,725		3,418
Special Mention Criticized Internal Credit Rating | Commercial Loan
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,265		1,047
Special Mention Criticized Internal Credit Rating | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	785		793
Special Mention Criticized Internal Credit Rating | Residential Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans	24	[1]	19	[1]
Special Mention Criticized Internal Credit Rating | Other Retail
Financing Receivable, Recorded Investment [Line Items]
Total loans	43		24
Special Mention Criticized Internal Credit Rating | Total Loans, Excluding Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,117		1,883
Special Mention Criticized Internal Credit Rating | Covered loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	96		187
Classified Criticized
Financing Receivable, Recorded Investment [Line Items]
Total loans	6,430	[2]	8,674	[2]
Total outstanding commitments	7,276	[2]	9,690	[2]
Classified Criticized | Commercial Loan
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,242	[2]	1,598	[2]
Classified Criticized | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,702	[2]	4,325	[2]
Classified Criticized | Residential Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,212	[1],[2]	1,249	[1],[2]
Classified Criticized | Credit Card
Financing Receivable, Recorded Investment [Line Items]
Total loans	356	[2]	450	[2]
Classified Criticized | Other Retail
Financing Receivable, Recorded Investment [Line Items]
Total loans	400	[2]	418	[2]
Classified Criticized | Total Loans, Excluding Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	5,912	[2]	8,040	[2]
Classified Criticized | Covered loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	518	[2]	634	[2]
Total Criticized
Financing Receivable, Recorded Investment [Line Items]
Total loans	8,643		10,744
Total outstanding commitments	11,001		13,108
Total Criticized | Commercial Loan
Financing Receivable, Recorded Investment [Line Items]
Total loans	2,507		2,645
Total Criticized | Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Total loans	3,487		5,118
Total Criticized | Residential Mortgage
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,236	[1]	1,268	[1]
Total Criticized | Credit Card
Financing Receivable, Recorded Investment [Line Items]
Total loans	356		450
Total Criticized | Other Retail
Financing Receivable, Recorded Investment [Line Items]
Total loans	443		442
Total Criticized | Total Loans, Excluding Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	8,029		9,923
Total Criticized | Covered loans
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 614		$ 821

[1] At September 30, 2012, $3.0 billion of GNMA loans 90 days or more past due and $2.2 billion of restructured GNMA loans whose repayments are insured by the Federal Housing Administration or guaranteed by the Department of Veterans Affairs were classified with a pass rating, compared with $2.6 billion and $2.0 billion at December 31, 2011, respectively.

[2] Classified rating on consumer loans primarily based on delinquency status.