Summary of Impaired Loans by Portfolio Class (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	$ 7,751	[1]	$ 7,952	[1]
Unpaid Principal Balance	11,491		10,821
Valuation Allowance	837		1,005
Commitments to Lend Additional Funds	48		144
Commercial Loan
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	382	[1]	657	[1]
Unpaid Principal Balance	1,341		1,437
Valuation Allowance	40		62
Commitments to Lend Additional Funds	23		68
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	1,214	[1]	1,436	[1]
Unpaid Principal Balance	2,466		2,503
Valuation Allowance	75		124
Commitments to Lend Additional Funds	5		25
Residential Mortgage
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	2,833	[1]	2,652	[1]
Unpaid Principal Balance	3,524		3,193
Valuation Allowance	437		482
Commitments to Lend Additional Funds			2
Credit Card
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	463	[1]	584	[1]
Unpaid Principal Balance	462		584
Valuation Allowance	167		219
Other Retail
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	408	[1]	188	[1]
Unpaid Principal Balance	455		197
Valuation Allowance	64		57
Commitments to Lend Additional Funds	7
Total loans, excluding GNMA and covered loans
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	5,300	[1]	5,517	[1]
Unpaid Principal Balance	8,248		7,914
Valuation Allowance	783		944
Commitments to Lend Additional Funds	35		95
Loans purchased from GNMA
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	1,631	[1]	1,265	[1]
Unpaid Principal Balance	1,631		1,265
Valuation Allowance	36		18
Covered loans
Financing Receivable, Impaired [Line Items]
Period-end Recorded Investment (a)	820	[1]	1,170	[1]
Unpaid Principal Balance	1,612		1,642
Valuation Allowance	18		43
Commitments to Lend Additional Funds	$ 13		$ 49

[1] Substantially all loans classified as impaired at September 30, 2012 and December 31, 2011, had an associated allowance for credit losses.