LHFI by Credit Quality Indicator (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 120,804	[1]	$ 121,470	[1]
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	54,343		54,048
Commercial and Industrial | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	52,506		52,292
Commercial and Industrial | Criticized Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,632		1,562
Commercial and Industrial | Criticized Nonaccruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	205		194
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	4,261		4,127
Commercial Real Estate | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	3,767		3,564
Commercial Real Estate | Criticized Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	435		497
Commercial Real Estate | Criticized Nonaccruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	59		66
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	634		713
Commercial Construction [Member] | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	440		506
Commercial Construction [Member] | Criticized Accruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	169		173
Commercial Construction [Member] | Criticized Nonaccruing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	25		34
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	23,051	[2]	23,389	[2]
Residential Nonguaranteed [Member] | FICO Score 700 and Above
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	17,168	[2]	17,410	[2]
Residential Nonguaranteed [Member] | FICO Score Between 620 and 699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	3,848	[2]	3,850	[2]
Residential Nonguaranteed [Member] | FICO Score Below 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,035	[2],[3]	2,129	[2],[3]
Home Equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	14,617	[2]	14,805	[2]
Home Equity | FICO Score 700 and Above
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	11,202	[2]	11,339	[2]
Home Equity | FICO Score Between 620 and 699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,291	[2]	2,297	[2]
Home Equity | FICO Score Below 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,124	[2],[3]	1,169	[2],[3]
Residential Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	683	[2]	753	[2]
Residential Construction | FICO Score 700 and Above
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	515	[2]	561	[2]
Residential Construction | FICO Score Between 620 and 699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	113	[2]	123	[2]
Residential Construction | FICO Score Below 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	55	[2],[3]	69	[2],[3]
Consumer Other Direct
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,387	[4]	2,396	[4]
Consumer Other Direct | FICO Score 700 and Above
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,952	[4]	1,980	[4]
Consumer Other Direct | FICO Score Between 620 and 699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	368	[4]	350	[4]
Consumer Other Direct | FICO Score Below 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	67	[3],[4]	66	[3],[4]
Consumer Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	11,009	[4]	10,998	[4]
Consumer Indirect | FICO Score 700 and Above
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	8,270	[4]	8,300	[4]
Consumer Indirect | FICO Score Between 620 and 699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	2,084	[4]	2,038	[4]
Consumer Indirect | FICO Score Below 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	655	[3],[4]	660	[3],[4]
Consumer Credit Card
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	614	[4]	632	[4]
Consumer Credit Card | FICO Score 700 and Above
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	418	[4]	435	[4]
Consumer Credit Card | FICO Score Between 620 and 699
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	153	[4]	152	[4]
Consumer Credit Card | FICO Score Below 620
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 43	[3],[4]	$ 45	[3],[4]

[1] 2 Includes loans of consolidated VIEs355 365

[2] Excludes $3.9 billion and $4.3 billion at March 31, 2013 and December 31, 2012, respectively, of guaranteed residential loans. At March 31, 2013 and December 31, 2012, the majority of these loans had FICO scores of 700 and above.

[3] For substantially all loans with refreshed FICO scores below 620, the borrower’s FICO score at the time of origination exceeded 620 but has since deteriorated as the loan has seasoned.

[4] Excludes $5.3 billion and $5.4 billion at March 31, 2013 and December 31, 2012, respectively, of guaranteed student loans.