LHFI by Credit Quality Indicator (Parenthetical) (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]
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	23,051	[2]	23,389	[2]
Guaranteed Student Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	5,300		5,400
Federally Guaranteed Residential Loans [Member] | Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 3,900		$ 4,300

[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.