LHFI by Credit Quality Indicator (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 121,470	[1]	$ 122,495	[1]
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	23,389	[2]	23,243	[2]
Guaranteed Student Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	5,400		7,200
Federally Guaranteed Residential Loans [Member] | Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 4,300		$ 6,700

[1] 2 Includes loans of consolidated VIEs365 3,322

[2] Excludes $4.3 billion and $6.7 billion at December 31, 2012 and 2011, respectively, of guaranteed residential loans. At both December 31, 2012 and 2011, the majority of these loans had FICO scores of 700 and above.