LHFI by Credit Quality Indicator (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 121,817	[1]	$ 122,495	[1]
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	23,925	[2]	23,243	[2]
Federally Guaranteed Residential Loans [Member] | Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	4,800		6,700
Loans Held For Investment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	121,817		122,495
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	19,539		19,963
Consumer Portfolio Segment [Member] | Guaranteed Student Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	5,823		7,199
Consumer Portfolio Segment [Member] | Loans Held For Investment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment			19,963
Consumer Portfolio Segment [Member] | Loans Held For Investment [Member] | Guaranteed Student Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 5,823		$ 7,199

[1] 2 Includes loans of consolidated VIEs374 3,322

[2] Excludes $4.8 billion and $6.7 billion at September 30, 2012 and December 31, 2011, respectively, of guaranteed residential loans. At both September 30, 2012 and December 31, 2011, the majority of these loans had FICO scores of 700 and above.