LHFI by Credit Quality Indicator (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 132,151	[1]	$ 127,877	[1]
Residential Guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	651		3,416
Federally Guaranteed Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	5,314		5,545
FICO Score 700 and Above [Member] | Residential Guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	$ 651		$ 3,416

[1] Includes loans of consolidated VIEs of $298 million and $327 million at September 30, 2014 and December 31, 2013, respectively.