LHFI by Credit Quality Indicator (Additional Information) (Detail) - USD ($) $ in Millions		Mar. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other Real Estate	[1]	$ 62	$ 60
Loans and Leases Receivable, Gross	[2]	143,529	143,298
Federal National Mortgage Association (FNMA) Insured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		549	537
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		6,396	6,167
Federal Reserve Bank Advances [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Line of Credit Facility, Remaining Borrowing Capacity		$ 17,000	$ 17,000

[1] Does not include foreclosed real estate related to loans insured by the FHA or guaranteed by the VA. Proceeds due from the FHA and the VA are recorded as a receivable in other assets in the Consolidated Balance Sheets until the property is conveyed and the funds are received. The receivable related to proceeds due from the FHA or the VA totaled $50 million at both March 31, 2017 and December 31, 2016.

[2] Includes loans of consolidated VIEs of $201 million and $211 million at March 31, 2017 and December 31, 2016, respectively.