Loans - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	$ 57,100,000,000			$ 56,400,000,000
Value of loans transferred from LHFI to LHFS	(115,000,000)		(57,000,000)
Transfer of Loans Held-for-sale to Portfolio Loans	17,000,000		12,000,000
Loans held for investment sold	85,000,000		503,000,000
Gain (Loss) on Sales of Loans, Net	9,000,000		4,000,000
Loans and Leases Receivable, Impaired, Commitment to Lend	8,000,000			8,000,000
Loans held for investment	129,196,000,000	[1]		127,877,000,000	[1]
Accrual Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,728,000,000			2,700,000,000
Accruing TDRs current	96.00%			96.00%
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	65,709,000,000			64,310,000,000
Federally Guaranteed Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Loan Portfolio Current	82.00%			81.00%
Loans held for investment	5,533,000,000			5,545,000,000
Residential Guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Loan Portfolio Current	83.00%			82.00%
Loans held for investment	3,295,000,000			3,416,000,000
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	42,795,000,000			43,190,000,000
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	14,637,000,000	[2]		14,809,000,000	[2]
Minimum [Member] | Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans And Leases Receivable Individually Evaluated For Impairment	3,000,000
Cross-Border Outstanding Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Foreign	1,100,000,000			1,000,000,000
Credit Concentration Risk [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	42,800,000,000			43,200,000,000
ResidentialLoansInterestOnlyHighOriginalLTVAndOrSecondLien	12,200,000,000			12,400,000,000
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan subcategory as a percent of total loans	33.00%			34.00%
Government guaranteed percent	8.00%			8.00%
Home Equity Line of Credit [Member] | Credit Concentration Risk [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unused Commitments to Extend Credit	11,100,000,000			11,200,000,000
Mortgage Loans on Real Estate [Member] | Credit Concentration Risk [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unused Commitments to Extend Credit	2,800,000,000			2,700,000,000
Residential Mortgage Interest Only Loans [Member] | Credit Concentration Risk [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ResidentialLoansInterestOnlyHighOriginalLTVAndOrSecondLien	5,200,000,000			5,500,000,000
LoansWithNoMortgageInsuranceAndFirstLienHighOriginalLTVOrSecondLien [Member] | Residential Mortgage Interest Only Loans [Member] | Credit Concentration Risk [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ResidentialLoansInterestOnlyHighOriginalLTVAndOrSecondLien	1,073,000,000			1,100,000,000
LoansWithNoMortgageInsuranceAndFirstLienHighOriginalLTVOrSecondLien [Member] | Residential Mortgage Amortizing Loans [Member] | Credit Concentration Risk [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
ResidentialLoansInterestOnlyHighOriginalLTVAndOrSecondLien	$ 7,000,000,000			$ 6,900,000,000

[1] Includes loans of consolidated VIEs of $318 million and $327 million at March 31, 2014 and December 31, 2013, respectively.

[2] Excludes $3.3 billion and $3.4 billion at March 31, 2014 and December 31, 2013, respectively, of guaranteed residential loans. At March 31, 2014 and December 31, 2013, the majority of these loans had FICO scores of 700 and above.