Loans - Additional Information (Detail) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Sep. 30, 2014		Sep. 30, 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			$ 57,100,000,000			$ 56,400,000,000
Loans transferred from loans to loans held for sale	362,000,000		56,000,000	3,183,000,000		200,000,000
Transfer of Loans Held-for-sale to Portfolio Loans	19,000,000		11,000,000	39,000,000		28,000,000
Loans held for investment sold	2,300,000,000		99,000,000	3,000,000,000		761,000,000
Gain (Loss) on Sales of Loans, Net	40,000,000		1,000,000	71,000,000		7,000,000
Loans and Leases Receivable, Impaired, Commitment to Lend	6,000,000			6,000,000			8,000,000
Loans held for investment	132,151,000,000	[1]		132,151,000,000	[1]		127,877,000,000	[1]
Impaired Financing Receivable, Interest Income, Cash Basis Method	1,000,000		1,000,000	2,000,000		6,000,000
Accrual Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,500,000,000			2,500,000,000			2,700,000,000
Accruing TDRs current	97.00%			97.00%			96.00%
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	71,094,000,000			71,094,000,000			64,310,000,000
Federally Guaranteed Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of Loan Portfolio Current	82.00%			82.00%			81.00%
Loans held for investment	5,314,000,000			5,314,000,000			5,545,000,000
Residential Guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment sold	2,000,000,000
Percentage of Loan Portfolio Current	30.00%			30.00%			82.00%
Loans held for investment	651,000,000			651,000,000			3,416,000,000
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	39,222,000,000			39,222,000,000			43,190,000,000
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	14,389,000,000	[2]		14,389,000,000	[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			3,000,000
Cross-Border Outstanding Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross, Foreign	1,300,000,000			1,300,000,000			956,000,000
Credit Concentration Risk [Member] | Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	39,200,000,000			39,200,000,000			43,200,000,000
ResidentialLoansInterestOnlyHighOriginalLTVAndOrSecondLien	11,700,000,000			11,700,000,000			12,400,000,000
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan subcategory as a percent of total loans	30.00%			30.00%			34.00%
Government guaranteed percent	2.00%			2.00%			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	10,900,000,000			10,900,000,000			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	3,400,000,000			3,400,000,000			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	4,400,000,000			4,400,000,000			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	919,000,000			919,000,000			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	$ 7,300,000,000			$ 7,300,000,000			$ 6,900,000,000

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

[2] Excludes $651 million and $3.4 billion at September 30, 2014 and December 31, 2013, respectively, of guaranteed residential loans. At September 30, 2014 and December 31, 2013, the majority of these loans had FICO scores of 700 and above.