Loans and Allowance for Credit Losses - Schedule of Loans Modified as TDRs that have Subsequently been Fully or Partially Charged-Off or Became 90 Days or More Past Due (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014 SecurityLoan	Mar. 31, 2013 SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans	2,024	6,705
Amount Defaulted	$ 61	$ 581
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	145	168
Amount Defaulted	5	2
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	6	19
Amount Defaulted	7	28
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	148	183
Amount Defaulted	22	31
Credit Card [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1,461	1,986
Amount Defaulted	8	11
Other Retail [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	185	517
Amount Defaulted	6	28
Total Loans, Excluding GNMA and Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1,945	2,873
Amount Defaulted	48	100
Loans Purchased from GNMA Mortgage Pools [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	71	3,822
Amount Defaulted	10	478
Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	8	10
Amount Defaulted	$ 3	$ 3