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		6 Months Ended
	Jun. 30, 2014 SecurityLoan	Jun. 30, 2013 SecurityLoan	Jun. 30, 2014 SecurityLoan	Jun. 30, 2013 SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans	2,010	2,885	4,034	9,590
Amount Defaulted	$ 48	$ 177	$ 109	$ 758
Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	150	172	295	340
Amount Defaulted	3	3	8	5
Commercial Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	6	23	12	42
Amount Defaulted	3	44	10	72
Residential Mortgages [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	129	187	277	370
Amount Defaulted	17	28	39	59
Credit Card [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1,460	1,638	2,921	3,624
Amount Defaulted	8	10	16	21
Other Retail [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	158	369	343	886
Amount Defaulted	4	15	10	43
Total Loans, Excluding GNMA and Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	1,903	2,389	3,848	5,262
Amount Defaulted	35	100	83	200
Loans Purchased from GNMA Mortgage Pools [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	105	481	176	4,303
Amount Defaulted	12	68	22	546
Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	2	15	10	25
Amount Defaulted	$ 1	$ 9	$ 4	$ 12