Loans and Allowance for Credit Losses - Composition of Loan Portfolio (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts Notes And Loans Receivable Classified [Abstract]
Commercial	$ 68,556	$ 64,762
Lease financing	5,145	5,271
Total commercial	73,701	70,033
Commercial Real Estate
Commercial mortgages	31,878	32,183
Construction and development	8,253	7,702
Total commercial real estate	40,131	39,885
Residential mortgages	38,316	37,545
Home equity loans, first liens	13,392	13,611
Total residential mortgages	51,708	51,156
Credit Card	17,129	18,021
Retail leasing	6,009	5,929
Home equity and second mortgages	15,261	15,442
Revolving credit	3,187	3,276
Installment	5,751	5,709
Automobile	13,933	13,743
Student	3,466	3,579
Total other retail	47,607	47,678
Total loans, excluding covered loans	230,276	226,773
Covered loans	8,099	8,462
Total loans	$ 238,375	$ 235,235
Commercial, Percentage	28.80%	27.50%
Lease financing, Percentage	2.10%	2.30%
Total commercial, Percentage	30.90%	29.80%
Commercial mortgages, Percentage	13.40%	13.70%
Construction and development, Percentage	3.40%	3.30%
Total commercial real estate, Percentage	16.80%	17.00%
Residential mortgages, Percentage	16.10%	15.90%
Home equity loans, first liens, Percentage	5.60%	5.80%
Total residential mortgages, Percentage	21.70%	21.70%
Credit Card, Percentage	7.20%	7.70%
Retail leasing, Percentage	2.50%	2.50%
Home equity and second mortgages, Percentage	6.40%	6.60%
Revolving credit, Percentage	1.30%	1.40%
Installment, Percentage	2.40%	2.40%
Automobile, Percentage	5.90%	5.80%
Student, Percentage	1.50%	1.50%
Total other retail, Percentage	20.00%	20.20%
Total loans, excluding covered loans, Percentage	96.60%	96.40%
Covered Loans, Percentage	3.40%	3.60%
Total loans, Percentage	100.00%	100.00%