Loans and Allowance for Credit Losses - Composition of Loan Portfolio (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Accounts Notes And Loans Receivable Classified [Abstract]
Commercial	$ 72,286	$ 64,762
Lease financing	5,168	5,271
Total commercial	77,454	70,033
Commercial Real Estate
Commercial mortgages	32,125	32,183
Construction and development	8,672	7,702
Total commercial real estate	40,797	39,885
Residential mortgages	38,747	37,545
Home equity loans, first liens	13,218	13,611
Total residential mortgages	51,965	51,156
Credit Card	17,642	18,021
Retail leasing	6,001	5,929
Home equity and second mortgages	15,668	15,442
Revolving credit	3,216	3,276
Installment	5,978	5,709
Automobile	14,353	13,743
Student	3,352	3,579
Total other retail	48,568	47,678
Total loans, excluding covered loans	236,426	226,773
Covered loans	7,448	8,462
Total loans	$ 243,874	$ 235,235
Commercial, Percentage	29.70%	27.50%
Lease financing, Percentage	2.10%	2.30%
Total commercial, Percentage	31.80%	29.80%
Commercial mortgages, Percentage	13.20%	13.70%
Construction and development, Percentage	3.50%	3.30%
Total commercial real estate, Percentage	16.70%	17.00%
Residential mortgages, Percentage	15.90%	15.90%
Home equity loans, first liens, Percentage	5.40%	5.80%
Total residential mortgages, Percentage	21.30%	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	1.40%	1.50%
Total other retail, Percentage	19.90%	20.20%
Total loans, excluding covered loans, Percentage	96.90%	96.40%
Covered Loans, Percentage	3.10%	3.60%
Total loans, Percentage	100.00%	100.00%