Loans and Allowance for Credit Losses - Summary of Loans by Portfolio Type and Delinquency Status of those that Continue to Accrue Interest and are Nonperforming (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 265,494	$ 257,721
Accruing 30-89 Days Past Due	914	1,105
Accruing 90 Days or More Past Due	724	831
Nonperforming	1,389	1,192
Total loans, excluding covered loans	264,287	256,253
Total loans	268,521	260,849
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	91,775	87,863
Accruing 30-89 Days Past Due	203	317
Accruing 90 Days or More Past Due	47	48
Nonperforming	489	174
Total loans, excluding covered loans	92,514	88,402
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	43,125	41,907
Accruing 30-89 Days Past Due	49	89
Accruing 90 Days or More Past Due	13	14
Nonperforming	103	127
Total loans, excluding covered loans	43,290	42,137
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	54,968	52,438
Accruing 30-89 Days Past Due	159	170
Accruing 90 Days or More Past Due	149	176
Nonperforming	628	712
Total loans, excluding covered loans	55,904	53,496
Other Retail [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	51,570	50,745
Accruing 30-89 Days Past Due	213	224
Accruing 90 Days or More Past Due	68	75
Nonperforming	157	162
Total loans, excluding covered loans	52,008	51,206
Credit Card [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	20,129	20,532
Accruing 30-89 Days Past Due	236	243
Accruing 90 Days or More Past Due	201	228
Nonperforming	5	9
Total loans, excluding covered loans	20,571	21,012
Total Loans, Excluding Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	261,567	253,485
Accruing 30-89 Days Past Due	860	1,043
Accruing 90 Days or More Past Due	478	541
Nonperforming	1,382	1,184
Total loans, excluding covered loans	264,287	256,253
Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	3,927	4,236
Accruing 30-89 Days Past Due	54	62
Accruing 90 Days or More Past Due	246	290
Nonperforming	7	8
Total loans	$ 4,234	$ 4,596