Loans and Allowance for Credit Losses - Summary of Loans by Portfolio Class and Delinquency Status of those that Continue to Accrue Interest and are Nonperforming (Detail) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 274,506	$ 269,994
Accruing 30-89 Days Past Due	996	1,081
Accruing 90 Days or More Past Due	639	764
Nonperforming	1,142	1,368
Total loans, excluding covered loans	273,846	269,371
Total loans	277,283	273,207
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	96,205	92,588
Accruing 30-89 Days Past Due	258	263
Accruing 90 Days or More Past Due	51	52
Nonperforming	322	483
Total loans, excluding covered loans	96,836	93,386
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	41,753	42,922
Accruing 30-89 Days Past Due	34	44
Accruing 90 Days or More Past Due	2	8
Nonperforming	119	124
Total loans, excluding covered loans	41,908	43,098
Residential Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	58,022	56,372
Accruing 30-89 Days Past Due	126	151
Accruing 90 Days or More Past Due	118	156
Nonperforming	530	595
Total loans, excluding covered loans	58,796	57,274
Other Retail [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	54,935	53,340
Accruing 30-89 Days Past Due	275	284
Accruing 90 Days or More Past Due	77	83
Nonperforming	158	157
Total loans, excluding covered loans	55,445	53,864
Credit Card [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	20,377	21,209
Accruing 30-89 Days Past Due	254	284
Accruing 90 Days or More Past Due	229	253
Nonperforming	1	3
Total loans, excluding covered loans	20,861	21,749
Total Loans, Excluding Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	271,292	266,431
Accruing 30-89 Days Past Due	947	1,026
Accruing 90 Days or More Past Due	477	552
Nonperforming	1,130	1,362
Total loans, excluding covered loans	273,846	269,371
Covered Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	3,214	3,563
Accruing 30-89 Days Past Due	49	55
Accruing 90 Days or More Past Due	162	212
Nonperforming	12	6
Total loans	$ 3,437	$ 3,836