Loans and ACL - Aging Analysis of Loans and Leases (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable [Line Items]
Current	$ 147,571	$ 146,985
30-89 Days Past Due	992	1,044
90 Days Or More Past Due	403	462
Nonperforming	447	522
Total	149,413	149,013
Commercial | Commercial and industrial
Financing Receivable [Line Items]
Current	64,118	61,701
30-89 Days Past Due	34	34
90 Days Or More Past Due	0	0
Nonperforming	172	200
Total	64,324	61,935
Commercial | CRE
Financing Receivable [Line Items]
Current	20,854	20,990
30-89 Days Past Due	1	5
90 Days Or More Past Due	0	0
Nonperforming	29	65
Total	20,884	21,060
Commercial | Lease financing
Financing Receivable [Line Items]
Current	2,353	2,014
30-89 Days Past Due	1	1
90 Days Or More Past Due	0	0
Nonperforming	2	3
Total	2,356	2,018
Retail | Residential mortgage
Financing Receivable [Line Items]
Current	27,412	30,413
30-89 Days Past Due	432	456
90 Days Or More Past Due	347	405
Nonperforming	106	119
Total	28,297	31,393
Retail | Direct
Financing Receivable [Line Items]
Current	11,346	11,463
30-89 Days Past Due	54	61
90 Days Or More Past Due	7	7
Nonperforming	56	53
Total	11,463	11,584
Retail | Indirect
Financing Receivable [Line Items]
Current	17,947	16,901
30-89 Days Past Due	423	436
90 Days Or More Past Due	9	6
Nonperforming	82	82
Total	18,461	17,425
Revolving credit
Financing Receivable [Line Items]
Current	3,194	3,090
30-89 Days Past Due	31	28
90 Days Or More Past Due	16	14
Nonperforming	0	0
Total	3,241	3,132
PCI
Financing Receivable [Line Items]
Current	347	413
30-89 Days Past Due	16	23
90 Days Or More Past Due	24	30
Nonperforming	0	0
Total	$ 387	$ 466