Loans and ACL - Aging Analysis of Loans and Leases (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable [Line Items]
Current	$ 146,985	$ 141,531
30-89 Days Past Due	1,044	1,052
90 Days Or More Past Due	462	548
Nonperforming	522	570
Total	149,013	143,701
Commercial | Commercial and industrial
Financing Receivable [Line Items]
Current	61,701	58,852
30-89 Days Past Due	34	41
90 Days Or More Past Due	0	1
Nonperforming	200	259
Total	61,935	59,153
Commercial | CRE
Financing Receivable [Line Items]
Current	20,990	21,209
30-89 Days Past Due	5	8
90 Days Or More Past Due	0	1
Nonperforming	65	45
Total	21,060	21,263
Commercial | Lease financing
Financing Receivable [Line Items]
Current	2,014	1,906
30-89 Days Past Due	1	4
90 Days Or More Past Due	0	0
Nonperforming	3	1
Total	2,018	1,911
Retail | Residential mortgage
Financing Receivable [Line Items]
Current	30,413	27,659
30-89 Days Past Due	456	472
90 Days Or More Past Due	405	465
Nonperforming	119	129
Total	31,393	28,725
Retail | Direct
Financing Receivable [Line Items]
Current	11,463	11,756
30-89 Days Past Due	61	65
90 Days Or More Past Due	7	6
Nonperforming	53	64
Total	11,584	11,891
Retail | Indirect
Financing Receivable [Line Items]
Current	16,901	16,745
30-89 Days Past Due	436	412
90 Days Or More Past Due	6	6
Nonperforming	82	72
Total	17,425	17,235
Revolving credit
Financing Receivable [Line Items]
Current	3,090	2,837
30-89 Days Past Due	28	23
90 Days Or More Past Due	14	12
Nonperforming	0	0
Total	3,132	2,872
PCI
Financing Receivable [Line Items]
Current	413	567
30-89 Days Past Due	23	27
90 Days Or More Past Due	30	57
Nonperforming	0	0
Total	$ 466	$ 651