Loans and ACL - Aging Analysis of Loans and Leases (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable [Line Items]
Current	$ 144,285	$ 141,531
30-89 Days Past Due	905	1,052
90 Days Or More Past Due	435	548
Nonperforming	558	570
Total	146,183	143,701
Commercial | Commercial and industrial
Financing Receivable [Line Items]
Current	60,205	58,852
30-89 Days Past Due	26	41
90 Days Or More Past Due	0	1
Nonperforming	243	259
Total	60,474	59,153
Commercial | CRE
Financing Receivable [Line Items]
Current	21,545	21,209
30-89 Days Past Due	4	8
90 Days Or More Past Due	0	1
Nonperforming	61	45
Total	21,610	21,263
Commercial | Lease financing
Financing Receivable [Line Items]
Current	1,913	1,906
30-89 Days Past Due	2	4
90 Days Or More Past Due	0	0
Nonperforming	9	1
Total	1,924	1,911
Retail | Residential mortgage
Financing Receivable [Line Items]
Current	29,031	27,659
30-89 Days Past Due	441	472
90 Days Or More Past Due	374	465
Nonperforming	119	129
Total	29,965	28,725
Retail | Direct
Financing Receivable [Line Items]
Current	11,547	11,756
30-89 Days Past Due	52	65
90 Days Or More Past Due	4	6
Nonperforming	58	64
Total	11,661	11,891
Retail | Indirect
Financing Receivable [Line Items]
Current	16,731	16,745
30-89 Days Past Due	337	412
90 Days Or More Past Due	4	6
Nonperforming	68	72
Total	17,140	17,235
Revolving credit
Financing Receivable [Line Items]
Current	2,845	2,837
30-89 Days Past Due	21	23
90 Days Or More Past Due	10	12
Nonperforming	0	0
Total	2,876	2,872
PCI
Financing Receivable [Line Items]
Current	468	567
30-89 Days Past Due	22	27
90 Days Or More Past Due	43	57
Nonperforming	0	0
Total	$ 533	$ 651