Loans and ACL - Aging Analysis of Loans and Leases (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable [Line Items]
Current	$ 314,073	$ 295,181
30-89 Days Past Due	2,374	2,213
90 Days Or More Past Due	1,748	1,994
Nonperforming	1,034	454
Total	319,229	299,842
Commercial: | Commercial and industrial
Financing Receivable [Line Items]
Current	148,451	129,873
30-89 Days Past Due	262	94
90 Days Or More Past Due	5	1
Nonperforming	443	212
Total	149,161	130,180
Commercial: | CRE
Financing Receivable [Line Items]
Current	27,505	26,817
30-89 Days Past Due	8	5
90 Days Or More Past Due	1	0
Nonperforming	18	10
Total	27,532	26,832
Commercial: | Commercial construction
Financing Receivable [Line Items]
Current	6,612	6,204
30-89 Days Past Due	16	1
90 Days Or More Past Due	0	0
Nonperforming	2	0
Total	6,630	6,205
Commercial: | Lease financing
Financing Receivable [Line Items]
Current	5,949	6,112
30-89 Days Past Due	8	2
90 Days Or More Past Due	0	0
Nonperforming	27	8
Total	5,984	6,122
Consumer: | Residential Mortgage
Financing Receivable [Line Items]
Current	51,559	50,975
30-89 Days Past Due	679	498
90 Days Or More Past Due	610	543
Nonperforming	248	55
Total	53,096	52,071
Consumer: | Residential home equity and direct
Financing Receivable [Line Items]
Current	27,293	26,846
30-89 Days Past Due	156	122
90 Days Or More Past Due	10	9
Nonperforming	170	67
Total	27,629	27,044
Consumer: | Indirect auto
Financing Receivable [Line Items]
Current	24,489	23,771
30-89 Days Past Due	521	560
90 Days Or More Past Due	11	11
Nonperforming	125	100
Total	25,146	24,442
Consumer: | Indirect other
Financing Receivable [Line Items]
Current	10,903	11,011
30-89 Days Past Due	74	85
90 Days Or More Past Due	2	2
Nonperforming	1	2
Total	10,980	11,100
Consumer: | Student
Financing Receivable [Line Items]
Current	6,110	5,905
30-89 Days Past Due	593	650
90 Days Or More Past Due	1,068	188
Nonperforming	0	0
Total	7,771	6,743
Credit card
Financing Receivable [Line Items]
Current	5,202	5,541
30-89 Days Past Due	57	56
90 Days Or More Past Due	41	22
Nonperforming	0	0
Total	$ 5,300	5,619
PCI
Financing Receivable [Line Items]
Current		2,126
30-89 Days Past Due		140
90 Days Or More Past Due		1,218
Nonperforming		0
Total		$ 3,484