Loans and ACL - Aging Analysis of Loans and Leases (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable [Line Items]
Current	$ 295,181	$ 146,985
30-89 Days Past Due	2,213	1,044
90 Days Or More Past Due	1,994	462
Nonperforming	454	522
Total	299,842	149,013
Commercial: | Commercial and industrial
Financing Receivable [Line Items]
Current	129,873	61,701
30-89 Days Past Due	94	34
90 Days Or More Past Due	1	0
Nonperforming	212	200
Total	130,180	61,935
Commercial: | CRE
Financing Receivable [Line Items]
Current	26,817	16,741
30-89 Days Past Due	5	4
90 Days Or More Past Due	0	0
Nonperforming	10	63
Total	26,832	16,808
Commercial: | Lease financing
Financing Receivable [Line Items]
Current	6,112	2,014
30-89 Days Past Due	2	1
90 Days Or More Past Due	0	0
Nonperforming	8	3
Total	6,122	2,018
Commercial: | Commercial construction
Financing Receivable [Line Items]
Current	6,204	4,249
30-89 Days Past Due	1	1
90 Days Or More Past Due	0	0
Nonperforming	0	2
Total	6,205	4,252
Consumer: | Residential Mortgage
Financing Receivable [Line Items]
Current	50,975	30,413
30-89 Days Past Due	498	456
90 Days Or More Past Due	543	405
Nonperforming	55	119
Total	52,071	31,393
Consumer: | Residential home equity and direct
Financing Receivable [Line Items]
Current	26,846	11,651
30-89 Days Past Due	122	63
90 Days Or More Past Due	9	8
Nonperforming	67	53
Total	27,044	11,775
Consumer: | Indirect other
Financing Receivable [Line Items]
Current	11,011	6,097
30-89 Days Past Due	85	46
90 Days Or More Past Due	2	0
Nonperforming	2	0
Total	11,100	6,143
Consumer: | Indirect auto
Financing Receivable [Line Items]
Current	23,771	10,804
30-89 Days Past Due	560	390
90 Days Or More Past Due	11	6
Nonperforming	100	82
Total	24,442	11,282
Consumer: | Student
Financing Receivable [Line Items]
Current	5,905
30-89 Days Past Due	650
90 Days Or More Past Due	188
Nonperforming	0
Total	6,743
Credit card
Financing Receivable [Line Items]
Current	5,541	2,902
30-89 Days Past Due	56	26
90 Days Or More Past Due	22	13
Nonperforming	0	0
Total	5,619	2,941
PCI
Financing Receivable [Line Items]
Current	2,126	413
30-89 Days Past Due	140	23
90 Days Or More Past Due	1,218	30
Nonperforming	0	0
Total	$ 3,484	$ 466