Loans and ACL - Risk Rating (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable
Loans and leases	$ 299,842	$ 149,013
Commercial: | Commercial & Industrial
Financing Receivable
Loans and leases	130,180	61,935
Commercial: | Commercial & Industrial | Pass
Financing Receivable
Loans and leases	127,229	60,655
Commercial: | Commercial & Industrial | Special mention
Financing Receivable
Loans and leases	1,264	216
Commercial: | Commercial & Industrial | Substandard-performing
Financing Receivable
Loans and leases	1,475	864
Commercial: | Commercial & Industrial | Nonperforming
Financing Receivable
Loans and leases	212	200
Commercial: | CRE
Financing Receivable
Loans and leases	26,832	16,808
Commercial: | CRE | Pass
Financing Receivable
Loans and leases	26,393	16,509
Commercial: | CRE | Special mention
Financing Receivable
Loans and leases	145	45
Commercial: | CRE | Substandard-performing
Financing Receivable
Loans and leases	284	191
Commercial: | CRE | Nonperforming
Financing Receivable
Loans and leases	10	63
Commercial: | Commercial construction
Financing Receivable
Loans and leases	6,205	4,252
Commercial: | Commercial construction | Pass
Financing Receivable
Loans and leases	6,037	4,203
Commercial: | Commercial construction | Special mention
Financing Receivable
Loans and leases	37	16
Commercial: | Commercial construction | Substandard-performing
Financing Receivable
Loans and leases	131	31
Commercial: | Commercial construction | Nonperforming
Financing Receivable
Loans and leases	0	2
Commercial: | Lease Financing
Financing Receivable
Loans and leases	6,122	2,018
Commercial: | Lease Financing | Pass
Financing Receivable
Loans and leases	6,039	2,012
Commercial: | Lease Financing | Special mention
Financing Receivable
Loans and leases	19	0
Commercial: | Lease Financing | Substandard-performing
Financing Receivable
Loans and leases	56	3
Commercial: | Lease Financing | Nonperforming
Financing Receivable
Loans and leases	8	3
Consumer: | Residential Mortgage
Financing Receivable
Loans and leases	52,071	31,393
Consumer: | Residential Mortgage | Performing
Financing Receivable
Loans and leases	52,016	31,274
Consumer: | Residential Mortgage | Nonperforming
Financing Receivable
Loans and leases	55	119
Consumer: | Residential home equity and direct
Financing Receivable
Loans and leases	27,044	11,775
Consumer: | Residential home equity and direct | Performing
Financing Receivable
Loans and leases	26,977	11,722
Consumer: | Residential home equity and direct | Nonperforming
Financing Receivable
Loans and leases	67	53
Consumer: | Indirect auto
Financing Receivable
Loans and leases	24,442	11,282
Consumer: | Indirect auto | Performing
Financing Receivable
Loans and leases	24,342	11,200
Consumer: | Indirect auto | Nonperforming
Financing Receivable
Loans and leases	100	82
Consumer: | Indirect Other
Financing Receivable
Loans and leases	11,100	6,143
Consumer: | Indirect Other | Performing
Financing Receivable
Loans and leases	11,098	6,143
Consumer: | Indirect Other | Nonperforming
Financing Receivable
Loans and leases	$ 2	$ 0