Loans and ACL - Risk Rating (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Loans and leases	$ 152,586	$ 149,013
Commercial | Commercial & Industrial
Loans and leases	63,693	61,935
Commercial | Commercial & Industrial | Pass
Loans and leases	62,211	60,655
Commercial | Commercial & Industrial | Special mention
Loans and leases	386	216
Commercial | Commercial & Industrial | Substandard-performing
Loans and leases	903	864
Commercial | Commercial & Industrial | Nonperforming
Loans and leases	193	200
Commercial | CRE
Loans and leases	20,722	21,060
Commercial | CRE | Pass
Loans and leases	20,315	20,712
Commercial | CRE | Special mention
Loans and leases	112	61
Commercial | CRE | Substandard-performing
Loans and leases	262	222
Commercial | CRE | Nonperforming
Loans and leases	33	65
Commercial | Lease Financing
Loans and leases	2,203	2,018
Commercial | Lease Financing | Pass
Loans and leases	2,188	2,012
Commercial | Lease Financing | Special mention
Loans and leases	1	0
Commercial | Lease Financing | Substandard-performing
Loans and leases	12	3
Commercial | Lease Financing | Nonperforming
Loans and leases	2	3
Retail | Residential mortgage
Loans and leases	32,607	31,393
Retail | Residential mortgage | Performing
Loans and leases	32,503	31,274
Retail | Residential mortgage | Nonperforming
Loans and leases	104	119
Retail | Direct
Loans and leases	11,492	11,584
Retail | Direct | Performing
Loans and leases	11,438	11,531
Retail | Direct | Nonperforming
Loans and leases	54	53
Retail | Indirect
Loans and leases	18,209	17,425
Retail | Indirect | Performing
Loans and leases	18,134	17,343
Retail | Indirect | Nonperforming
Loans and leases	$ 75	$ 82