Loans and ACL - Risk Rating (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Loans and leases	$ 149,013	$ 143,701
Commercial | Commercial & Industrial
Loans and leases	61,935	59,153
Commercial | Commercial & Industrial | Pass
Loans and leases	60,655	57,700
Commercial | Commercial & Industrial | Special mention
Loans and leases	216	268
Commercial | Commercial & Industrial | Substandard-performing
Loans and leases	864	926
Commercial | Commercial & Industrial | Nonperforming
Loans and leases	200	259
Commercial | CRE
Loans and leases	21,060	21,263
Commercial | CRE | Pass
Loans and leases	20,712	20,862
Commercial | CRE | Special mention
Loans and leases	61	48
Commercial | CRE | Substandard-performing
Loans and leases	222	308
Commercial | CRE | Nonperforming
Loans and leases	65	45
Commercial | Lease Financing
Loans and leases	2,018	1,911
Commercial | Lease Financing | Pass
Loans and leases	2,012	1,881
Commercial | Lease Financing | Special mention
Loans and leases	0	6
Commercial | Lease Financing | Substandard-performing
Loans and leases	3	23
Commercial | Lease Financing | Nonperforming
Loans and leases	3	1
Retail | Residential mortgage
Loans and leases	31,393	28,725
Retail | Residential mortgage | Performing
Loans and leases	31,274	28,596
Retail | Residential mortgage | Nonperforming
Loans and leases	119	129
Retail | Direct
Loans and leases	11,584	11,891
Retail | Direct | Performing
Loans and leases	11,531	11,827
Retail | Direct | Nonperforming
Loans and leases	53	64
Retail | Indirect
Loans and leases	17,425	17,235
Retail | Indirect | Performing
Loans and leases	17,343	17,163
Retail | Indirect | Nonperforming
Loans and leases	$ 82	$ 72