Loans and ACL - Risk Rating (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Loans and leases	$ 149,057	$ 149,013
Commercial | Commercial & Industrial
Loans and leases	61,978	61,935
Commercial | Commercial & Industrial | Pass
Loans and leases	60,514	60,655
Commercial | Commercial & Industrial | Special mention
Loans and leases	395	216
Commercial | Commercial & Industrial | Substandard-performing
Loans and leases	873	864
Commercial | Commercial & Industrial | Nonperforming
Loans and leases	196	200
Commercial | CRE
Loans and leases	20,829	21,060
Commercial | CRE | Pass
Loans and leases	20,460	20,712
Commercial | CRE | Special mention
Loans and leases	71	61
Commercial | CRE | Substandard-performing
Loans and leases	223	222
Commercial | CRE | Nonperforming
Loans and leases	75	65
Commercial | Lease Financing
Loans and leases	2,098	2,018
Commercial | Lease Financing | Pass
Loans and leases	2,082	2,012
Commercial | Lease Financing | Special mention
Loans and leases	3	0
Commercial | Lease Financing | Substandard-performing
Loans and leases	12	3
Commercial | Lease Financing | Nonperforming
Loans and leases	1	3
Retail | Residential mortgage
Loans and leases	31,572	31,393
Retail | Residential mortgage | Performing
Loans and leases	31,451	31,274
Retail | Residential mortgage | Nonperforming
Loans and leases	121	119
Retail | Direct
Loans and leases	11,464	11,584
Retail | Direct | Performing
Loans and leases	11,411	11,531
Retail | Direct | Nonperforming
Loans and leases	53	53
Retail | Indirect
Loans and leases	17,523	17,425
Retail | Indirect | Performing
Loans and leases	17,443	17,343
Retail | Indirect | Nonperforming
Loans and leases	$ 80	$ 82