LOANS AND LEASES - Nonaccrual Loans by Loan Class (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans and leases with no ACL	$ 229	$ 166
Total nonaccrual loans and leases	1,589	931
Commercial \| Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans and leases with no ACL	196	76
Total nonaccrual loans and leases	986	562
Commercial \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans and leases with no ACL	27	81
Total nonaccrual loans and leases	243	133
Commercial \| Lease financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans and leases with no ACL	2	4
Total nonaccrual loans and leases	8	8
Consumer \| Residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans and leases with no ACL	4	5
Total nonaccrual loans and leases	223	107
Consumer \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans and leases with no ACL	0	0
Total nonaccrual loans and leases	7	6
Consumer \| Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans and leases with no ACL	0	0
Total nonaccrual loans and leases	120	113
Consumer \| RV and marine
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual loans and leases with no ACL	0	0
Total nonaccrual loans and leases	$ 2	$ 2