LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 145,959	$ 156,662
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	74,445	82,180
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	43,826	51,836
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	29,471	28,865
Commercial | Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	1,148	1,479
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	71,514	74,482
Retail | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	31,332	29,921
Retail | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	15,040	14,043
Retail | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	8,258	12,292
Retail | Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	11,834	12,808
Retail | Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 5,050	$ 5,418