LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 149,746	$ 156,662
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	77,457	82,180
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	46,753	51,836
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	29,486	28,865
Commercial | Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	1,218	1,479
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	72,289	74,482
Retail | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	30,983	29,921
Retail | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	14,729	14,043
Retail | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	9,290	12,292
Retail | Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	12,134	12,808
Retail | Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 5,153	$ 5,418