LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 137,635	$ 139,203
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	70,508	69,776
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	43,781	42,551
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	26,727	27,225
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	67,127	69,427
Retail | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	33,114	32,726
Retail | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	16,853	16,495
Retail | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,044	4,744
Retail | Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	8,779	10,812
Retail | Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 4,337	$ 4,650