LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 143,667	$ 142,692
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	74,589	73,812
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	50,307	49,232
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	24,282	24,580
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	69,078	68,880
Retail | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	35,404	35,024
Retail | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	19,449	19,069
Retail | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	1,863	2,310
Retail | Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	8,340	8,416
Retail | Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 4,022	$ 4,061