LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 147,491	$ 142,692
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	77,284	73,812
Commercial \| Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	53,467	49,232
Commercial \| Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	23,817	24,580
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	70,207	68,880
Retail \| Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	36,374	35,024
Retail \| Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	20,276	19,069
Retail \| Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	1,482	2,310
Retail \| Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	8,044	8,416
Retail \| Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 4,031	$ 4,061