LOANS AND LEASES - Summary of Loans and Leases Portfolio (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 140,870	$ 139,203
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	72,493	69,776
Commercial | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	46,953	42,551
Commercial | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	25,540	27,225
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	68,377	69,427
Retail | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	34,477	32,726
Retail | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	18,415	16,495
Retail | Automobile
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,816	4,744
Retail | Education
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	8,556	10,812
Retail | Other retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 4,113	$ 4,650