LOANS AND LEASES - Schedule of Amortized Cost of Loans (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Total net unamortized discount | $ 1,281 | $ 1,326 |
| Non-PCD | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Deferred fees, including unamortized costs and unearned fees on non-PCD loans | (102) | (103) |
| Total net unamortized discount | 1,238 | 1,281 |
| PCD | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Total net unamortized discount | $ 43 | $ 45 |