COMMITMENTS AND CONTINGENT LIABILITIES - Commitments to Extend Credit (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Commercial and industrial | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Contract amount represents credit risk | $ 53,943 | $ 47,736 |
| Consumer loan portfolio | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Contract amount represents credit risk | 23,763 | 21,659 |
| Commercial real estate | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Contract amount represents credit risk | 6,450 | 4,036 |
| Standby letters of credit and guarantees on industrial revenue bonds | ||
| Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items] | ||
| Contract amount represents credit risk | $ 1,409 | $ 895 |