LOANS HELD FOR INVESTMENT - Loan Portfolio Held for Investment (Parenthetical) (Details) - USD ($) $ in Thousands |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Loans held for investment | $ 13,091,077 | $ 13,125,356 |
| Unaccreted fair value net purchase discounts | 17,800 | 18,400 |
| Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Loans held for investment | 3,694,843 | 3,688,358 |
| Commercial Portfolio Segment [Member] | Commercial loans secured by real estate [Member] | Commercial and Industrial Sector [Member] | ||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||
| Loans held for investment | $ 871,100 | $ 887,500 |