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DEBT SECURITIES - Narrative (Details) - USD ($) $ in Thousands |  | 3 Months Ended |
--- | --- | --- | ---
Jan. 01, 2022 | Mar. 31, 2026 | Mar. 31, 2025 | Dec. 31, 2025
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Debt securities, available-for-sale and held to maturity, accrued interest, after allowance for credit loss |  | $ 19,100 |  | $ 20,200
Debt securities, available-for-sale, accrued interest, after allowance for credit loss |  | 16,700 |  | 17,800
Debt securities, held-to-maturity, accrued interest, after allowance for credit loss |  | 2,100 |  | 2,200
Trading securities |  | 49,463 |  | 49,518
Trading gains (losses) recorded in servicing income |  | (533) | $ 0 |
Tax exempt interest income on available-for-sale securities |  | 4,300 | 770 |
Unrealized loss accreted to interest income |  | 605 | $ 627 |
Debt securities, available-for-sale, transfer to held-to-maturity, gain (loss) |  | 0 |  |
Allowance for credit loss on debt securities, available-for-sale |  | 0 |  |
Allowance for credit loss on debt securities, held-to-maturity |  |  |  | 0
Asset Pledged as Collateral | Federal Reserve Bank Advances | Equity Securities |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Public funds included in deposits, pledged collateral, amount |  | 3,300,000 |  |
Asset Pledged as Collateral | Public, Trust And Bankruptcy Deposits |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Public funds included in deposits, pledged collateral, amount |  | 1,600,000 |  |
Residential and Commercial Portfolio Segment | Residential and Commercial Mortgage |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Transfers of securities available-for-sale to held-to-maturity | $ 1,700,000 |  |  |
Residential and Commercial Portfolio Segment | Residential and Commercial Mortgage | Securities |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Other comprehensive income, amount remaining of debt securities available for sale transfer to held to maturity, before tax | 23,500 |  |  |
Other comprehensive income, amount remaining of debt securities available for sale transfer to held to maturity, net of deferred taxes | $ 16,700 |  |  |
US Treasury Notes Securities |  |  |  |
Debt Securities, Available-for-sale [Line Items] |  |  |  |
Trading securities |  | $ 49,500 |  | $ 49,500

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