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INVESTMENT SECURITIES - Narrative (Details) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022 | Jan. 01, 2021
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Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items] |  |  |
Accrued interest on investment securities | $ 23,200 | $ 29,500 |
Allowance for credit losses | 245 | 245 |
Carrying value of securities pledged as collateral | 1,700,000 | 941,300 |
Securities sold under repurchase agreements | 187,300 | 196,700 |
State and municipal |  |  |
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items] |  |  |
Allowance for credit losses | $ 245 | $ 245 |
State and municipal | CECL adoption |  |  |
Schedule Of Available For Sale Securities And Held To Maturity Securities [Line Items] |  |  |
Allowance for credit losses |  |  | $ 245

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