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Commitments and Contingent Liabilities - Notional Amount of Outstanding Commitments (Detail) - USD ($) $ in Thousands | Sep. 30, 2023 | Dec. 31, 2022
--- | --- | ---
Commitments to extend credit [Member] |  |
Loss Contingencies [Line Items] |  |
Financial instrument of credit risk | $ 2,525,601 | $ 2,356,539
Financial standby letters of credit [Member] |  |
Loss Contingencies [Line Items] |  |
Financial instrument of credit risk | 12,265 | 18,417
Performance standby letters of credit [Member] |  |
Loss Contingencies [Line Items] |  |
Financial instrument of credit risk | 15,801 | 12,853
Commercial letters of credit [Member] |  |
Loss Contingencies [Line Items] |  |
Financial instrument of credit risk | $ 161 | $ 573

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