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Securities - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 | Dec. 31, 2021 | Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items] |  |  |
Realized gains on sales | $ 22.0 | $ 9.3 |
Investments pledged, carrying value | 255.8 |  | $ 134.8
Investments pledged, carrying par value | 30.0 |  |
Federal Reserve's Bank Term Funding Program [Member] |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |
Investments pledged, carrying value | 61.7 |  |
Investments pledged, carrying par value | $ 69.9 |  |

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