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Securities - Schedule of Other Securities (Detail) - USD ($) $ in Thousands | Mar. 31, 2026 | Dec. 31, 2025
--- | --- | ---
Schedule of Other Securities [Line Items] |  |
Other securities | $ 685,590 | $ 676,300
FRB and FHLB stock [Member] |  |
Schedule of Other Securities [Line Items] |  |
Other securities | 137,660 | 137,498
Equity Securities With Readily Determinable Fair Values [Member] |  |
Schedule of Other Securities [Line Items] |  |
Other securities | 12,604 | 14,690
Equity Securities Without Readily Determinable Fair Values [Member] |  |
Schedule of Other Securities [Line Items] |  |
Other securities | $ 535,326 | $ 524,112

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