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Securities - Schedule of Other Securities (Detail) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
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Schedule of Other Securities [Line Items] |  |
Other securities | $ 719,575 | $ 471,018
FRB and FHLB stock [Member] |  |
Schedule of Other Securities [Line Items] |  |
Other securities | 137,406 | 42,672
Equity Securities With Readily Determinable Fair Values [Member] |  |
Schedule of Other Securities [Line Items] |  |
Other securities | 41,150 | 11,596
Equity Securities Without Readily Determinable Fair Values [Member] |  |
Schedule of Other Securities [Line Items] |  |
Other securities | $ 541,019 | $ 416,750

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