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Investment Securities - Additional Information (Detail) | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2024 USD ($) shares | Jun. 30, 2023 USD ($) | Jun. 30, 2024 USD ($) shares | Jun. 30, 2023 USD ($) | Dec. 31, 2023 USD ($)
Debt Securities, Held-to-maturity, Restricted | $ 374,600,000 |  | $ 374,600,000 |  | $ 98,100,000
Debt Securities, Available-for-sale, Restricted | $ 850,900,000 |  | $ 850,900,000 |  | 386,500,000
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total | 187 |  | 187 |  |
Other Investments and Securities, at Cost | $ 6,200,000 |  | $ 6,200,000 |  | 6,200,000
Federal Home Loan Bank Stock | 18,300,000 |  | 18,300,000 |  | 44,700,000
Amortized Cost | 1,194,858,000 |  | 1,194,858,000 |  | 1,138,425,000
Debt Securities, Available-for-Sale | 1,071,161,000 |  | 1,071,161,000 |  | 1,020,986,000
Gain (Loss) on Equity Securities | $ 5,558,000 | $ 0 | $ 5,558,000 | $ 0 |
Expected Class C Visa Shares | shares | 5,294 |  | 5,294 |  |
Expected Class B-2 Shares | shares | 13,340 |  | 13,340 |  |
Sales |  |  |  |  |
Gross Losses |  |  | $ 5,535,000 | 0 |
Gross Gains |  |  | $ 0 | 0 |
US Government-sponsored Enterprises Debt Securities [Member] |  |  |  |  |
Percent of Unrealized Losses | 96.00% |  | 96.00% |  |
Amortized Cost | $ 1,000,000 |  | $ 1,000,000 |  | 1,000,000
Debt Securities, Available-for-Sale | $ 922,000 |  | $ 922,000 |  | $ 915,000
Corporate Debt Securities [Member] |  |  |  |  |
Investment Securities in Unrealized Loss Position, Qualitative Disclosure, Number of Positions, Total | 10 |  | 10 |  | 8
Amortized Cost | $ 67,133,000 |  | $ 67,133,000 |  | $ 51,886,000
Debt Securities, Available-for-Sale | $ 63,291,000 |  | 63,291,000 |  | $ 48,412,000
Equity Securities [Member] |  |  |  |  |
Equity Securities without Readily Determinable Fair Value, Impairment Loss, Annual Amount |  |  | $ 0 | $ 0 |

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