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Note 5 - Investment Securities (Details Textual) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 USD ($) shares | Dec. 31, 2023 USD ($) | Dec. 31, 2022 USD ($)
Debt Securities, Trading | $ 3,309 | $ 0 |
Debt Securities, Held-to-Maturity, Allowance for Credit Loss, Excluding Accrued Interest | 131 | 213 |
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss |  | 1,500 |
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss |  | 1,400 |
Proceeds from Sale of Held-to-Maturity Securities | 0 | 0 | $ 0
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss | 275,716 |  |
Debt Securities, Held-to-Maturity, Nonaccrual, Interest Income | 0 | 0 | 0
Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | $ 962,272 | $ 884,482 |
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] | Interest Receivable | Interest Receivable |
Debt Securities, Held-to-Maturity, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] | Interest Receivable | Interest Receivable |
Debt Securities, Held-to-Maturity, Nonaccrual |  | $ 0 | $ 0
Preferred Class B [Member] | Visa [Member] |  |  |
Investment Owned, Conversion Ratio | 1.5653 |  |
Investment Owned, Balance, Shares (in shares) | shares | 6,924 |  |
Investment, Tax Basis, Cost | $ 0 | 0 |
Preferred Class A [Member] | Visa [Member] |  |  |
Investment Owned, Balance, Shares (in shares) | shares | 10,838 |  |
Asset Pledged as Collateral [Member] | Deposits [Member] |  |  |
Debt Securities, Available-for-Sale and Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss | $ 340,200 | 250,000 |
Financial Asset, Past Due [Member] |  |  |
Debt Securities, Held-to-Maturity, Excluding Accrued Interest, before Allowance for Credit Loss | 0 | $ 0 |
Available-for-sale Investment Securities [Member] |  |  |
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss | 2,000 |  |
Held-to-maturity Investment Securities [Member] |  |  |
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss | $ 1,300 |  |

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