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Note 1 - Basis of Presentation and Summary of Significant Accounting Policies (Details Textual) |  | 12 Months Ended
--- | --- | ---
Jan. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) $ / shares | Dec. 31, 2022 USD ($) $ / shares | Dec. 31, 2021 USD ($) $ / shares
Number of Bank Branches |  | 27 |  |
Number of Operating Segments |  | 2 |  |
Earnings Per Share, Basic (in dollars per share) | $ / shares |  | $ 4.63 | $ 3.75 | $ 4.48
Earnings Per Share, Diluted (in dollars per share) | $ / shares |  | $ 4.56 | $ 3.7 | $ 4.37
Cash, Uninsured Amount |  | $ 27,000 | $ 281,000 |
Federal Home Loan Bank Stock |  | 2,114,000 | 10,611,000 |
FHLB Impairment |  | 0 | 0 | $ 0
Marketing and Advertising Expense |  | 1,349,000 | 897,000 | 634,000
Goodwill, Impairment Loss |  | $ 0 | 0 | $ 0
Maximum [Member] |  |  |  |
Finite-Lived Intangible Asset, Useful Life (Year) |  | 10 years |  |
Minimum [Member] |  |  |  |
Finite-Lived Intangible Asset, Useful Life (Year) |  | 7 years |  |
Building and Building Improvements [Member] | Maximum [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) |  | 25 years |  |
Furniture Fixtures and Equipment [Member] | Maximum [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) |  | 10 years |  |
Furniture Fixtures and Equipment [Member] | Minimum [Member] |  |  |  |
Property, Plant and Equipment, Useful Life (Year) |  | 3 years |  |
Previously Reported [Member] |  |  |  |
Earnings Per Share, Basic (in dollars per share) | $ / shares |  |  |  | $ 4.42
Earnings Per Share, Diluted (in dollars per share) | $ / shares |  |  |  | $ 4.32
Mortgage Servicing Rights [Member] |  |  |  |
Servicing Asset |  | $ 9,090,000 | $ 18,017,000 |
Subsequent Event [Member] | Mortgage Servicing Rights [Member] |  |  |  |
Servicing Asset | $ 1,290,000,000 |  |  |
Servicing Asset at Fair Value, Disposals | 16,600,000 |  |  |
Servicing Asset at Amortized Cost, Disposals | $ 8,100,000 |  |  |
Servicing Assets Sold, Percent of Portfolio | 45.60% |  |  |

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