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Note 1 - Summary of Significant Accounting Policies (Details Textual) $ in Thousands | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) | Jun. 01, 2014 USD ($)
Number of Unconsolidated Business Trusts Formed to Issue Trust Preferred Securities | 5 |  |
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Ending Balance | $ 0 |  |
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss | 3,600 | $ 2,600 |
Financing Receivable, Unamortized Loan Cost (Fee) | $ 2,200 | 2,400 |
Interest Income on Commercial and Mortgage Loans Discontinued Period (Day) | 90 days |  |
Maximum Delinquency Period for Consumer and Credit Card Loans to be Charged Off (Day) | 120 days |  |
Financing Receivable, Accrued Interest, after Allowance for Credit Loss | $ 17,300 | 16,900 |
Repossessed Assets | $ 200 |  |
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] | Other Assets |  |
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] | Other Assets |  |
Not Designated as Hedging Instrument [Member] | Mortgage Loan Derivative [Member] |  |  |
Derivative Asset | $ 100 |  |
Derivative Liability |  | 100 |
Commercial Loan [Member] |  |  |
Loan Participation, Amount | $ 48,600 | $ 46,700 |
Firstbank Corporation [Member] |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets, Total |  |  | $ 1,500,000
Business Combination Branches Acquired |  |  | 46

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