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Note 6 - Borrowings and Subordinated Notes (Details Textual) - USD ($) |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Apr. 14, 2021 | Dec. 31, 2020 | Sep. 30, 2023 | Dec. 31, 2022
Federal Home Loan Bank Advances [Member] |  |  |  |
Debt, Long-term and Short-term, Combined Amount, Total |  |  | $ 0 | $ 0
Line of Credit [Member] | Unsecured Debt [Member] |  |  |  |
Line of Credit, Current |  | $ 5,000,000.0 |  |
Debt Instrument, Prime Rate Floor |  | 2.40% |  |
Prime Rate [Member] | Line of Credit [Member] | Unsecured Debt [Member] |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  | 0.50% |  |
The 3.75 Percent Fixed-to-Floating Rate Subordinated Notes [Member] |  |  |  |
Debt Instrument, Face Amount | $ 20,000,000.0 |  |  |
Debt Instrument, Interest Rate, Stated Percentage | 3.75% |  |  |
Debt Issuance Costs, Net, Total | $ 441,000 |  | $ 333,000 | $ 366,000
Debt Instrument, Term (Year) | 10 years |  |  |
The 3.75 Percent Fixed-to-Floating Rate Subordinated Notes [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] |  |  |  |
Debt Instrument, Basis Spread on Variable Rate | 2.99% |  |  |

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