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Note 3 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans (Details Textual) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2018 USD ($) | Sep. 30, 2017 USD ($) | Sep. 30, 2018 USD ($) | Sep. 30, 2017 USD ($) | Dec. 31, 2017 USD ($)
Threshold for Designation to Impaired Status |  |  | $ 250 |  |
Interest and Fee Income, Loans and Leases, Total | $ 8,005 | $ 7,473 | $ 23,159 | $ 22,379 |
Threshold Period for Considering Loans as Special Mention or Classified |  |  | 75 days |  |
Financing Receivable, Reclassification to Held-for-sale |  |  | $ 0 |  |
Financing Receivable, Modifications, Recorded Investment | $ 10,700 | $ 7,964 | $ 10,700 | $ 7,964 | $ 7,897
Financing Receivable, Modifications, Number of Contracts | 2 | 4 | 6 | 7 |
Allowance for Credit Losses, Change in Method of Calculating Impairment | $ 0 | $ 0 | $ 0 | $ 0 |
Financing Receivable, Modifications, Subsequent Default, Number of Contracts |  |  | 0 | 0 |
Residential Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts | 2 |  | 2 |  |
Residential Portfolio Segment [Member] | Investor Owned Residential Real Estate [Member] | Interest Only Payments [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts | 1 |  | 1 |  |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  |  | 2 | 1 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] | Interest Only Payments [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  |  | 2 |  |
Commercial Non Real Estate Segment [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  | 2 |  | 4 |
Commercial Non Real Estate Segment [Member] | Contractual Interest Rate Reduction [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  |  |  | 3 |
Commercial Non Real Estate Segment [Member] | Interest Method Changed from Variable to Fixed [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  |  |  | 1 |
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  | 2 |  | 2 |
Special Mention [Member] |  |  |  |  |
Increase in Percentage of Allocation Loans Rated Special Mention |  |  | 50.00% |  |
Classified Excluding Impaired [Member] |  |  |  |  |
Increase in Percentage of Allocation Loans Rated Classified |  |  | 100.00% |  |
Nonperforming Financial Instruments [Member] |  |  |  |  |
Interest and Fee Income, Loans and Leases, Total |  |  | $ 0 | $ 0 | $ 0

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