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Note 5 - Allowance for Loan Losses, Nonperforming Assets and Impaired Loans (Details Textual) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2015 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014
Threshold Period for Considering Loans as Special Mention or Classified |  | 75 days |  |  |
Allowance for Credit Losses, Change in Method of Calculating Impairment | $ 0 | $ 0 | $ 0 | $ 0 |
Financing Receivable, Modifications, Number of Contracts |  | 10 | 4 | 6 |
Financing Receivable, Modifications, Subsequent Default, Number of Contracts |  | 0 | 0 | 0 |
Interest and Fee Income, Loans and Leases |  | $ 29,932 | $ 29,365 | $ 30,446 |
Nonperforming Financial Instruments [Member] |  |  |  |  |
Interest and Fee Income, Loans and Leases |  | $ 0 | $ 0 | $ 0 |
Construction Loans [Member] | Become Non-Revolving and Interest Only Payments [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts | 2 |  |  |  |
Commercial Non Real Estate Segment [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  |  | 1 |  |
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  | 4 | 1 | 1 |
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] | Interest Method Changed from Variable to Fixed [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  | 1 |  |  |
Commercial Non Real Estate Segment [Member] | Commercial and Industrial [Member] | Contractual Interest Rate Reduction [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  | 3 |  |  |
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] |  |  |  |  |
Allowance for Credit Losses, Change in Method of Calculating Impairment |  | $ 1 |  |  |
Financing Receivable, Modifications, Number of Contracts |  | 4 | 1 |  |
Consumer Non Real Estate Portfolio Segment [Member] | Automobile Loan [Member] | Principal Forgiveness [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  | 1 |  |  |
Commercial Real Estate Portfolio Segment [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  |  |  |  | 2
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] |  |  |  |  |
Financing Receivable, Modifications, Number of Contracts |  |  |  | 3 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] | Forgive Principal, Reduce Interest Rate, Capitalize Interest, and Re-amortize Payments [Member] |  |  |  |  |
Allowance for Credit Losses, Change in Method of Calculating Impairment | $ 0 |  |  | $ 0 |
Financing Receivable Modifications Principal Forgiven |  |  |  | 100 |
Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate, Owner Occupied [Member] | Interest Only Payments [Member] |  |  |  |  |
Allowance for Credit Losses, Change in Method of Calculating Impairment | $ 23 |  |  | 23 |
Financing Receivable, Modifications, Number of Contracts | 2 |  |  |  |
Commercial Portfolio Segment [Member] | Extended Maturity [Member] |  |  |  |  |
Allowance for Credit Losses, Change in Method of Calculating Impairment | $ 0 |  |  | $ 0 |
Financing Receivable, Modifications, Number of Contracts | 1 |  |  |  |
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% |  |  |

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- Definition The aggregate interest and fee income generated by: (1) loans the Entity has positive intent and ability to hold for the foreseeable future, or until maturity or payoff, including commercial and consumer loans, whether domestic or foreign, which may consist of: (a) industrial and agricultural; (b) real estate; and (c) real estate construction loans; (d) trade financing; (e) lease financing; (f) home equity lines-of-credit; (g) automobile and other vehicle loans; and (h) credit card and other revolving-type loans and (2) loans and leases held-for-sale which may include mortgage loans, direct financing, and sales-type leases. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.1) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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