Note 8 - Earnings Per Share - Calculation of Basic and Diluted Weighted Average Common Shares (Details) - shares	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Weighted average common shares outstanding basic earnings per share (in shares)	6,640,272	6,562,141
Effect of potential common share issuance:
Stock options (in shares)
Weighted average common shares outstanding
Diluted earnings per share (in shares)	6,640,272	6,562,141

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
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-Section 45
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-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1707-109256

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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