Note 4 - Earnings Per Share - Shares Used in Calculation of Earnings Per Share (Details) - shares	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Weighted-average common shares issued (in shares)	7,298,740	7,270,608
Average treasury stock shares (in shares)	(881,631)	(772,330)
Weighted-average common shares and common stock equivalents used to calculate basic earnings per share (in shares)	6,417,109	6,498,278
Additional common stock equivalents (stock options and restricted stock) used to calculate diluted earnings per share (in shares)	12,334	12,290
Weighted-average common shares and common stock equivalents used to calculate diluted earnings per share (in shares)	6,429,443	6,510,568

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.

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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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This element represents the weighted average total number of shares issued throughout the period including the first (beginning balance outstanding) and last (ending balance outstanding) day of the period before considering any reductions (for instance, shares held in treasury) to arrive at the weighted average number of shares outstanding. Weighted average relates to the portion of time within a reporting period that common shares have been issued and outstanding to the total time in that period. Such concept is used in determining the weighted average number of shares outstanding for purposes of calculating earnings per share (basic).

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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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Number of shares of treasury stock determined by relating the portion of time within a reporting period that treasury shares have been outstanding to the total time in that period. Treasury stock is stock that the Entity has issued but subsequently reacquired.

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