Note 10 - Earnings Per Share (Details Textual) - shares	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance	387,930	384,730
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number	227,930	124,730
Employee Stock Option [Member]
Incremental Common Shares Attributable to Share-based Payment Arrangements, Total	10,447	32,286
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	365,000	325,000

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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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 number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Number of options outstanding, including both vested and non-vested options.

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