Note 4 - Earnings Per Share (Details Textual) - $ / shares	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance	18,250	27,762	19,750
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Lower Range Limit	$ 17.55	$ 17.55
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Upper Range Limit	$ 23	$ 37.48
Employee Stock Option and Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance	14,601	15,800	14,601

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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