Note 4 - Accounting for Stock-based Compensation (Details Textual) - USD ($)	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares)	323,000	24,000	323,000	24,000
Share-based Payment Arrangement, Expense	$ 55,000	$ 10,000	$ 74,000	$ 14,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period (in shares)	14,000	14,000	186,600	280,500

Number of share options (or share units) exercised during the current period.

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