Note 8 - Stockholders' Equity (Details Textual) - USD ($) shares in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Payment Arrangement, Expense	$ 125,000	$ 163,000	$ 206,000	$ 300,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period			0

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

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