Note 5 - Stock-based Compensation (Details Textual)	3 Months Ended	6 Months Ended
Jun. 30, 2018 USD ($) shares	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) shares	Jun. 30, 2017 USD ($)
Number of Stock-based Compensation Plans in Effect	3		3
Allocated Share-based Compensation Expense, Total \| $	$ 13,000	$ 14,000	$ 26,000	$ 27,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total \| $	$ 109,000		$ 109,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	12,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	20,000		20,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Total	4,000		4,000

Number of stock-based compensation plans in effect

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Unrecognized cost of unvested share-based compensation awards.

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- Definition

For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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- Definition

Gross number of share options (or share units) granted during the period.

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

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