Note 4 - Stock-based Compensation (Details Textual) shares in Thousands	3 Months Ended
Mar. 31, 2018 USD ($) shares	Mar. 31, 2017 USD ($)
Number of Stock-based Compensation Plans in Effect	3
Allocated Share-based Compensation Expense, Total	$ 13,000	$ 13,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Total	$ 64,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross \| shares	0

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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-Paragraph 1
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-Subparagraph (h)(1)(i)
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