| Note 5 - Capital Stock, Stock Plans and Stock-based Compensation - Stock-based Compensation Recognized (Details) - USD ($) | 3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
| Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015 | |
| Employee Stock Option [Member] | ||||
| Allocated stock-based compensation | $ 12,000 | $ 13,000 | $ 42,000 | $ 39,000 | 
| Director Stock Options [Member] | ||||
| Allocated stock-based compensation | 13,000 | 2,000 | 27,000 | 23,000 | 
| Allocated stock-based compensation | $ 25,000 | $ 15,000 | $ 69,000 | $ 62,000 | 
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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