Note 10 - Share-based Compensation - Summary of Activity Relating to Company's ESPP Program (Details) - USD ($) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Compensation expense | $ 49,150 | $ 113,531 |
| Shares of stock sold to employees (in shares) | 68,958 | 88,109 |
| Weighted average fair value per ESPP award (in dollars per share) | $ 2.21 | $ 2.73 |
| X | ||||||||||
- Definition The weighted average purchase price of shares purchased under the employee stock purchase plan. No definition available.
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| X | ||||||||||
- Definition The amount of plan compensation cost recognized during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Number of shares issued during the period as a result of an employee stock purchase plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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