Quarterly report pursuant to Section 13 or 15(d)

Note 9 - Equity - Stock Options Activity (Details)

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Note 9 - Equity - Stock Options Activity (Details) - $ / shares
 3 Months Ended 12 Months Ended
Mar. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Granted at Market Price, Number of Shares (in shares) 60,000    
Employee Stock Option [Member]      
Outstanding, Number of Shares (in shares) 1,003,916 953,075  
Outstanding, Weighted Average Exercise Price (in dollars per share) $ 4.18 $ 3.66  
Outstanding, Weighted Average Fair Value (in dollars per share) $ 1.93 $ 1.87 $ 1.86
Outstanding, Weighted Average Remaining Contractual Life (Year) 8 years 8 years 36 days 6 years 328 days
Granted at Market Price, Number of Shares (in shares) 60,000 295,286  
Granted at Market Price, Weighted Average Exercise Price (in dollars per share) $ 5.89 $ 4.31  
Exercised, Number of Shares (in shares) (7,500) (206,875)  
Exercised, Weighted Average Exercise Price (in dollars per share) $ 3.11 $ 1.76  
Cancelled, Number of Shares (in shares) (2,605) (37,570)  
Cancelled, Weighted Average Exercise Price (in dollars per share) $ 5.03 $ 5.11  
Outstanding, Number of Shares (in shares) 1,053,811 1,003,916 953,075
Outstanding, Weighted Average Exercise Price (in dollars per share) $ 4.29 $ 4.18 $ 3.66
Exercisable, Number of Shares (in shares) 476,601    
Exercisable, Weighted Average Exercise Price (in dollars per share) $ 4.77    
Exercisable, Weighted Average Fair Value (in dollars per share) $ 2.07    
Exercisable, Weighted Average Remaining Contractual Life (Year) 7 years 219 days