Quarterly report pursuant to Section 13 or 15(d)

Note 10 - Stock-based Compensation - Stock Options Activity (Details)

v3.19.3
Note 10 - Stock-based Compensation - Stock Options Activity (Details) - Share-based Payment Arrangement, Option [Member] - $ / shares
 9 Months Ended 12 Months Ended
Sep. 30, 2019
Dec. 31, 2018
Dec. 31, 2017
Outstanding, Number of Shares (in shares) 986,691 1,003,916  
Outstanding, Weighted Average Exercise Price (in dollars per share) $ 4.72 $ 4.18  
Outstanding, Weighted Average Remaining Contractual Life (Year) 6 years 292 days 6 years 292 days 8 years 36 days
Granted, Number of Shares (in shares) 65,759 145,792  
Granted, Weighted Average Exercise Price (in dollars per share) $ 12.31 $ 7  
Exercised, Number of Shares (in shares) (99,132) (95,162)  
Exercised, Weighted Average Exercise Price (in dollars per share) $ 5.32 $ 3.48  
Cancelled, Number of Shares (in shares) (67,855)  
Cancelled, Weighted Average Exercise Price (in dollars per share) $ 3.37  
Outstanding, Number of Shares (in shares) 953,318 986,691 1,003,916
Outstanding, Weighted Average Exercise Price (in dollars per share) $ 5.19 $ 4.72 $ 4.18
Exercisable, Number of Shares (in shares) 557,588    
Exercisable, Weighted Average Exercise Price (in dollars per share) $ 4.48    
Exercisable, Weighted Average Remaining Contractual Life (Year) 6 years 36 days