Annual report pursuant to Section 13 and 15(d)

Note 5 - Stock-based Compensation - Summary of Stock Option Activity (Details)

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Note 5 - Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Outstanding at beginning of year (in shares) 3,380,615    
Outstanding at beginning of year (in dollars per share) $ 2    
Granted (in shares) 1,720,000    
Granted, weighted average exercise price (in dollars per share) $ 0.71    
Exercised (in shares) (50,000) (50,000) (146,625)
Exercised, weighted average exercise price (in dollars per share) $ 0.36    
Canceled and forfeited (in shares) (1,362,936)    
Canceled and Forfeited, weighted average exercise price (in dollars per share) $ 1.77    
Outstanding at end of year (in shares) 3,687,679 3,380,615  
Outstanding at end of year (in dollars per share) $ 1.50 $ 2  
Outstanding at end of year (Year) 7 years    
Outstanding at end of year    
Exercisable at end of year (in shares) 1,946,445    
Exercisable at end of year (in dollars per share) $ 2.15    
Exercisable at end of year (Year) 4 years 328 days    
Exercisable at end of year