Note K - Stock-based Compensation - Schedule of Stock Option Activity (Details) - USD ($)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Outstanding, number of options (in shares) 1,397,511    
Outstanding, weighted average exercise price (in dollars per share) $ 13.28    
Outstanding, weighted average remaining contractual term (Year) 8 years 98 days 8 years 211 days  
Outstanding, aggregate intrinsic value $ 26,400 $ 9,204,403  
Granted (in shares) 959,375    
Granted (in dollars per share) $ 13.31    
Exercised (in shares) (14,933) (4,766) 0
Exercised (in dollars per share) $ 4.78    
Canceled, forfeited or expired (in shares) (351,693)    
Canceled, forfeited or expired (in dollars per share) $ 11.65    
Outstanding, number of options (in shares) 1,990,260 1,397,511  
Outstanding, weighted average exercise price (in dollars per share) $ 13.64 $ 13.28  
Exercisable, number of options (in shares) 637,492    
Exercisable, weighted average exercise price (in dollars per share) $ 10.77    
Exercisable, weighted average remaining contractual term (Year) 6 years 284 days    
Exercisable, aggregate intrinsic value $ 26,400    
Vested and expected to vest, number of options (in shares) 1,978,260    
Vested and expected to vest, weighted average exercise price (in dollars per share) $ 13.62    
Vested and expected to vest, weighted average remaining contractual term (Year) 8 years 98 days    
Vested and expected to vest, aggregate intrinsic value $ 26,400