Quarterly report pursuant to Section 13 or 15(d)

Note 7 - Employee and Director Benefits - Summary of Stock Option Activity (Details)

v3.19.1
Note 7 - Employee and Director Benefits - Summary of Stock Option Activity (Details) - Share-based Payment Arrangement, Option [Member] - USD ($)
 3 Months Ended 12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2018
Dec. 31, 2017
Outstanding, shares (in shares) 1,238,748 1,666,834 1,666,834  
Outstanding, weighted average exercise price (in dollars per share) $ 13.02 $ 10.68 $ 10.68  
Outstanding, weighted average remaining contractual term (Year) 6 years 109 days 5 years 182 days 5 years 73 days 5 years 182 days
Outstanding, aggregate intrinsic value $ 21,318,000 $ 43,978 $ 23,355,000 $ 51,377,000
Granted (in shares) 6,000 10,250    
Granted, weighted average exercise price (in dollars per share) $ 34.09 $ 41.21    
Granted, weighted average remaining contractual term (Year) 9 years 292 days 9 years 328 days    
Granted, aggregate intrinsic value $ (2,000) $ (4,000)    
Exercised (in shares) (162,500) (173,836)    
Exercised, weighted average exercise price (in dollars per share) $ 4.59 $ 4.90    
Exercised, weighted average remaining contractual term (Year) 1 year 255 days 3 years 146 days    
Exercised, aggregate intrinsic value $ 4,384,000 $ 6,244,000    
Forfeited (in shares) (1,000)    
Forfeited, weighted average exercise price (in dollars per share) $ 25.41    
Forfeited, weighted average remaining contractual term (Year) 8 years 182 days    
Forfeited, aggregate intrinsic value $ 15,000    
Outstanding, shares (in shares) 1,082,248 1,502,248 1,238,748 1,666,834
Outstanding, weighted average exercise price (in dollars per share) $ 14.41 $ 11.54 $ 13.02 $ 10.68
Exercisable, shares (in shares) 354,800 672,600    
Exercisable, weighted average exercise price (in dollars per share) $ 8.40 $ 5.48    
Exercisable, weighted average remaining contractual term (Year) 4 years 3 years 328 days    
Exercisable, aggregate intrinsic value $ 9,356,000 $ 23,770,000