Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Employee and Director Benefits - Summary of Stock Option Activity (Details)

v3.10.0.1
Note 6 - Employee and Director Benefits - Summary of Stock Option Activity (Details) - Employee Stock Option [Member] - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended 12 Months Ended
Mar. 31, 2017
Jun. 30, 2018
Dec. 31, 2017
Dec. 31, 2016
Outstanding, shares (in shares) 2,026,334 1,666,834 2,026,334  
Outstanding, weighted average exercise price (in dollars per share) $ 9 $ 10.68 $ 9  
Outstanding, weighted average remaining contractual term (Year) 5 years 328 days 5 years 109 days 5 years 182 days 6 years 73 days
Outstanding, aggregate intrinsic value $ 45,777 $ 43,787 $ 51,377 $ 57,636
Granted (in shares) 51,500 12,750    
Granted, weighted average exercise price (in dollars per share) $ 37.95 $ 41.50    
Granted, weighted average remaining contractual term (Year) 9 years 219 days 9 years 255 days    
Granted, aggregate intrinsic value $ (80) $ (9)    
Exercised (in shares) (292,000) (175,836)    
Exercised, weighted average exercise price (in dollars per share) $ 4.98 $ 4.90    
Exercised, weighted average remaining contractual term (Year) 4 years 146 days 3 years 36 days    
Exercised, aggregate intrinsic value $ 9,169 $ 6,317    
Forfeited (in shares) (32,000) (6,000)    
Forfeited, weighted average exercise price (in dollars per share) $ 21.96 $ 19.50    
Forfeited, weighted average remaining contractual term (Year) 8 years 219 days 7 years 255 days    
Forfeited, aggregate intrinsic value $ (462) $ 128    
Outstanding, shares (in shares) 1,753,834 1,497,748 1,666,834 2,026,334
Outstanding, weighted average exercise price (in dollars per share) $ 10.28 $ 11.58 $ 10.68 $ 9
Exercisable, shares (in shares) 811,736 748,600    
Exercisable, weighted average exercise price (in dollars per share) $ 5.20 $ 7.34    
Exercisable, weighted average remaining contractual term (Year) 4 years 146 days 3 years 328 days    
Exercisable, aggregate intrinsic value $ 25,303 $ 25,811