Annual report pursuant to Section 13 and 15(d)

Stock Options, Stock Grants and New Stock Issues - Summary of Stock Option Activity (Details)

v3.19.1
Stock Options, Stock Grants and New Stock Issues - Summary of Stock Option Activity (Details) - USD ($)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]        
Outstanding, beginning of year, weighted average exercise price (dollars per share) $ 12.96 $ 12.77 $ 12.79  
Exercised, weighted average exercise price (dollars per share) 12.09 11.55    
Expired, weighted average exercise price (dollars per share) 16.01 15.26 16.01  
Outstanding, end of year, weighted average exercise price (dollars per share) 14.16 $ 12.96 $ 12.77 $ 12.79
Exercisable, weighted average exercise price (dollars per share) $ 13.82      
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]        
Outstanding, beginning of year (shares) 145,511 173,048 173,985  
Exercised (shares) (85,440) (25,632)    
Expired (shares) (975) (1,905) (937)  
Outstanding, end of year (shares) 59,096 145,511 173,048 173,985
Exercisable (shares) 49,127      
Options outstanding, weighted average contractual term 4 years 9 months 18 days 4 years 7 months 6 days 5 years 4 months 24 days 6 years 4 months 24 days
Options exercisable, weighted average contractual term 4 years 6 months      
Options outstanding, intrinsic value $ 143,737 $ 156,445 $ 0 $ 0
Options expired, intrinsic value 842,742 $ 78,818    
Options exercisable, intrinsic value $ 136,123      
Options available (shares) 155,845 154,870 152,965 152,028
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest [Roll Forward]        
Expected to vest, beginning of the year, weighted average exercise price (dollars per share) $ 14.72 $ 14.72    
Vested, weighted average exercise price (dollars per share) 14.78 14.35    
Forfeited, weighted average exercise price (dollars per share) 16.01 15.38    
Expected to vest, end of the year, weighted average exercise price (dollars per share) $ 15.83 $ 14.72 $ 14.72  
Expected to vest (shares) 25,650 43,286    
Vested (shares) (15,380) (17,574)    
Forfeited unvested options (shares) (301) (62)    
Expected to vest (shares) 9,969 25,650 43,286  
Options expected to vest, weighted average contractual term (years) 6 years 6 years 6 months 7 years 1 month 6 days  
Options expected to vest, grant date fair value (dollars per share) $ 6.44 $ 6.41 $ 6.24  
Options expected to vest, vested, grant date fair value (dollars per share) $ 6.38 $ 5.96