Quarterly report pursuant to Section 13 or 15(d)

Stock options and restricted stock (Details)

v3.19.1
Stock options and restricted stock (Details) - USD ($)
3 Months Ended 12 Months Ended
Feb. 08, 2019
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Allocated share-based compensation expense   $ 615,739 $ 192,201  
Antidilutive securities excluded from computation of earnings per share, amount (in shares)     117,879  
Stock Options        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Options exercised (in shares)   0 0  
Performance Shares | 2016 Performance Stock Awards Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period       3 years
Equity instruments other options, grants in period (in shares) 46,477      
Equity instruments other than options, grants in period, weighted average grant date fair value (in dollars per share) $ 8.05      
Performance Shares | 2016 Performance Stock Awards Plan | Minimum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Percentage of target award       0.00%
Performance Shares | 2016 Performance Stock Awards Plan | Maximum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Percentage of target award       150.00%
Stock Awards | 2015 Stock Awards Plan        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Equity instruments other options, grants in period (in shares) 44,949      
Equity instruments other than options, grants in period, weighted average grant date fair value (in dollars per share) $ 15.72      
Period after option grant before options can be exercised (in years) 1 year      
Stock Awards | 2015 Stock Awards Plan | Minimum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Annual vesting rate (percent) 20.00%      
Stock Awards | 2015 Stock Awards Plan | Maximum        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Annual vesting rate (percent) 33.00%