Annual report pursuant to Section 13 and 15(d)

Equity Compensation - Narrative (Details)

v3.19.3.a.u2
Equity Compensation - Narrative (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award        
Period of options granted (in years) 5 years      
Equity-based compensation expense $ 3,843,000 $ 3,098,000 $ 2,598,000  
Stock Option        
Share-based Compensation Arrangement by Share-based Payment Award        
Options outstanding (in shares) 1,116,045 1,327,919 1,506,604 1,539,017
Share price (in usd per share) $ 27.95 $ 30.45 $ 36.06  
Weighted average fair value of options vested (in usd per share) $ 15.91 $ 16.54 $ 12.39  
Total fair value of options that vested during the year $ 1,600,000 $ 1,400,000 $ 1,600,000  
Total compensation costs related to non-vested awards $ 5,200,000      
Weighted average period (in years) 2 years 4 months 2 days      
Weighted average fair value of options granted (in usd per share) $ 11.93 $ 14.64 $ 15.30  
Restricted Stock Units (RSUs)        
Share-based Compensation Arrangement by Share-based Payment Award        
Period of options granted (in years)   3 years    
Total compensation costs related to non-vested awards   $ 2,200,000    
Weighted average period (in years)   2 years    
Number of awards granted in period (in shares)   87,634    
Weighted-average price of awards (in usd per share)   $ 36.01    
Number of awards vested in period (in shares)   17,776    
Equity-based compensation expense   $ 1,600,000    
Employee Stock        
Share-based Compensation Arrangement by Share-based Payment Award        
Share price (in usd per share) $ 24.75      
Cash compensation limit $ 25,000      
Common stock price to market value (percentage) 85.00%      
Number of shares employees had subscribed to purchase (in shares) 133,979      
Weighted average fair value of options granted (in usd per share) $ 8.26 $ 8.48 $ 5.15  
Stock Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award        
Stock option exercisable period (not exceeding, in years) 10 years      
Period of options granted (in years) 5 years      
Options outstanding (in shares) 603,184      
Directors Stock Option Plan        
Share-based Compensation Arrangement by Share-based Payment Award        
Stock option exercisable period (not exceeding, in years) 10 years      
Period of options granted (in years) 6 months      
Options outstanding (in shares) 177,080      
Long Term Incentive Plan        
Share-based Compensation Arrangement by Share-based Payment Award        
Options outstanding (in shares) 453,733      
Options available for future grant (in shares) 1,305,613      
Director        
Share-based Compensation Arrangement by Share-based Payment Award        
Period of options granted (in years) 6 months      
Key Employee        
Share-based Compensation Arrangement by Share-based Payment Award        
Period of options granted (in years) 5 years      
Key Employee | Restricted Stock Units (RSUs)        
Share-based Compensation Arrangement by Share-based Payment Award        
Period of options granted (in years) 3 years      
Maximum        
Share-based Compensation Arrangement by Share-based Payment Award        
Stock option exercisable period (not exceeding, in years) 10 years