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Employee Benefits and Stock Compensation - Additional Information (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
May 24, 2018
Aug. 26, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Defined contribution plan charges to operations $ 2.1 $ 1.9 $ 1.7    
Number of shares authorized for issuance (in shares)       4,250,000 3,000,000
Number of shares authorized for repurchase (in shares) 300,000        
Percent of fair market value that employees may purchase shares 95.00%        
2013 Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Remaining shares authorized for issuance (in shares) 1,256,000        
Stock Option          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period 5 years        
Maximum term 10 years        
Restricted Stock          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period 3 years        
Restricted Stock Units          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period 3 years        
Restricted Stock Units | Minimum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Target award percentage 0.00% 0.00% 0.00%    
Restricted Stock Units | Maximum          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Target award percentage 200.00% 200.00% 200.00%