Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Narratives (Details)

v3.19.1
Stock-Based Compensation - Narratives (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based compensation expense $ 3,400 $ 3,831
Number of shares available for grant 3,666,886  
Restricted Stock Units (RSUs)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Unrecognized share-based compensation expense $ 29,715  
Unrecognized share-based compensation expense, period for recognition 2 years 1 month 2 days  
Restricted Stock Units (RSUs) | Director    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Award vesting period 1 year  
Restricted Stock Units (RSUs) | Employee    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Award vesting period 3 years  
Performance Stock Units (PSUs)    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Award vesting period 3 years  
Unrecognized share-based compensation expense $ 8,159  
Unrecognized share-based compensation expense, period for recognition 2 years 11 months 1 day  
Performance Stock Units (PSUs) | Minimum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Award vesting percentage 0.00%  
Performance Stock Units (PSUs) | Maximum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Award vesting percentage 200.00%