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Stock Plans and Stock-Based Compensation - Performance-Based Restricted Stock Units - Additional Information (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Stock-based compensation expense $ 8,301 $ 3,541 $ 24,094 $ 20,257
Performance-Based Restricted Stock Units        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Share-based compensation, number of stock unit grants in period     328,343  
Stock-based compensation expense 3,100 $ 200 $ 6,700 $ 400
Unrecognized compensation expense $ 31,800   $ 31,800  
Weighted-average amortization period     2 years 1 month 20 days  
Number of stock units vested     0  
Performance-Based Restricted Stock Units | Tranche One        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Share-based compensation, compounded annual growth measurement period     2 years  
Share-based compensation, vesting stock percentage     50.00%  
Performance-Based Restricted Stock Units | Tranche Two        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Share-based compensation, compounded annual growth measurement period     3 years  
Performance-Based Restricted Stock Units | Minimum        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Share-based compensation, thresholds percentage of revenue growth     20.00%  
Share price $ 54.83   $ 54.83  
Performance-Based Restricted Stock Units | Maximum        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Share-based compensation, thresholds percentage of revenue growth     40.00%  
Share price $ 98.92   $ 98.92