XML 88 R77.htm IDEA: XBRL DOCUMENT v3.21.2
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 12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]          
Stock-based compensation expense $ 17,441 $ 13,351 $ 45,631 $ 34,939  
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     323,601    
Stock-based compensation expense 8,100 $ 6,400 $ 21,300 $ 16,100  
Award achievement probability percentage     100.00%    
Weighted-average grant date fair values of units granted     $ 124.45 $ 120.11  
Number of stock units vested     59,200    
Unrecognized compensation expense $ 43,800   $ 43,800    
Weighted-average amortization period     1 year 10 months 13 days    
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%   15.00%
Share price $ 118.04   $ 118.04    
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%   35.00%
Share price $ 151.04   $ 151.04