Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation (Summary of Stock Option Activity) (Details)

v3.20.4
Stock-Based Compensation (Summary of Stock Option Activity) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Payment Arrangement [Abstract]        
Options outstanding, beginning, number of shares 1,479,674 1,604,621 1,769,887  
Granted, number of shares 660,071 395,653 402,010  
Cancelled, number of shares (78,163) (68,275) (67,440)  
Exercised, number of shares (142,419) (452,325) (499,836)  
Options outstanding, ending, number of shares 1,919,163 1,479,674 1,604,621 1,769,887
Options outstanding, beginning, weighted average exercise price $ 66.74 $ 53.86 $ 44.22  
Granted, weighted average exercise price 87.25 93.98 76.48  
Cancelled, weighted average exercise price 83.76 74.10 60.75  
Exercised, weighted average exercise price 48.58 43.76 36.98  
Options outstanding, ending, weighted average exercise price $ 74.45 $ 66.74 $ 53.86 $ 44.22
Options outstanding, beginning, weighted average remaining contractual life, years 7 years 2 months 8 days 7 years 1 month 9 days 6 years 11 months 12 days 6 years 8 months 8 days
Options outstanding, ending, weighted average remaining contractual life, years 7 years 2 months 8 days 7 years 1 month 9 days 6 years 11 months 12 days 6 years 8 months 8 days
Options outstanding, beginning, aggregate intrinsic value $ 49,930 $ 48,703 $ 48,962  
Options outstanding, ending, aggregate intrinsic value $ 29,489 $ 49,930 $ 48,703 $ 48,962
Options vested and expected to vest, number of shares 1,839,590      
Options vested and expected to vest, weighted average exercise price $ 73.88      
Options vested and expected to vest, weighted average remining contractual life, years 7 years 1 month 13 days      
Options vested and expected to vest, aggregate intrinsic value $ 29,185      
Options exercisable, number of shares 806,320      
Options exercisable, weighted average exercise price $ 60.31      
Options exercisable, weighted average remaining contractual life 5 years 6 months 10 days      
Options exercisable, aggregate intrinsic value $ 22,620