Annual report pursuant to Section 13 and 15(d)

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

v3.10.0.1
Stock-Based Compensation (Summary of Stock Option Activity) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]        
Options outstanding, beginning, number of shares 1,769,887 2,151,542 2,288,870  
Granted, number of shares 402,010 540,537 430,544  
Cancelled, number of shares (67,440) (246,450) (117,699)  
Exercised, number of shares (499,836) (675,742) (450,173)  
Options outstanding, ending, number of shares 1,604,621 1,769,887 2,151,542 2,288,870
Options outstanding, beginning, weighted average exercise price $ 44.22 $ 37.40 $ 32.69  
Granted, weighted average exercise price 76.48 55.90 56.63  
Cancelled, weighted average exercise price 60.75 50.62 47.33  
Exercised, weighted average exercise price 36.98 29.52 29.25  
Options outstanding, ending, weighted average exercise price $ 53.86 $ 44.22 $ 37.40 $ 32.69
Options outstanding, beginning, weighted average remaining contractual life, years 6 years 11 months 12 days 6 years 8 months 7 days 6 years 4 months 22 days 6 years 6 months
Options outstanding, ending, weighted average remaining contractual life, years 6 years 11 months 12 days 6 years 8 months 7 days 6 years 4 months 22 days 6 years 6 months
Options outstanding, beginning, aggregate intrinsic value $ 48,962 $ 45,253 $ 38,209  
Options outstanding, ending, aggregate intrinsic value $ 48,703 $ 48,962 $ 45,253 $ 38,209
Options vested and expected to vest, number of shares 1,542,039      
Options vested and expected to vest, weighted average exercise price $ 53.31      
Options vested and expected to vest, weighted average remining contractual life, years 6 years 10 months 17 days      
Options vested and expected to vest, aggregate intrinsic value $ 47,647      
Options exercisable, number of shares 703,049      
Options exercisable, weighted average exercise price $ 40.39      
Options exercisable, weighted average remaining contractual life 5 years 1 month 28 days      
Options exercisable, aggregate intrinsic value $ 30,727