Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity - Stock Option Plan Activity (Details)

v3.8.0.1
Stockholders' Equity - Stock Option Plan Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Shares [Rollforward]    
Balance at Beginning of Period (shares) 1,754,275  
Granted (shares) 273,353  
Exercised (shares) (148,252)  
Forfeited (shares) (3,044)  
Balance at End of Period (shares) 1,876,332 1,754,275
Exercisable at December 31, 2016 (shares) 1,431,245  
Options vested and expected to vest as of December 31, 2016 (shares) 1,876,332  
Weighted Average Exercise Price [Roll Forward]    
Balance at Beginning of Period (in usd per share) $ 42.12  
Granted (in usd per share) 112.58  
Exercised (in usd per share) 31.58  
Forfeited (in usd per share) 79.74  
Balance at End of Period (in usd per share) 53.17 $ 42.12
Exercisable at December 31, 2016 (in usd per share) 40.08  
Options vested and expected to vest as of December 31, 2016 (in usd per share) $ 53.17  
Weighted Average Remaining Contractual Term in Years 5 years 8 months 37 days 6 years 1 month 38 days
Exercisable, Weighted Average Remaining Contractual Term in Years 4 years 11 months 12 days  
Options vested and expected to vest, Weighted Average Remaining Contractual Term in Years 5 years 8 months 37 days  
Aggregate Intrinsic Value $ 157,340 $ 104,247
Exercisable, Aggregate Intrinsic Value 138,616  
Options vested and expected to vest, Aggregate Intrinsic Value $ 157,340