v3.8.0.1
Stock-Based Compensation - Other (Details)
$ / shares in Units, $ in Millions
3 Months Ended
Mar. 31, 2018
USD ($)
$ / shares
shares
Stock options  
Number of Options  
Outstanding balance at the beginning of the period (in shares) | shares 4,559,176
Granted (in shares) | shares 8,731
Exercised (in shares) | shares (186,049)
Forfeited (in shares) | shares (47,246)
Outstanding balance at the end of the period (in shares) | shares 4,334,612
Exercisable at the end of the period (in shares) | shares 3,265,262
Weighted Average Exercise Price per Share  
Outstanding balance at the beginning of the period (in dollars per share) | $ / shares $ 15.10
Granted (in dollars per share) | $ / shares 64.51
Exercised (in dollars per share) | $ / shares 11.40
Forfeited (in dollars per share) | $ / shares 36.50
Outstanding balance at the end of the period (in dollars per share) | $ / shares 15.12
Exercisable at the end of the period (in dollars per share) | $ / shares $ 9.21
Weighted Average Remaining Contractual Term (in years)  
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term 4 years 8 months 16 days
Aggregate Intrinsic Value  
Exercisable at the end of the period | $ $ 244.3
Restricted Stock Units  
Summary of restricted stock unit activity  
Outstanding balance at the beginning of the period (in shares) | shares 1,413,423
Granted (in shares) | shares 64,184
Vested (in shares) | shares (167,595)
Forfeited (in shares) | shares (28,132)
Outstanding balance at the end of the period (in shares) | shares 1,281,880
Weighted-Average Grant-Date Fair value  
Outstanding at the beginning of the period (in dollars per share) | $ / shares $ 29.95
Granted (in dollars per share) | $ / shares 64.51
Vested (in dollars per share) | $ / shares 11.45
Forfeited (in dollars per share) | $ / shares 35.67
Outstanding at the end of the period (in dollars per share) | $ / shares $ 33.97