v3.10.0.1
Stock-Based Compensation - Other (Details) - USD ($)
$ / shares in Units, $ in Millions
 9 Months Ended
Sep. 30, 2018
Stock options  
Number of Options  
Outstanding balance at the beginning of the period (in shares) 4,559,176
Granted (in shares) 663,615
Exercised (in shares) (1,000,574)
Forfeited (in shares) (124,737)
Expired (in shares) 0
Outstanding balance at the end of the period (in shares) 4,097,480
Exercisable at the end of the period (in shares) 2,814,863
Weighted-Average Exercise Price per Share  
Outstanding balance at the beginning of the period (in dollars per share) $ 15.10
Granted (in dollars per share) 84.13
Exercised (in dollars per share) 7.03
Forfeited (in dollars per share) 41.20
Expired (in dollars per share) 0.00
Outstanding balance at the end of the period (in dollars per share) 27.45
Exercisable at the end of the period (in dollars per share) $ 13.34
Intrinsic value of options exercisable at the end of the period $ 174.2
Weighted-average remaining contractual term of options exercisable at the end of the period 5 years 29 days
Restricted Stock Units  
Summary of restricted stock unit activity  
Outstanding balance at the beginning of the period (in shares) 1,413,423
Granted (in shares) 523,281
Vested (in shares) (585,799)
Forfeited (in shares) (133,744)
Outstanding balance at the end of the period (in shares) 1,217,161
Weighted-Average Grant-Date Fair value  
Outstanding at the beginning of the period (in dollars per share) $ 29.95
Granted (in dollars per share) 81.74
Vested (in dollars per share) 25.54
Forfeited (in dollars per share) 43.98
Outstanding at the end of the period (in dollars per share) $ 52.80