v3.19.3.a.u2
Stock-Based Compensation - Stock Options (Details) - Stock options - USD ($)
$ / shares in Units, $ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Fair value assumptions and methodology      
Risk-free interest rate minimum (as a percent) 1.60% 2.30% 2.00%
Risk-free interest rate maximum (as a percent) 2.60% 3.00% 2.10%
Expected volatility minimum (as a percent) 45.00% 46.00% 46.00%
Expected volatility maximum (as a percent) 64.00% 49.00% 49.00%
Dividend yield (as a percent) 0.00% 0.00% 0.00%
Number of Options      
Outstanding balance at the beginning of the period (in shares) 4,057,788    
Granted (in shares) 809,289    
Exercised (in shares) (361,134)    
Forfeited (in shares) (116,435)    
Expired (in shares) (15,613)    
Outstanding balance at the end of the period (in shares) 4,373,895 4,057,788  
Exercisable at the end of the period (in shares) 3,051,658    
Weighted Average Exercise Price per Share      
Outstanding balance at the beginning of the period (in dollars per share) $ 27.23    
Granted (in dollars per share) 61.34    
Exercised (in dollars per share) 8.64    
Forfeited (in dollars per share) 56.00    
Expired (in dollars per share) 44.99    
Outstanding balance at the end of the period (in dollars per share) 34.24 $ 27.23  
Exercisable at the end of the period (in dollars per share) $ 20.98    
Weighted Average Remaining Contractual Term      
Outstanding balance 5 years 10 months 17 days 5 years 11 months 12 days  
Granted 8 years 4 months 6 days    
Exercised 1 year 4 months 9 days    
Exercisable at the end of the period 4 years 8 months 8 days    
Aggregate Intrinsic Value      
Outstanding balance at the end of the period $ 28,736 $ 113,211  
Exercisable at the end of the period $ 28,374    
Minimum      
Fair value assumptions and methodology      
Expected term in (years) 5 years 11 months 16 days 5 years 11 months 19 days 6 years
Maximum      
Fair value assumptions and methodology      
Expected term in (years) 6 years 29 days 6 years 9 months 7 days 6 years 29 days