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Stock Plans and Stock-Based Compensation - Schedule of Assumptions Used in Determining Fair Value of Stock Option Grants (Details) - $ / shares
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Dividend rate     0.00%  
2016 Employee Stock Purchase Plan        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Expected term (in years) 6 months 6 months 6 months 6 months
Expected volatility   60.00%   60.00%
Expected volatility, maximum 50.00%   60.00%  
Expected volatility, minimum 45.00%   45.00%  
Risk-free interest rate   1.18%    
Risk-free interest rate, maximum 2.33%   2.33% 1.18%
Risk-free interest rate, minimum 1.89%   1.18% 0.45%
Dividend rate 0.00% 0.00% 0.00% 0.00%
Employee Stock Options        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Market price per share on grant date $ 58.75      
Expected term (in years) 6 years 6 years 6 years  
Expected volatility 45.00% 60.00%   60.00%
Expected volatility, maximum     50.00%  
Expected volatility, minimum     45.00%  
Risk-free interest rate 2.72%      
Risk-free interest rate, maximum   1.93% 2.98% 2.47%
Risk-free interest rate, minimum   1.82% 2.72% 1.82%
Dividend rate 0.00% 0.00% 0.00% 0.00%
Employee Stock Options | Maximum        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Market price per share on grant date   $ 23.60 $ 58.75 $ 24.87
Expected term (in years)       6 years 1 month 9 days
Employee Stock Options | Minimum        
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]        
Market price per share on grant date   $ 23.17 $ 33.06 $ 18.05
Expected term (in years)       6 years