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Stock-Based Compensation - Summary of Share Based Compensation Valuation of Options Granted Assumptions (Detail) - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Employee Stock Purchase Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected volatility, minimum 47.00% 44.00%  
Expected volatility, maximum 53.00% 55.00%  
Expected volatility     37.00%
Risk-free interest rate, minimum 0.10% 1.90% 2.00%
Risk-free interest rate, maximum 0.30% 2.50% 2.60%
Expected dividend yield 0.00% 0.00% 0.00%
Options to Purchase Common Stock      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Grant date fair value per share, maximum (in dollars per share)     $ 11.86
Minimum | Employee Stock Purchase Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term 6 months 6 months 6 months
Grant date fair value per share, maximum (in dollars per share) $ 9.63 $ 14.17 $ 6.62
Maximum | Employee Stock Purchase Plan      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term 1 year 1 year 1 year
Grant date fair value per share, maximum (in dollars per share) $ 22.30 $ 17.94 $ 10.95