v3.20.4
Equity Incentive Plans - Schedule of Fair Value of Stock Option Award and ESPP on Grant Date (Detail) - Stock options [Member] - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Risk-free interest rate 0.26% 2.40% 2.50%
Expected term (in years) 3 years 10 months 24 days 4 years 6 months 4 years 8 months 12 days
Expected volatility 69.00% 48.00% 42.00%
Dividend yield 0.00% 0.00% 0.00%
Grant date fair value per share $ 216.14 $ 22.32 $ 24.38