v3.20.2
Stock-Based Compensation - Summary of Stock Option Activity (Detail)
$ / shares in Units, $ in Thousands
 9 Months Ended 12 Months Ended
Sep. 30, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
$ / shares
shares
Share-based Payment Arrangement [Abstract]    
Beginning Balance of Options Outstanding | shares 497,441,159  
Options granted | shares 397,885,337  
Options exercised | shares (69,444,099)  
Options canceled and forfeitedOptions canceled and forfeited | shares (238,005,542)  
Ending Balance of Options Outstanding | shares 587,876,855 497,441,159
Options vested and exercisable as of September 30, 2020 | shares 344,033,233  
Beginning Balance of Weighted-Average Exercise Price Per Share | $ / shares $ 4.10  
Options granted | $ / shares 7.43  
Options exercised | $ / shares 1.67  
Options canceled and forfeited | $ / shares 5.95  
Ending Balance of Weighted-Average Exercise Price Per Share | $ / shares 5.89 $ 4.10
Options vested and exercisable as of September 30, 2020 | $ / shares $ 3.64  
Weighted- Average Remaining Contractual Life (years) 7 years 11 months 26 days 5 years 9 months 21 days
Options vested and exercisable as of September 30, 2020 5 years 10 months 24 days  
Beginning Balance of Aggregate Intrinsic Value | $   $ 975,798
Ending Balance of Aggregate Intrinsic Value | $ $ 2,120,561  
Options vested and exercisable as of September 30, 2020 | $ $ 2,014,537