Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail)

v3.20.2
Stock-Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail) - USD ($)
$ / shares in Units, $ in Millions
9 Months Ended 12 Months Ended
Sep. 30, 2020
Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Number of Shares, Outstanding, Beginning Balance 4,763,062  
Number of Shares, Granted 2,374,006  
Number of Shares, Exercised (240,659)  
Number of Shares, Forfeitures (104,436)  
Number of Shares, Outstanding, Ending Balance 6,791,973 4,763,062
Number of Shares, Exercisable 2,554,485  
Weighted-Average Exercise Price, Outstanding, Beginning Balance $ 6.36  
Weighted-Average Exercise Price, Granted 14.23  
Weighted-Average Exercise Price, Exercised 3.87  
Weighted-Average Exercise Price, Forfeitures 11.12  
Weighted-Average Exercise Price, Outstanding, Ending Balance 9.12 $ 6.36
Weighted-Average Exercise Price, Exercisable $ 6.47  
Weighted-Average Remaining Contractual Term, Outstanding 8 years 2 months 12 days 8 years 1 month 6 days
Weighted-Average Remaining Contractual Term, Exercisable 7 years 1 month 6 days  
Aggregate Intrinsic Value, Outstanding $ 20.5 $ 36.6
Aggregate Intrinsic Value, Exercisable $ 11.9