Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.1
Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 12 Months Ended
Mar. 31, 2020
Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Number of Shares, Outstanding, Beginning Balance 4,743,990  
Number of Shares, Granted 1,713,706  
Number of Shares, Exercised (114,777)  
Number of Shares, Forfeitures (48,457)  
Number of Shares, Outstanding, Ending Balance 6,294,462 4,743,990
Number of Shares, Exercisable 2,028,825  
Weighted-Average Exercise Price, Outstanding, Beginning Balance $ 6.37  
Weighted-Average Exercise Price, Granted 14.51  
Weighted-Average Exercise Price, Exercised 2.62  
Weighted-Average Exercise Price, Forfeitures 11.07  
Weighted-Average Exercise Price, Outstanding, Ending Balance 8.62 $ 6.37
Weighted-Average Exercise Price, Exercisable $ 6.17  
Weighted-Average Remaining Contractual Term, Outstanding 8 years 6 months 8 years 2 months 12 days
Weighted-Average Remaining Contractual Term, Exercisable 7 years 2 months 12 days  
Aggregate Intrinsic Value, Outstanding $ 31.8 $ 36.5
Aggregate Intrinsic Value, Exercisable $ 14.8