Quarterly report pursuant to Section 13 or 15(d)

Assumptions Used in Estimating Fair Value of Stock Options Granted (Detail)

v3.20.2
Assumptions Used in Estimating Fair Value of Stock Options Granted (Detail)
3 Months Ended 6 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Jun. 30, 2020
Jun. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions And Methodology [Abstract]        
Expected term (years) 5 years 6 months 6 years 1 month 6 days 5 years 6 months 6 years 1 month 6 days
Volatility 103.10% 85.00% 102.80% 85.80%
Risk-free interest rate 0.36% 2.50% 0.37% 2.60%