Quarterly report pursuant to Section 13 or 15(d)

Stock Plans - Summary of Fair Value Assumptions of Stock Purchase Plan (Detail)

v3.20.2
Stock Plans - Summary of Fair Value Assumptions of Stock Purchase Plan (Detail) - Employee Stock Purchase Plan [Member]
9 Months Ended
Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected volatility, minimum 65.00%
Expected volatility, maximum 130.00%
Risk-free interest rate, minimum 0.10%
Risk-free interest rate, maximum 1.50%
Minimum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected term (in years) 6 years
Maximum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected term (in years) 2 years