Annual report pursuant to Section 13 and 15(d)

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

v3.20.4
Stock Plans - Summary of Fair Value Assumptions of Stock Purchase Plan (Detail) - $ / shares
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Performance-based Stock Options [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Grant date stock price $ 11.10  
Risk-free interest rate 0.80% 2.70%
Expected volatility 85.00% 65.00%
Minimum [Member] | Performance-based Stock Options [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Grant date stock price   $ 4.65
Maximum [Member] | Performance-based Stock Options [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Grant date stock price   $ 8.34
Employee Stock Purchase Plan [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility, minimum 65.00% 62.00%
Expected volatility, maximum 130.00% 71.00%
Risk-free interest rate, minimum 0.10% 1.70%
Risk-free interest rate, maximum 1.50% 2.50%
Employee Stock Purchase Plan [Member] | Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 6 months 6 months
Employee Stock Purchase Plan [Member] | Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 2 years 2 years