Quarterly report pursuant to Section 13 or 15(d)

Stock Based Compensation - Summary of Fair Values of Stock Options Granted (Detail)

v3.21.2
Stock Based Compensation - Summary of Fair Values of Stock Options Granted (Detail) - Employee Stock Purchase Plan [Member] - Employee Stock Option [Member]
9 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Dividend yield 0.00% 0.00%
Expected life 6 months 6 months
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 95.00% 61.00%
Risk-free interest rate 0.05% 0.17%
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected volatility 143.00% 182.00%
Risk-free interest rate 0.09% 1.57%