XML 42 R26.htm IDEA: XBRL DOCUMENT v3.21.1
Stock-Based Compensation - Summary of Fair Values of Stock Options Granted and Assumptions used in Black-Scholes Model (Detail) - Stock Options [Member] - $ / shares
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Estimated fair values of stock options granted $ 5.85 $ 5.19
Risk-free interest rate 0.60% 1.70%
Expected volatility 85.00% 77.40%
Expected term (in years)   6 years 10 months 24 days
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 5 years 8 months 12 days  
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 6 years 2 months 12 days