Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.2
Stock Based Compensation - Summary of Fair Values of Stock Options Granted (Detail) - Employee Stock Purchase Plan [Member] - Employee Stock Option [Member] - $ / shares
6 Months Ended
Jun. 30, 2020
Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Stock price $ 1.77 $ 5.79
Dividend yield 0.00% 0.00%
Expected volatility 61.00% 96.00%
Risk-free interest rate 1.57% 2.51%
Expected life 6 months 6 months