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Stock Options and Stock-Based Compensation - Additional Information (Detail) - USD ($)
1 Months Ended 3 Months Ended
Jun. 30, 2021
Jul. 31, 2021
Jul. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Directors' fees paid with shares of common stock in lieu of cash in accordance with Director compensation guidelines   $ 41,000 $ 41,000
2017 Plan | Restricted Stock Units (RSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Stock-based compensation expense   194,000 $ 59,000
Remaining estimated compensation expense   $ 1,325,000  
2017 Plan | Restricted Stock Units (RSUs) | Tranche One      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock units granted (in shares) 5,500    
Vesting period (in years) 2 years    
2017 Plan | Restricted Stock Units (RSUs) | Tranche Two      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock units granted (in shares) 51,471    
Vesting period (in years) 3 years