Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Share-based Payment Arrangement, Option, Exercise Price Range (Details)

v3.21.2
Stockholders' Equity - Share-based Payment Arrangement, Option, Exercise Price Range (Details)
 3 Months Ended
Jul. 31, 2021
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Outstanding (in shares) | shares 1,207,624
Exercisable (in shares) | shares 1,141,396
Warrant  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Outstanding (in shares) | shares 399,174
Exercisable (in shares) | shares 374,174
Warrant | $4.89  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Minimum exercise price (in dollars per share) $ 4.89
Maximum exercise price (in dollars per share) 4.89
Weighted average exercise price (in dollars per share) $ 4.89
Outstanding (in shares) | shares 50,000
Weighted average exercise price (in dollars per share) $ 4.89
Weighted average remaining life in years 3 years 5 months 8 days
Exercisable (in shares) | shares 50,000
Warrant | $6.00  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Minimum exercise price (in dollars per share) $ 6.00
Maximum exercise price (in dollars per share) 6.00
Weighted average exercise price (in dollars per share) $ 6.00
Outstanding (in shares) | shares 100,000
Weighted average exercise price (in dollars per share) $ 6.00
Weighted average remaining life in years 3 years 1 month 2 days
Exercisable (in shares) | shares 100,000
Warrant | $6.87  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Minimum exercise price (in dollars per share) $ 6.87
Maximum exercise price (in dollars per share) 6.87
Weighted average exercise price (in dollars per share) $ 6.87
Outstanding (in shares) | shares 224,174
Weighted average exercise price (in dollars per share) $ 6.87
Weighted average remaining life in years 1 year 5 months 23 days
Exercisable (in shares) | shares 224,174
Warrant | $6.99  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Minimum exercise price (in dollars per share) $ 6.99
Maximum exercise price (in dollars per share) 6.99
Weighted average exercise price (in dollars per share) $ 6.99
Outstanding (in shares) | shares 25,000
Weighted average exercise price (in dollars per share) $ 0
Weighted average remaining life in years 0 years
Exercisable (in shares) | shares 0