Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity - Schedule of All Options and Exercisable Options (Details)

v3.20.1
Stockholders' Equity - Schedule of All Options and Exercisable Options (Details)
 3 Months Ended 9 Months Ended
Jan. 31, 2020
$ / shares
shares
Jan. 31, 2020
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Outstanding (in shares) | shares 2,776,778 2,776,778
Exercisable (in shares) | shares 1,824,684 1,824,684
$1.57 to $2.10    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Minimum exercise price (in dollars per share) $ 1.57  
Maximum exercise price (in dollars per share) 2.10  
Weighted average exercise price (in dollars per share) $ 2.00 $ 2.00
Outstanding (in shares) | shares 564,724 564,724
Weighted average exercise price (in dollars per share) $ 2.00 $ 2.00
Weighted average remaining life in years   11 months 15 days
Exercisable (in shares) | shares 564,723 564,723
$2.28 to $2.76    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Minimum exercise price (in dollars per share) $ 2.28  
Maximum exercise price (in dollars per share) 2.76  
Weighted average exercise price (in dollars per share) $ 2.30 $ 2.30
Outstanding (in shares) | shares 382,780 382,780
Weighted average exercise price (in dollars per share) $ 2.29 $ 2.29
Weighted average remaining life in years   7 months 6 days
Exercisable (in shares) | shares 391,736 391,736
$3.24 to $4.38    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Minimum exercise price (in dollars per share) $ 3.24  
Maximum exercise price (in dollars per share) 4.38  
Weighted average exercise price (in dollars per share) $ 3.89 $ 3.89
Outstanding (in shares) | shares 323,925 323,925
Weighted average exercise price (in dollars per share) $ 3.91 $ 3.91
Weighted average remaining life in years   1 year 8 months 23 days
Exercisable (in shares) | shares 215,817 215,817
$4.50 to $5.20    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Minimum exercise price (in dollars per share) $ 4.5  
Maximum exercise price (in dollars per share) 5.20  
Weighted average exercise price (in dollars per share) $ 4.93 $ 4.93
Outstanding (in shares) | shares 708,960 708,960
Weighted average exercise price (in dollars per share) $ 4.90 $ 4.90
Weighted average remaining life in years   2 years 3 months 10 days
Exercisable (in shares) | shares 336,278 336,278
$5.95 to $6.28    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Minimum exercise price (in dollars per share) $ 5.95  
Maximum exercise price (in dollars per share) 6.28  
Weighted average exercise price (in dollars per share) $ 6.07 $ 6.07
Outstanding (in shares) | shares 80,417 80,417
Weighted average exercise price (in dollars per share) $ 6.13 $ 6.13
Weighted average remaining life in years   2 years 5 months 4 days
Exercisable (in shares) | shares 36,806 36,806
$7.17 to $7.55    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Minimum exercise price (in dollars per share) $ 7.17  
Maximum exercise price (in dollars per share) 7.55  
Weighted average exercise price (in dollars per share) $ 7.41 $ 7.41
Outstanding (in shares) | shares 551,639 551,639
Weighted average exercise price (in dollars per share) $ 7.32 $ 7.32
Weighted average remaining life in years   3 years 9 months 25 days
Exercisable (in shares) | shares 224,546 224,546
$8.57 to $9.07    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Minimum exercise price (in dollars per share) $ 8.57  
Maximum exercise price (in dollars per share) 9.07  
Weighted average exercise price (in dollars per share) $ 8.97 $ 8.97
Outstanding (in shares) | shares 164,333 164,333
Weighted average exercise price (in dollars per share) $ 8.97 $ 8.97
Weighted average remaining life in years   2 years 11 months 8 days
Exercisable (in shares) | shares 54,778 54,778