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Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.2
Stockholders' Equity - Schedule of All Options and Exercisable Options (Details) - $ / shares
3 Months Ended
Jul. 31, 2020
Apr. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Outstanding (in shares) 2,314,036 2,734,899
Exercisable (in shares) 1,884,793 Ìý
$1.57 to $2.10 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 1.57 Ìý
Maximum exercise price (in dollars per share) 2.10 Ìý
Weighted average exercise price (in dollars per share) $ 2.02 Ìý
Outstanding (in shares) 306,166 Ìý
Weighted average exercise price (in dollars per share) $ 2.02 Ìý
Weighted average remaining life in years 6 months 21 days Ìý
Exercisable (in shares) 261,771 Ìý
$2.28 to $2.76 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 2.28 Ìý
Maximum exercise price (in dollars per share) 2.76 Ìý
Weighted average exercise price (in dollars per share) $ 2.30 Ìý
Outstanding (in shares) 307,779 Ìý
Weighted average exercise price (in dollars per share) $ 2.30 Ìý
Weighted average remaining life in years 3 months 7 days Ìý
Exercisable (in shares) 307,779 Ìý
$3.24 to $4.38 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 3.24 Ìý
Maximum exercise price (in dollars per share) 4.38 Ìý
Weighted average exercise price (in dollars per share) $ 3.90 Ìý
Outstanding (in shares) 318,174 Ìý
Weighted average exercise price (in dollars per share) $ 3.87 Ìý
Weighted average remaining life in years 1 year 3 months 25 days Ìý
Exercisable (in shares) 262,507 Ìý
$4.50 to $5.20 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 4.5 Ìý
Maximum exercise price (in dollars per share) 5.20 Ìý
Weighted average exercise price (in dollars per share) $ 4.93 Ìý
Outstanding (in shares) 665,195 Ìý
Weighted average exercise price (in dollars per share) $ 4.91 Ìý
Weighted average remaining life in years 1 year 11 months 23 days Ìý
Exercisable (in shares) 536,597 Ìý
$5.95 to $6.28 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 5.95 Ìý
Maximum exercise price (in dollars per share) 6.28 Ìý
Weighted average exercise price (in dollars per share) $ 6.08 Ìý
Outstanding (in shares) 75,751 Ìý
Weighted average exercise price (in dollars per share) $ 6.11 Ìý
Weighted average remaining life in years 1 year 11 months 15 days Ìý
Exercisable (in shares) 61,195 Ìý
$7.17 to $7.55 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 7.17 Ìý
Maximum exercise price (in dollars per share) 7.55 Ìý
Weighted average exercise price (in dollars per share) $ 7.44 Ìý
Outstanding (in shares) 481,639 Ìý
Weighted average exercise price (in dollars per share) $ 7.41 Ìý
Weighted average remaining life in years 3 years 1 month 28 days Ìý
Exercisable (in shares) 342,056 Ìý
$8.57 to $9.07 Ìý Ìý
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Ìý Ìý
Minimum exercise price (in dollars per share) $ 8.57 Ìý
Maximum exercise price (in dollars per share) 9.07 Ìý
Weighted average exercise price (in dollars per share) $ 8.98 Ìý
Outstanding (in shares) 159,332 Ìý
Weighted average exercise price (in dollars per share) $ 8.98 Ìý
Weighted average remaining life in years 2 years 5 months 8 days Ìý
Exercisable (in shares) 112,888 Ìý