Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.2
Stockholders' Equity (Schedule of All Options and Exercisable Options) (Details)
3 Months Ended
Jul. 31, 2019
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL OPTIONS, Outstanding No. of Options | shares 3,237,840
EXERCISABLE OPTIONS, Exercisable No. of Options | shares 2,057,324
$1.57 to $2.10 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL OPTIONS, Exercise Price Lower Range $ 1.57
ALL OPTIONS, Exercise Price Upper Range 2.10
ALL OPTIONS, Weighted Average Exercise Price $ 1.98
ALL OPTIONS, Outstanding No. of Options | shares 736,577
EXERCISABLE OPTIONS, Weighted Average Exercise Price $ 1.98
EXERCISABLE OPTIONS, Weighted Average Remaining Life In Years 2 years 3 months 15 days
EXERCISABLE OPTIONS, Exercisable No. of Options | shares 736,577
$2.28 to $2.76 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL OPTIONS, Exercise Price Lower Range $ 2.28
ALL OPTIONS, Exercise Price Upper Range 2.76
ALL OPTIONS, Weighted Average Exercise Price $ 2.31
ALL OPTIONS, Outstanding No. of Options | shares 462,747
EXERCISABLE OPTIONS, Weighted Average Exercise Price $ 2.31
EXERCISABLE OPTIONS, Weighted Average Remaining Life In Years 1 year 1 month 2 days
EXERCISABLE OPTIONS, Exercisable No. of Options | shares 456,287
$3.24 to $4.38 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL OPTIONS, Exercise Price Lower Range $ 3.24
ALL OPTIONS, Exercise Price Upper Range 4.38
ALL OPTIONS, Weighted Average Exercise Price $ 3.86
ALL OPTIONS, Outstanding No. of Options | shares 363,223
EXERCISABLE OPTIONS, Weighted Average Exercise Price $ 3.90
EXERCISABLE OPTIONS, Weighted Average Remaining Life In Years 2 years 3 months 19 days
EXERCISABLE OPTIONS, Exercisable No. of Options | shares 274,127
$4.50 to $5.20 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL OPTIONS, Exercise Price Lower Range $ 4.50
ALL OPTIONS, Exercise Price Upper Range 5.20
ALL OPTIONS, Weighted Average Exercise Price $ 4.93
ALL OPTIONS, Outstanding No. of Options | shares 714,792
EXERCISABLE OPTIONS, Weighted Average Exercise Price $ 4.90
EXERCISABLE OPTIONS, Weighted Average Remaining Life In Years 2 years 9 months 14 days
EXERCISABLE OPTIONS, Exercisable No. of Options | shares 336,833
$5.95 to $6.28 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL OPTIONS, Exercise Price Lower Range $ 5.95
ALL OPTIONS, Exercise Price Upper Range 6.28
ALL OPTIONS, Weighted Average Exercise Price $ 6.07
ALL OPTIONS, Outstanding No. of Options | shares 80,417
EXERCISABLE OPTIONS, Weighted Average Exercise Price $ 6.13
EXERCISABLE OPTIONS, Weighted Average Remaining Life In Years 2 years 11 months 4 days
EXERCISABLE OPTIONS, Exercisable No. of Options | shares 36,806
$7.17 to $7.55 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL OPTIONS, Exercise Price Lower Range $ 7.17
ALL OPTIONS, Exercise Price Upper Range 7.55
ALL OPTIONS, Weighted Average Exercise Price $ 7.39
ALL OPTIONS, Outstanding No. of Options | shares 662,417
EXERCISABLE OPTIONS, Weighted Average Exercise Price $ 7.51
EXERCISABLE OPTIONS, Weighted Average Remaining Life In Years 3 years 10 months 28 days
EXERCISABLE OPTIONS, Exercisable No. of Options | shares 144,139
$8.57 to $9.07 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL OPTIONS, Exercise Price Lower Range $ 8.57
ALL OPTIONS, Exercise Price Upper Range 9.07
ALL OPTIONS, Weighted Average Exercise Price $ 8.98
ALL OPTIONS, Outstanding No. of Options | shares 217,667
EXERCISABLE OPTIONS, Weighted Average Exercise Price $ 8.98
EXERCISABLE OPTIONS, Weighted Average Remaining Life In Years 3 years 5 months 9 days
EXERCISABLE OPTIONS, Exercisable No. of Options | shares 72,555