Annual report pursuant to Section 13 and 15(d)

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

v3.19.2
Stockholders' Equity (Schedule of All Warrants and Exercisable Warrants) (Details)
12 Months Ended
Apr. 30, 2019
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL WARRANTS, Outstanding No. of Warrants | shares 3,409,154
EXERCISABLE WARRANTS, Exercisable No. of Warrants | shares 2,244,861
Warrant [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL WARRANTS, Outstanding No. of Warrants | shares 731,152
EXERCISABLE WARRANTS, Exercisable No. of Warrants | shares 681,152
Warrant [Member] | $2.28 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL WARRANTS, Exercise Price Upper Range $ 2.28
ALL WARRANTS, Weighted Average Exercise Price $ 2.28
ALL WARRANTS, Outstanding No. of Warrants | shares 164,929
EXERCISABLE WARRANTS, Weighted Average Exercise Price $ 2.28
EXERCISABLE WARRANTS, Weighted Average Remaining Life In Years 3 months 15 days
EXERCISABLE WARRANTS, Exercisable No. of Warrants | shares 164,929
Warrant [Member] | $4.89 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL WARRANTS, Exercise Price Upper Range $ 4.89
ALL WARRANTS, Weighted Average Exercise Price $ 4.89
ALL WARRANTS, Outstanding No. of Warrants | shares 50,000
EXERCISABLE WARRANTS, Weighted Average Exercise Price $ 4.89
EXERCISABLE WARRANTS, Weighted Average Remaining Life In Years 4 years 11 months 12 days
EXERCISABLE WARRANTS, Exercisable No. of Warrants | shares
Warrant [Member] | $5.85 to $6.00 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL WARRANTS, Exercise Price Lower Range $ 5.85
ALL WARRANTS, Exercise Price Upper Range 6.00
ALL WARRANTS, Weighted Average Exercise Price $ 5.95
ALL WARRANTS, Outstanding No. of Warrants | shares 292,049
EXERCISABLE WARRANTS, Weighted Average Remaining Life In Years 4 years 9 months
EXERCISABLE WARRANTS, Exercisable No. of Warrants | shares 292,049
Warrant [Member] | $5.85 to $6.00 [Member] | Minimum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
EXERCISABLE WARRANTS, Weighted Average Exercise Price $ 5.85
Warrant [Member] | $5.85 to $6.00 [Member] | Maximum [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
EXERCISABLE WARRANTS, Weighted Average Exercise Price 6.00
Warrant [Member] | $6.87 [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
ALL WARRANTS, Exercise Price Upper Range 6.87
ALL WARRANTS, Weighted Average Exercise Price $ 6.87
ALL WARRANTS, Outstanding No. of Warrants | shares 224,174
EXERCISABLE WARRANTS, Weighted Average Exercise Price $ 6.87
EXERCISABLE WARRANTS, Weighted Average Remaining Life In Years 3 years 2 months 27 days
EXERCISABLE WARRANTS, Exercisable No. of Warrants | shares 224,174