Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Schedule of Stock Options Activity) (Details)

v3.19.2
Stockholders' Equity (Schedule of Stock Options Activity) (Details)
 12 Months Ended
Apr. 30, 2019
USD ($)
$ / shares
shares
Number of Shares  
Balance Outstanding, April 30, 2018  
Balance Outstanding, April 30, 2019 3,409,154
Exercisable, April 30, 2019 2,244,861
Stock Incentive Plan and Stock Option Grants to Employees and Directors [Member]  
Number of Shares  
Balance Outstanding, April 30, 2018 2,980,010
Granted 1,006,542
Exercised (251,186)
Forfeited (326,212)
Expired
Balance Outstanding, April 30, 2019 3,409,154
Exercisable, April 30, 2019 2,244,861
Weighted Average Exercise Price  
Balance Outstanding, April 30, 2018 | $ / shares $ 3.62
Granted | $ / shares 6.88
Exercised | $ / shares 2.30
Forfeited | $ / shares 6.47
Expired | $ / shares
Balance Outstanding, April 30, 2019 | $ / shares 4.44
Exercisable, April 30, 2019 | $ / shares $ 3.35
Weighted Average Remaining Contractual Term  
Balance Outstanding, April 30, 2018 3 years 1 month 24 days
Balance Outstanding, April 30, 2019 2 years 10 months 25 days
Exercisable, April 30, 2019 2 years 3 months 22 days
Aggregate Intrinsic Value  
Balance Outstanding, April 30, 2018 | $ $ 16,558,373
Granted | $
Forfeited | $
Balance Outstanding, April 30, 2019 | $ 6,880,644
Exercisable, April 30, 2019 | $ $ 6,868,206