Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Stockholders' Equity (Schedule of Stock Options Activity) (Details)
 9 Months Ended
Jan. 31, 2019
USD ($)
$ / shares
shares
Number of Shares  
Exercised (49,792)
Stock Incentive Plan and Stock Option Grants to Employees and Directors [Member]  
Number of Shares  
Balance Outstanding, April 30, 2018 2,980,010
Granted 918,667
Exercised (195,629)
Forfeited (51,600)
Expired
Balance Outstanding, January 31, 2019 3,651,448
Exercisable, January 31, 2019 1,630,252
Weighted Average Exercise Price  
Balance Outstanding, April 30, 2018 | $ / shares $ 3.62
Granted | $ / shares 7.12
Exercised | $ / shares 2.23
Forfeited | $ / shares
Expired | $ / shares
Balance Outstanding, January 31, 2019 | $ / shares 4.52
Exercisable, January 31, 2019 | $ / shares $ 2.65
Balance Outstanding, January 31, 2019 3 years 29 days
Exercisable, January 31, 2019 2 years 15 days
Aggregate Intrinsic Value  
Balance Outstanding, April 30, 2018 | $ $ 16,558,373
Balance Outstanding, January 31, 2019 | $ 10,081,298
Exercisable, January 31, 2019 | $ $ 7,862,357