Quarterly report pursuant to Section 13 or 15(d)

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

v3.10.0.1
Stockholders' Equity (Schedule of Stock Options Activity) (Details)
6 Months Ended
Oct. 31, 2018
USD ($)
$ / shares
shares
Number of Shares  
Exercised (26,807)
Stock Incentive Plan and Stock Option Grants to Employees and Directors [Member]  
Number of Shares  
Balance Outstanding, April 30, 2018 2,979,510
Granted 560,000
Exercised (72,643)
Forfeited (31,251)
Expired
Balance Outstanding, October 31, 2018 3,435,616
Exercisable, October 31, 2018 1,752,034
Weighted Average Exercise Price  
Balance Outstanding, April 30, 2018 | $ / shares $ 3.62
Granted | $ / shares 7.55
Exercised | $ / shares 2.43
Forfeited | $ / shares
Expired | $ / shares
Balance Outstanding, October 31, 2018 | $ / shares 4.25
Exercisable, October 31, 2018 | $ / shares $ 2.62
Balance Outstanding, October 31, 2018 3 years 22 days
Exercisable, October 31, 2018 2 years 2 months 23 days
Aggregate Intrinsic Value  
Balance Outstanding, April 30, 2018 | $ $ 16,558,373
Balance Outstanding, October 31, 2018 | $ 10,765,680
Exercisable, October 31, 2018 | $ $ 8,533,721