Quarterly report pursuant to Section 13 or 15(d)

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

v3.8.0.1
Stockholders' Equity (Schedule of Stock Options Activity) (Details) - Stock Incentive Plan and Stock Option Grants to Employees and Directors [Member]
 6 Months Ended
Oct. 31, 2017
USD ($)
$ / shares
shares
Number of Shares  
Balance Outstanding, April 30, 2017 | shares 2,097,384
Granted | shares 588,500
Exercised | shares (16,598)
Forfeited | shares
Expired | shares
Balance Outstanding, October 31, 2017 | shares 2,669,286
Exercisable, October 31, 2017 | shares 1,449,136
Weighted Average Exercise Price  
Balance Outstanding, April 30, 2017 | $ / shares $ 2.42
Granted | $ / shares 5.07
Exercised | $ / shares 4.20
Forfeited | $ / shares
Expired | $ / shares
Balance Outstanding, October 31, 2017 | $ / shares 2.99
Exercisable, October 31, 2017 | $ / shares $ 2.25
Balance Outstanding, April 30, 2017 3 years 1 month 6 days
Granted 5 years
Exercised 0 years
Balance Outstanding, October 31, 2017 3 years 2 months 12 days
Exercisable, October 31, 2017 1 year 3 months 19 days
Aggregate Intrinsic Value  
Balance Outstanding, April 30, 2017 | $ $ 7,267,892
Granted | $ 843,750
Forfeited | $
Balance Outstanding, October 31, 2017 | $ 17,291,782
Exercisable, October 31, 2017 | $ $ 11,249,199