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Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
Stockholders' Equity (Schedule of Stock Options Activity) (Details) - Stock Incentive Plan and Stock Option Grants to Employees and Directors [Member]
 3 Months Ended
Jul. 31, 2017
USD ($)
$ / shares
shares
Number of Shares  
Balance outstanding | shares 2,097,384
Granted | shares 535,500
Exercised | shares
Forfeited | shares
Expired | shares
Balance outstanding | shares 2,632,884
Exercisable | shares 1,377,363
Weighted Average Exercise Price  
Balance outstanding | $ / shares $ 2.42
Granted | $ / shares 4.98
Exercised | $ / shares
Forfeited | $ / shares
Expired | $ / shares
Balance outstanding | $ / shares 2.94
Exercisable | $ / shares $ 2.28
Beginning balance outstanding 3 years 1 month 2 days
Ending balance outstanding 3 years 1 month 20 days
Exercisable 1 year 6 months 10 days
Aggregate Intrinsic Value  
Balance outstanding | $ $ 7,267,892
Balance outstanding | $ 16,732,558
Exercisable | $ $ 8,689,038