Stockholders' Equity - Schedule of Stock Warrant Activity (Details)	3 Months Ended
	Jul. 31, 2020 $ / shares shares
Number of Warrants Outstanding, End of Period | shares	746,753
Warrants exercisable at end of period | shares	389,611
Weighted Average Exercise Price of Warrants Outstanding, End of Period	$ 13.82
Weighted Average Exercise Price, exercisable at end of period	20.07
Weighted average fair value of warrants granted during the period
Weighted Average Remaining Contractual Life in Years, End of Period	3 years 7 months 13 days
Warrants with No Class Designation [Member]
Number of Warrants Outstanding, Beginning of Period | shares	527,378
Number of Warrants, Granted | shares
Number of Warrants, Exercised | shares
Number of Warrants, Forfeited | shares
Number of Warrants, Canceled | shares
Number of Warrants Outstanding, End of Period | shares	527,378
Weighted Average Exercise Price of Warrants Outstanding, Beginning of Period	$ 14.83
Weighted Average Exercise Price, Granted
Weighted Average Exercise Price, Exercised
Weighted Average Exercise Price, Forfeited, with no financial effect
Weighted Average Exercise Price, Canceled
Weighted Average Exercise Price of Warrants Outstanding, End of Period	$ 14.83
Weighted Average Remaining Contractual Life in Years, Beginning of Period	3 years 8 months 23 days
Weighted Average Remaining Contractual Life in Years, Granted	0 years
Weighted Average Remaining Contractual Life in Years, End of Period	3 years 5 months 23 days
Class A Warrants [Member]
Number of Warrants Outstanding, Beginning of Period | shares	219,375
Number of Warrants, Granted | shares
Number of Warrants, Exercised | shares
Number of Warrants, Forfeited | shares
Number of Warrants, Canceled | shares
Number of Warrants Outstanding, End of Period | shares	219,375
Weighted Average Exercise Price of Warrants Outstanding, Beginning of Period	$ 11.40
Weighted Average Exercise Price, Granted
Weighted Average Exercise Price, Exercised
Weighted Average Exercise Price, Forfeited, with no financial effect
Weighted Average Exercise Price, Canceled
Weighted Average Exercise Price of Warrants Outstanding, End of Period	$ 11.40
Weighted Average Remaining Contractual Life in Years, Beginning of Period	4 years 2 months 19 days
Weighted Average Remaining Contractual Life in Years, Granted	0 years
Weighted Average Remaining Contractual Life in Years, End of Period	3 years 11 months 19 days