Stockholders' Equity - Summary of Stock Options Activity (Details) - $ / shares	9 Months Ended	12 Months Ended
	Jan. 31, 2019	Apr. 30, 2018
Equity [Abstract]
Options, Outstanding at beginning of period	9,355,000	9,138,000
Options, Granted during the period		1,900,000
Options, Exercised during the period		(155,000)
Options, Forfeited or expired during the period		(1,528,000)
Options, Outstanding at end of period	9,355,000	9,355,000
Options, Exercisable at end of period	9,163,750	9,163,750
Weighted Average Exercise Price, Outstanding at beginning of period	$ 0.52	$ 0.31
Weighted Average Exercise Price, Granted during the period		1.17
Weighted Average Exercise Price, Exercised during the period		0.10
Weighted Average Exercise Price, Forfeited or expired during the period		0.20
Weighted Average Exercise Price, Outstanding at end of period	0.52	0.52
Weighted Average Exercise Price, Exercisable at end of period	$ 0.53	$ 0.53