Segment Reporting - Additional Information (Detail) - USD ($)	9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
Washington Gold [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Average Segment Assets	$ 29,713,693	$ 27,352,824
South Dakota Gold [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Average Segment Assets		1,549,392
Corporate Segment [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information Average Segment Assets	$ 13,216,305	$ 3,793,289