REVENUES - Additional Information (Details)	3 Months Ended		6 Months Ended
	Oct. 31, 2021 USD ($) ft² customer	Oct. 31, 2020 USD ($) customer	Oct. 31, 2021 USD ($) ft² customer	Oct. 31, 2020 USD ($) customer	Apr. 30, 2021 ft²
Property, Plant and Equipment [Line Items]
Number of customers | customer	3	4	3	4
Revenues	$ 16,236,000	$ 9,256,000	$ 26,743,000	$ 13,462,000
Customer outstanding receivables	$ 0	0	$ 0	0
Surface areas of land held | ft²	143,000		143,000
Area of land sold | ft²	143,000		143,000
Customer A
Property, Plant and Equipment [Line Items]
Revenues	$ 3,700,000	2,900,000	$ 6,700,000	4,800,000
Customer B
Property, Plant and Equipment [Line Items]
Revenues	2,400,000	2,600,000	3,700,000	2,600,000
Customer C
Property, Plant and Equipment [Line Items]
Revenues	$ 1,700,000	1,600,000	$ 3,400,000	2,400,000
Customer D
Property, Plant and Equipment [Line Items]
Revenues		$ 1,450,000		$ 2,000,000
Land sale revenue
Property, Plant and Equipment [Line Items]
Number of customers | customer	3		3	4
Warehouse and Office Buildings
Property, Plant and Equipment [Line Items]
Surface areas of land held | ft²					143,000
Area of land sold | ft²	143,000		143,000