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REVENUES - Additional Information (Details)
 3 Months Ended 9 Months Ended
Jan. 31, 2021
a
customer
Jan. 31, 2020
customer
Jan. 31, 2021
a
customer
USD ($)
Jan. 31, 2020
customer
Apr. 30, 2020
a
Property, Plant and Equipment [Line Items]          
Surface areas of land held 6,000   6,000   6,000
Minerals and mineral rights          
Property, Plant and Equipment [Line Items]          
Surface areas of land held 55,000   55,000    
Home sale revenues          
Property, Plant and Equipment [Line Items]          
Number of customers 6   7    
New Mexico          
Property, Plant and Equipment [Line Items]          
Surface areas of land held 12,000   12,000   12,000
New Mexico | Land sale revenues          
Property, Plant and Equipment [Line Items]          
Number of customers | customer 4 4 4 4