GENERAL AND ADMINISTRATIVE EXPENSES - Additional Information (Details) - USD ($)	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
General and Administrative Expense, Disclosure [Line Items]
Lump sum payouts of pension benefits to former employees		$ 7,280,000
Non-cash pre-tax pension settlement loss	$ 7,280,000	2,929,000
Impairment charges on other assets		5,046,000
Amount of settlement received	$ 650,000	625,000
Settlement Agreement
General and Administrative Expense, Disclosure [Line Items]
Amount of settlement received		$ 625,000