DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2018	Apr. 30, 2018
Debt Instrument [Line Items]
Carrying principal balance	$ 666,555	$ 706,140
Weighted Average Maturity in Years	4 years 11 months 3 days
Fixed Rate Mortgages Payable [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 466,555	489,401
Weighted Average Maturity in Years	5 years 4 months 24 days
Variable Rate Mortgages Payable [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 0	$ 22,739
Mortgages [Member]
Debt Instrument [Line Items]
Weighted average interest rate	4.65%	4.69%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 200,000	$ 194,000
Unsecured Debt [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 130,000	$ 124,000
Weighted Average Maturity in Years	3 years
Weighted average interest rate	3.83%	3.35%
Unsecured Debt [Member] | Medium-term Notes [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 70,000	$ 70,000
Weighted Average Maturity in Years	4 years
Weighted average interest rate	3.86%	3.86%