DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2018	Apr. 30, 2018
Debt Instrument [Line Items]
Carrying principal balance	$ 663,914	$ 706,140
Weighted Average Maturity in Years at October 31, 2018	4 years 6 months 94 days
Fixed Rate Mortgages Payable [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 449,414	489,401
Weighted Average Maturity in Years at October 31, 2018	4 years 6 months
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	4.59%	4.69%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 214,500	$ 194,000
Unsecured Debt [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 69,500	$ 124,000
Weighted Average Maturity in Years at October 31, 2018	3 years 9 months 18 days
Weighted average interest rate	3.72%	3.35%
Term Loan A [Member] | Unsecured Debt [Member] | Medium-term Notes [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 70,000	$ 70,000
Weighted Average Maturity in Years at October 31, 2018	5 years 2 months 12 days
Weighted average interest rate	3.75%	3.86%
Term Loan B [Member] | Unsecured Debt [Member] | Medium-term Notes [Member]
Debt Instrument [Line Items]
Carrying principal balance	$ 75,000	$ 0
Weighted Average Maturity in Years at October 31, 2018	6 years 9 months 18 days
Weighted average interest rate	4.60%