DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017
Debt Instrument [Line Items]
Carrying principal value	$ 706,140	$ 786,030
Fixed Rate Mortgages Payable [Member]
Debt Instrument [Line Items]
Carrying principal value	$ 489,401	629,535
Weighted average maturity in years	6 years 3 months 18 days
Variable Rate Mortgages Payable [Member]
Debt Instrument [Line Items]
Carrying principal value	$ 22,739	$ 57,708
Weighted average maturity in years	3 years 3 months 18 days
Mortgages [Member]
Debt Instrument [Line Items]
Weighted average interest rate	4.69%	4.71%
Construction Loans [Member]
Debt Instrument [Line Items]
Carrying principal value	$ 0	$ 41,737
Weighted average interest rate	0.00%	3.27%
Unsecured Debt [Member]
Debt Instrument [Line Items]
Carrying principal value	$ 194,000	$ 57,050
Unsecured Debt [Member] | Line of Credit [Member]
Debt Instrument [Line Items]
Carrying principal value	$ 124,000	$ 57,050
Weighted average maturity in years	3 years
Weighted average interest rate	3.35%	2.67%
Unsecured Debt [Member] | Medium-term Notes [Member]
Debt Instrument [Line Items]
Carrying principal value	$ 70,000	$ 0
Weighted average maturity in years	4 years
Weighted average interest rate	3.86%	0.00%