DEBT (Details) $ in Thousands	6 Months Ended
	Oct. 31, 2017 USD ($) loan	Apr. 30, 2017 USD ($)
Aggregate amount of required future principal payments on mortgages payable [Abstract]
Total payments	$ 655,903	$ 661,960
Mortgages Payable [Member]
Debt Instrument [Line Items]
Mortgages maturity date range, end	Jul. 01, 2036
Number of loans in default | loan	0
Fixed rate mortgages	$ 593,900	629,500
Variable rate mortgages	$ 65,100	$ 57,700
Weighted average interest rate (in hundredths)	4.67%	4.71%
Mortgage indebtness	$ 659,000
Aggregate amount of required future principal payments on mortgages payable [Abstract]
2018 (remainder)	21,398
2019	100,313
2020	92,258
2021	128,352
2022	86,812
Thereafter	229,832
Total payments	$ 658,965
Mortgages Payable [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate on mortgages payable (in hundredths)	3.47%
Mortgages Payable [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate on mortgages payable (in hundredths)	6.66%