MORTGAGES PAYABLE AND CONSTRUCTION DEBT (Details) $ in Thousands	6 Months Ended
	Oct. 31, 2016 USD ($) loan	Apr. 30, 2016 USD ($)
Aggregate amount of required future principal payments on mortgages payable [Abstract]
Total payments	$ 779,568	$ 812,393
Mortgages Payable [Member]
Debt Instrument [Line Items]
Interest rates on mortgages payable range, minimum (in hundredths)	2.49%
Interest rates on mortgages payable range, maximum (in hundredths)	7.94%
Mortgages maturity date range, end	Jul. 01, 2036
Number of loans in default | loan	0
Fixed rate mortgages	$ 617,700	689,300
Variable rate mortgages	$ 226,900	$ 196,800
Weighted average interest rate (in hundredths)	4.55%	4.54%
Mortgage indebtness	$ 844,600
Aggregate amount of required future principal payments on mortgages payable [Abstract]
2017 (remainder)	73,122
2018	64,747
2019	141,952
2020	94,259
2021	154,262
Thereafter	255,448
Total payments	783,790
Mortgages Payable [Member] | Assets Held for Sale [Member]
Aggregate amount of required future principal payments on mortgages payable [Abstract]
2017 (remainder)	45,684
2018	819
2019	2,326
2020	668
2021	710
Thereafter	10,588
Total payments	$ 60,795