MORTGAGES PAYABLE AND LINE OF CREDIT, Mortgages Payable (Details) $ in Thousands	9 Months Ended
	Jan. 31, 2016 USD ($) Loan	Apr. 30, 2015 USD ($)
Aggregate amount of required future principal payments on mortgages payable [Abstract]
Total payments	$ 761,645	$ 668,112
Mortgages Payable [Member]
Mortgages Payable [Abstract]
Interest rates on mortgages payable range, minimum	2.73%
Interest rates on mortgages payable range, maximum	7.94%
Mortgages maturity date	Jul. 01, 2036
Number of loans in default | Loan	0
Fixed rate mortgages	$ 671,600	629,800
Variable rate mortgages	$ 90,000	$ 38,300
Weighted average rate of interest on mortgage debt, excluding HFS	4.80%	4.95%
Aggregate amount of required future principal payments on mortgages payable [Abstract]
2016 (remainder)	$ 46,710
2017	43,543
2018	41,229
2019	116,598
2020	111,490
Thereafter	402,075
Total payments	761,645
Mortgages Payable [Member] | Assets Held for Sale [Member]
Mortgages Payable [Abstract]
Minimum future principal payments	$ 10,700