MORTGAGES PAYABLE AND LINE OF CREDIT (Details) (USD $)	6 Months Ended
	Oct. 31, 2013	Nov. 30, 2013	Apr. 30, 2013
MORTGAGES PAYABLE AND LINE OF CREDIT [Abstract]
Interest rates on mortgages payable range, minimum (in hundredths)	2.51%
Interest rates on mortgages payable range, maximum (in hundredths)	8.25%
Mortgages maturity date range, end	Jul. 01, 2036
Fixed rate mortgages	$ 1,000,000,000		$ 1,000,000,000
Variable rate mortgages	8,400,000		26,200,000
Weighted average rate of interest on mortgage debt (in hundredths)	5.50%		5.55%
Aggregate amount of required future principal payments on mortgages payable [Abstract]
2014 (remainder)	29,907,000
2015	92,123,000
2016	92,596,000
2017	218,586,000
2018	64,798,000
Thereafter	523,160,000
Total payments	1,021,170,000		1,049,206,000
Long-term Debt, Percentage Bearing Fixed Interest, Amount	1,000,000,000		1,000,000,000
Lending commitments	60,000,000
Number of properties securing line of credit	23
Line of credit, current interest rate (in hundredths)	5.15%
Line of credit, minimum outstanding principal balance	10,000,000
Borrowed amount	10,000,000
Minimum depository accounts	6,000,000
Non-interest bearing account	1,500,000
Revolving credit facility, amended		$ 72,000,000