DISCONTINUED OPERATIONS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2012	Oct. 31, 2011
DISCONTINUED OPERATIONS [Abstract]
Number Of Condominium Units Sold			2
Number of multi-family residential properties sold			2
REVENUE
Real estate rentals	$ 53,389	$ 49,371	$ 104,719	$ 97,804
Tenant reimbursement	11,554	10,829	22,210	21,560
TOTAL REVENUE	64,943	60,200	126,929	119,364
EXPENSES
Depreciation/amortization related to real estate investments	15,707	14,116	31,096	28,190
Utilities	4,859	4,848	9,057	8,792
Maintenance	6,511	6,888	13,853	13,653
Real estate taxes	8,281	7,624	16,628	15,381
Insurance	954	773	1,862	1,638
Property management expenses	4,199	5,394	8,245	10,705
Other expenses	513	835	1,032	1,150
Amortization related to non-real estate investments	799	758	1,632	1,492
TOTAL EXPENSES	43,884	43,340	87,562	85,286
Interest expense	(16,300)	(16,193)	(32,723)	(31,978)
Interest income	88	37	106	90
Gain on sale of discontinued operations			2,680	589
INCOME FROM DISCONTINUED OPERATIONS	2,785	611	2,754	598
Discontinued Operations [Member]
REVENUE
Real estate rentals	317	449	751	916
Tenant reimbursement	0	39	0	36
TOTAL REVENUE	317	488	751	952
EXPENSES
Depreciation/amortization related to real estate investments	50	77	114	169
Utilities	30	52	63	106
Maintenance	44	74	127	137
Real estate taxes	32	52	75	98
Insurance	9	12	23	24
Property management expenses	51	74	112	144
TOTAL EXPENSES	216	341	514	678
Interest expense	(69)	(125)	(163)	(265)
Income from discontinued operations before gain on sale	32	22	74	9
Gain on sale of discontinued operations	2,753	589	2,680	589
INCOME FROM DISCONTINUED OPERATIONS	$ 2,785	$ 611	$ 2,754	$ 598