DISCONTINUED OPERATIONS (Details)	3 Months Ended								12 Months Ended
	Apr. 30, 2015 USD ($)	Jan. 31, 2015 USD ($)	Oct. 31, 2014 USD ($)	Jul. 31, 2014 USD ($)	Apr. 30, 2014 USD ($)	Jan. 31, 2014 USD ($)	Oct. 31, 2013 USD ($)	Jul. 31, 2013 USD ($)	Apr. 30, 2015 USD ($)	Apr. 30, 2014 USD ($) Property	Apr. 30, 2013 USD ($) Property	Apr. 30, 2012 Property
REVENUE
Real estate rentals									$ 235,852,000	$ 219,921,000	$ 204,719,000
Tenant reimbursement									43,818,000	45,561,000	43,339,000
TOTAL REVENUE	$ 70,759,000	$ 72,916,000	$ 70,885,000	$ 68,630,000	$ 67,806,000	$ 68,433,000	$ 65,772,000	$ 65,098,000	283,190,000	267,109,000	248,058,000
EXPENSES
Depreciation/amortization related to real estate investments									67,112,000	67,592,000	59,306,000
Utilities									20,881,000	21,864,000	18,792,000
Maintenance									30,924,000	31,158,000	28,340,000
Real estate taxes									33,945,000	32,982,000	32,182,000
Insurance									5,839,000	5,165,000	3,734,000
Property management expenses									18,502,000	16,961,000	15,003,000
Other property expenses									906,000	357,000	1,008,000
Other expenses									2,010,000	2,132,000	2,173,000
Amortization related to non-real estate investments									3,495,000	3,326,000	3,027,000
Impairment of real estate investments									6,105,000	42,566,000
TOTAL EXPENSES									204,540,000	236,177,000	172,059,000
Operating (loss) income									78,650,000	33,412,000	81,083,000
Interest expense									(59,020,000)	(59,142,000)	(61,154,000)
Other income									723,000	483,000	526,000
Gain on sale of discontinued operations									6,093,000	6,948,000	6,885,000
INCOME FROM DISCONTINUED OPERATIONS									0	6,450,000	9,295,000
Property Sale Data
Gain on sale of discontinued operations									6,093,000	6,948,000	6,885,000
Asset and Liability Data
Total assets					0					0	72,631,000
Total liabilities					$ 0					$ 0	$ (1,335,000)
Multi-Family Residential [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties classified as discontinued operations | Property										2	3
Commercial Office [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties classified as discontinued operations | Property										3
Commercial Healthcare [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties classified as discontinued operations | Property											1
Commercial Industrial [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties classified as discontinued operations | Property										12
Retail [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties classified as discontinued operations | Property										3	1	1
Number of properties classified as held for sale | Property												1
Condominium Unit [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of real estate properties classified as discontinued operations | Property											4	8
Number of properties classified as held for sale | Property												8
Discontinued Operations [Member]
REVENUE
Real estate rentals										$ 3,173,000	$ 10,068,000
Tenant reimbursement										1,302,000	3,099,000
TOTAL REVENUE										4,475,000	13,167,000
EXPENSES
Depreciation/amortization related to real estate investments										920,000	3,169,000
Utilities										164,000	447,000
Maintenance										299,000	1,029,000
Real estate taxes										951,000	2,276,000
Insurance										97,000	218,000
Property management expenses										222,000	520,000
Other property expenses										0	16,000
Amortization related to non-real estate investments										90,000	247,000
Impairment of real estate investments									$ 0	1,860,000	305,000
TOTAL EXPENSES										4,603,000	8,227,000
Operating (loss) income										(128,000)	4,940,000
Interest expense										(421,000)	(2,532,000)
Other income										0	2,000
(Loss) income from discontinued operations before gain on sale										(549,000)	2,410,000
Gain on sale of discontinued operations										6,999,000	6,885,000
INCOME FROM DISCONTINUED OPERATIONS										6,450,000	9,295,000
Property Sale Data
Sales price										80,883,000	26,273,000
Net book value and sales costs										(73,884,000)	(19,388,000)
Gain on sale of discontinued operations										6,999,000	6,885,000
Discontinued Operations [Member] | Multi-Family Residential [Member]
EXPENSES
INCOME FROM DISCONTINUED OPERATIONS										(99,000)	3,712,000
Discontinued Operations [Member] | Commercial Office [Member]
EXPENSES
INCOME FROM DISCONTINUED OPERATIONS										(1,794,000)	314,000
Discontinued Operations [Member] | Commercial Healthcare [Member]
EXPENSES
INCOME FROM DISCONTINUED OPERATIONS										0	3,416,000
Discontinued Operations [Member] | Commercial Industrial [Member]
EXPENSES
INCOME FROM DISCONTINUED OPERATIONS										8,923,000	2,118,000
Discontinued Operations [Member] | Retail [Member]
EXPENSES
INCOME FROM DISCONTINUED OPERATIONS										$ (580,000)	$ (265,000)