DISCONTINUED OPERATIONS (Details) (USD $)	3 Months Ended								12 Months Ended
	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
REVENUE
Real estate rentals									$ 219,921,000	$ 204,719,000	$ 188,299,000
Tenant reimbursement									45,561,000	43,339,000	40,372,000
TOTAL REVENUE	66,983,000	67,629,000	65,772,000	65,098,000	64,184,000	63,080,000	61,864,000	58,930,000	265,482,000	248,058,000	228,671,000
EXPENSES
Depreciation/amortization related to real estate investments									67,592,000	59,306,000	53,690,000
Utilities									21,864,000	18,792,000	17,106,000
Maintenance									31,158,000	28,340,000	25,530,000
Real estate taxes									32,982,000	32,182,000	29,349,000
Insurance									5,165,000	3,734,000	3,343,000
Property management expenses									16,961,000	15,003,000	18,164,000
Other property expenses									357,000	1,008,000	(142,000)
Other expenses									2,132,000	2,173,000	1,898,000
Amortization related to non-real estate investments									3,326,000	3,027,000	2,960,000
TOTAL EXPENSES									234,846,000	172,059,000	159,279,000
Operating income									33,116,000	81,083,000	69,666,000
Interest expense									(59,142,000)	(61,154,000)	(61,801,000)
Interest income									1,908,000	222,000	148,000
Other income									779,000	526,000	631,000
INCOME (LOSS) FROM DISCONTINUED OPERATIONS									6,450,000	9,295,000	1,062,000
Asset and Liability Data
Total assets	0				72,631,000				0	72,631,000
Total liabilities	0				(1,335,000)				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									2	3
Commercial Office [Member] | Grand Chute, Wisconsin [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									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										1
Commercial Industrial [Member] | Kentwood, Michigan [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									12
Commercial 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									3	1	1
Number of properties classified as held for sale											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										4	8
Number of properties classified as held for sale											8
Discontinued Operations [Member]
REVENUE
Real estate rentals									3,173,000	10,068,000	10,702,000
Tenant reimbursement									1,302,000	3,099,000	2,619,000
TOTAL REVENUE									4,475,000	13,167,000	13,321,000
EXPENSES
Depreciation/amortization related to real estate investments									920,000	3,169,000	3,418,000
Utilities									164,000	447,000	561,000
Maintenance									299,000	1,029,000	1,070,000
Real estate taxes									951,000	2,276,000	2,428,000
Insurance									97,000	218,000	211,000
Property management expenses									222,000	520,000	759,000
Other property expenses									0	16,000	4,000
Other expenses									0	0	67,000
Amortization related to non-real estate investments									90,000	247,000	256,000
Impairment of real estate investments									1,860,000	305,000	428,000
TOTAL EXPENSES									4,603,000	8,227,000	9,202,000
Operating income									(128,000)	4,940,000	4,119,000
Interest expense									(421,000)	(2,532,000)	(3,429,000)
Other income									0	2,000	23,000
Income (loss) from discontinued operations before gain on sale									(549,000)	2,410,000	713,000
Gain on sale of discontinued operations									6,999,000	6,885,000	349,000
INCOME (LOSS) FROM DISCONTINUED OPERATIONS									6,450,000	9,295,000	1,062,000
Property Sale Data
Sales price									80,883,000	26,273,000	3,237,000
Net book value and sales costs									(73,884,000)	(19,388,000)	(2,888,000)
Gain on sale of discontinued operations									6,999,000	6,885,000	349,000
Discontinued Operations [Member] | Multi-Family Residential [Member]
EXPENSES
INCOME (LOSS) FROM DISCONTINUED OPERATIONS									(99,000)	3,712,000	100,000
Discontinued Operations [Member] | Commercial Office [Member]
EXPENSES
INCOME (LOSS) FROM DISCONTINUED OPERATIONS									(1,794,000)	314,000	52,000
Discontinued Operations [Member] | Commercial Healthcare [Member]
EXPENSES
INCOME (LOSS) FROM DISCONTINUED OPERATIONS									0	3,416,000	(465,000)
Discontinued Operations [Member] | Commercial Industrial [Member]
EXPENSES
INCOME (LOSS) FROM DISCONTINUED OPERATIONS									8,923,000	2,118,000	1,127,000
Discontinued Operations [Member] | Commercial Retail [Member]
EXPENSES
INCOME (LOSS) FROM DISCONTINUED OPERATIONS									$ (580,000)	$ (265,000)	$ 248,000