ACQUISITIONS AND DISPOSITIONS (Details) (USD $)	3 Months Ended
	Jul. 31, 2012		Jul. 31, 2011
Significant Acquisitions and Disposals [Line Items]
Transaction costs expensed during the period	$ 73,000		$ 0
Acquisitions and development projects placed in service [Abstract]
Land	4,320,000
Buildings	47,328,000
Intangible assets	752,000
Acquisition costs	52,400,000
Dispositions [Abstract]
Sales price	955,000
Book value and sales cost	1,028,000
Gain/(Loss)	(73,000)
Multi-Family Residential [Member]
Acquisitions and development projects placed in service [Abstract]
Number of apartment units	4,522
Villa West - Topeka, KS [Member]
Significant Acquisitions and Disposals [Line Items]
Area of land (in acres)	18.3
Cash paid for acquisition of property	5,200,000
Assumed debt	12,500,000
Villa West - Topeka, KS [Member] | Multi-Family Residential [Member]
Acquisitions and development projects placed in service [Abstract]
Date acquired	May 08, 2012
Land	1,590,000
Buildings	15,760,000
Intangible assets	300,000
Acquisition costs	17,650,000
Number of apartment units	308
Colony - Lincoln, NE [Member]
Significant Acquisitions and Disposals [Line Items]
Area of land (in acres)	14.7
Cash paid for acquisition of property	14,200,000
Noncontrolling Interest in Operating Partnerships	3,300,000
Colony - Lincoln, NE [Member] | Multi-Family Residential [Member]
Acquisitions and development projects placed in service [Abstract]
Date acquired	Jun. 04, 2012
Land	1,515,000
Buildings	15,731,000
Intangible assets	254,000
Acquisition costs	17,500,000
Number of apartment units	232
Lakeside Village - Lincoln, NE [Member]
Significant Acquisitions and Disposals [Line Items]
Area of land (in acres)	11.5
Cash paid for acquisition of property	13,800,000
Noncontrolling Interest in Operating Partnerships	3,500,000
Lakeside Village - Lincoln, NE [Member] | Multi-Family Residential [Member]
Acquisitions and development projects placed in service [Abstract]
Date acquired	Jun. 04, 2012
Land	1,215,000
Buildings	15,837,000
Intangible assets	198,000
Acquisition costs	17,250,000
Number of apartment units	208
Quarry Ridge II - Rochester, MN [Member]
Significant Acquisitions and Disposals [Line Items]
Number of buildings	4
Project costs incurred to date	17,300,000
Estimated cost of construction	15,600,000
Acquisitions and development projects placed in service [Abstract]
Project costs incurred to date	17,300,000
Williston Garden Buildings 3 and 4 - Williston, ND [Member]
Significant Acquisitions and Disposals [Line Items]
Interest in joint venture (in hundredths)	60.00%
Project costs incurred to date	19,500,000
Acquisitions and development projects placed in service [Abstract]
Project costs incurred to date	19,500,000
Georgetown Condos 5 and 6 [Member]
Dispositions [Abstract]
Sales price	330,000
Book value and sales cost	336,000
Gain/(Loss)	(6,000)
Kentwood Thomasville - Kentwood, MI [Member] | Commercial Retail [Member]
Acquisitions and development projects placed in service [Abstract]
Area of a real estate property (in square feet)	16,080
Dispositions [Abstract]
Sales price	625,000
Book value and sales cost	692,000
Gain/(Loss)	(67,000)
Area of a real estate property (in square feet)	16,080
Development Projects Placed in Service [Member]
Acquisitions and development projects placed in service [Abstract]
Land	0		0
Buildings	7,701,000		764,000
Intangible assets	0		0
Acquisition costs	7,701,000		764,000
Development Projects Placed in Service [Member] | Quarry Ridge II - Rochester, MN [Member] | Multi-Family Residential [Member]
Significant Acquisitions and Disposals [Line Items]
Project costs incurred to date	16,500,000
Acquisitions and development projects placed in service [Abstract]
Date acquired	Jun. 29, 2012	[1]
Land	0	[1]
Buildings	3,543,000	[1]
Intangible assets	0	[1]
Acquisition costs	3,543,000	[1]
Number of apartment units	159
Additional construction costs during the period	13,000,000
Project costs incurred to date	16,500,000
Development Projects Placed in Service [Member] | Williston Garden Buildings 3 and 4 - Williston, ND [Member] | Multi-Family Residential [Member]
Significant Acquisitions and Disposals [Line Items]
Project costs incurred to date	16,200,000
Acquisitions and development projects placed in service [Abstract]
Date acquired	Jul. 31, 2012	[2]
Land	0	[2]
Buildings	4,158,000	[2]
Intangible assets	0	[2]
Acquisition costs	4,158,000	[2]
Number of apartment units	73
Additional construction costs during the period	12,000,000
Project costs incurred to date	16,200,000
Development Projects Placed in Service [Member] | Jamestown Buffalo Mall - Jamestown, ND [Member] | Multi-Family Residential [Member]
Acquisitions and development projects placed in service [Abstract]
Acquisition costs			764,000	[3]
Development Projects Placed in Service [Member] | Jamestown Buffalo Mall - Jamestown, ND [Member] | Commercial Retail [Member]
Significant Acquisitions and Disposals [Line Items]
Project costs incurred to date			2,200,000
Acquisitions and development projects placed in service [Abstract]
Date acquired			Jun. 15, 2011	[3]
Land			0	[3]
Buildings			764,000	[3]
Intangible assets			0	[3]
Area of a real estate property (in square feet)			19,037
Additional construction costs during the period			1,400,000
Project costs incurred to date			$ 2,200,000
Dispositions [Abstract]
Area of a real estate property (in square feet)			19,037

[1] (1) Development property placed in service June 29, 2012. Additional costs paid in fiscal years 2012 and 2011, and land acquired in fiscal year 2007, totaled $13.0 million, for a total project cost at July 31, 2012 of $16.5 million.

[2] (2) Development property placed in service July 31, 2012. Buildings 1 and 2 were placed in service in fiscal year 2012. Additional costs paid in fiscal year 2012 totaled $12.0 million, for a total project cost at July 31, 2012 of $16.2 million.

[3] (1) Construction project placed in service June 15, 2011. Additional costs incurred in fiscal year 2011 totaled $1.4 million, for a total project cost at July 31, 2011 of $2.2 million.