ACQUISITIONS, DEVELOPMENT PROJECTS PLACED IN SERVICE AND DISPOSITIONS, DEVELOPMENT PROJECTS PLACED IN SERVICE (Details) - Development Projects Placed in Service [Member] - USD ($)		12 Months Ended
		Apr. 30, 2017		Apr. 30, 2016	Apr. 30, 2015
Business Acquisition [Line Items]
Land		$ 6,455,000	[1]	$ 9,119,000
Building		96,423,000	[1]	202,716,000
Development cost		$ 102,878,000	[1]	211,835,000
Multi-Family Residential [Member]
Business Acquisition [Line Items]
Land				5,620,000
Building				146,111,000
Development cost				151,731,000
Multi-Family Residential [Member] | 71 France - Edina, MN [Member]
Business Acquisition [Line Items]
Date placed in service	[1]	May 01, 2016
Land	[1]	$ 4,721,000
Building	[1]	67,641,000
Development cost	[1]	72,362,000
Development costs paid		1,500,000		70,900,000
Project costs incurred to date		$ 72,400,000
Interest in joint venture (in hundredths)		52.60%
Multi-Family Residential [Member] | Monticello Crossings - Monticello, MN
Business Acquisition [Line Items]
Date placed in service	[1]	Mar. 01, 2017
Land	[1]	$ 1,734,000
Building	[1]	28,782,000
Development cost	[1]	30,516,000
Development costs paid		15,000,000		$ 15,500,000
Project costs incurred to date		$ 30,500,000
Multi-Family Residential [Member] | 72 unit - Chateau II - Minot, ND [Member]
Business Acquisition [Line Items]
Date placed in service				Jun. 01, 2015
Land				$ 240,000
Building				14,408,000
Development cost				14,648,000
Development costs paid				2,300,000	$ 12,300,000
Project costs incurred to date				$ 14,600,000
Multi-Family Residential [Member] | Renaissance Heights - Williston, ND [Member]
Business Acquisition [Line Items]
Date placed in service	[2]			Jul. 27, 2015
Land	[2]			$ 3,080,000
Building	[2]			59,434,000
Development cost	[2]			62,514,000
Development costs paid				4,800,000	57,700,000
Project costs incurred to date				$ 62,500,000
Interest in joint venture (in hundredths)		86.60%
Multi-Family Residential [Member] | Deer Ridge - Jamestown, ND
Business Acquisition [Line Items]
Date placed in service				Feb. 22, 2016
Land				$ 700,000
Building				24,137,000
Development cost				24,837,000
Development costs paid				10,500,000	14,300,000
Project costs incurred to date				$ 24,800,000
Multi-Family Residential [Member] | Cardinal Point - Grand Forks, ND
Business Acquisition [Line Items]
Date placed in service				Mar. 18, 2016
Land				$ 1,600,000
Building				48,132,000
Development cost				49,732,000
Development costs paid				26,700,000	23,000,000
Project costs incurred to date				49,700,000
Healthcare [Member]
Business Acquisition [Line Items]
Land				2,610,000
Building				54,871,000
Development cost				$ 57,481,000
Healthcare [Member] | 57,624 sq ft Edina 6565 France SMC III - Edina, MN [Member]
Business Acquisition [Line Items]
Date placed in service				Jun. 01, 2015
Building				$ 33,041,000
Development cost				33,041,000
Development costs paid				12,200,000	20,800,000
Project costs incurred to date				$ 33,000,000
Healthcare [Member] | PrairieCare Medical - Brooklyn Park, MN [Member]
Business Acquisition [Line Items]
Date placed in service				Sep. 08, 2015
Land				$ 2,610,000
Building				21,830,000
Development cost				24,440,000
Development costs paid				7,100,000	17,300,000
Project costs incurred to date				$ 24,400,000
Other Member | Minot Southgate Retail - Minot, ND [Member]
Business Acquisition [Line Items]
Date placed in service				Oct. 01, 2015
Land				$ 889,000
Building				1,734,000
Development cost				2,623,000
Development costs paid				500,000	$ 2,100,000
Project costs incurred to date				$ 2,600,000

[1] Development projects that are placed in service in phases are excluded from this table until the entire project has been placed in service. See Note 15 for additional information on the 71 France project, which was partially placed in service during the fiscal year ended April 30, 2016.

[2] Development projects that are placed in service in phases are excluded from this table until the entire project has been placed in service. See Note 15 for additional information on the 71 France project, which was partially placed in service during the fiscal year ended April 30, 2016.Costs paid in prior fiscal years totaled $12.3 million. Additional costs incurred in fiscal year 2016 totaled $2.3 million, for a total project cost at April 30, 2016 of $14.6 million. Costs paid in prior fiscal years totaled $57.7 million. Additional costs incurred in fiscal year 2016 totaled $4.8 million, for a total project cost at April 30, 2016 of $62.5 million. The project is owned by a joint venture entity in which we currently have an approximately 86.6% interest. The joint venture is consolidated in our financial statements. Costs paid in prior fiscal years totaled $14.3 million. Additional costs incurred in fiscal year 2016 totaled $10.5 million, for a total project cost at April 30, 2016 of $24.8 million. Costs paid in prior fiscal years totaled $23.0 million. Additional costs incurred in fiscal year 2016 totaled $26.7 million, for a total project cost at April 30, 2016 of $49.7 million. Costs paid in prior fiscal years totaled $20.8 million. Additional costs incurred in fiscal year 2016 totaled $12.2 million, for a total project cost at April 30, 2016 of $33.0 million. Costs paid in prior fiscal years totaled $17.3 million. Additional costs incurred in fiscal year 2016 totaled $7.1 million, for a total project cost at April 30, 2016 of $24.4 million.Costs paid in prior fiscal years totaled $2.1 million. Additional costs incurred in fiscal year 2016 totaled approximately $500,000, for a total project cost at April 30, 2016 of $2.6 million.