ACQUISITIONS, DEVELOPMENT PROJECTS PLACED IN SERVICE AND DISPOSITIONS, DEVELOPMENT PROJECTS PLACED IN SERVICE (Details) - USD ($)		12 Months Ended
		Apr. 30, 2016		Apr. 30, 2015		Apr. 30, 2014
Business Acquisition [Line Items]
Project costs incurred to date		$ 167,532,000
Development Projects Placed in Service [Member]
Business Acquisition [Line Items]
Land		9,119,000	[1]	$ 9,941,000	[2]
Building		202,716,000	[1]	114,548,000	[2]
Development cost		211,835,000	[1]	124,489,000	[2]
Development Projects Placed in Service [Member] | Multi-Family Residential [Member]
Business Acquisition [Line Items]
Land		5,620,000	[1]	8,949,000	[2]
Building		146,111,000	[1]	103,319,000	[2]
Development cost		$ 151,731,000	[1]	112,268,000	[2]
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | 72 unit - Chateau II - Minot, ND [Member]
Business Acquisition [Line Items]
Date placed in service	[1],[3]	Jun. 01, 2015
Land	[1],[3]	$ 240,000
Building	[1],[3]	14,408,000
Development cost	[1],[3]	14,648,000
Development costs paid		2,300,000		12,300,000
Project costs incurred to date		$ 14,600,000
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | 288 unit - Renaissance Heights - Williston, ND [Member]
Business Acquisition [Line Items]
Date placed in service	[1],[4]	Jul. 27, 2015
Land	[1],[4]	$ 3,080,000
Building	[1],[4]	59,434,000
Development cost	[1],[4]	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)		70.00%
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | 163 unit - Deer Ridge - Jamestown, ND
Business Acquisition [Line Items]
Date placed in service	[1]	Feb. 22, 2016
Land	[1]	$ 700,000
Building	[1]	24,137,000
Development cost	[1]	24,837,000
Development costs paid		10,500,000		14,300,000
Project costs incurred to date		$ 24,800,000
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | 251 unit - Cardinal Point - Grand Forks, ND
Business Acquisition [Line Items]
Date placed in service	[1]	Mar. 18, 2016
Land	[1]	$ 1,600,000
Building	[1]	48,132,000
Development cost	[1]	49,732,000
Development costs paid		26,700,000		$ 23,000,000
Project costs incurred to date		49,700,000
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | Dakota Commons - Williston, ND [Member]
Business Acquisition [Line Items]
Date placed in service	[2],[5]			Jul. 15, 2014
Land	[2],[5]			$ 823,000
Building	[2],[5]			9,596,000
Development cost	[2],[5]			10,419,000
Development costs paid				2,300,000		$ 8,100,000
Project costs incurred to date				$ 10,400,000
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | RED 20 - Minneapolis, MN [Member]
Business Acquisition [Line Items]
Date placed in service	[2],[6]			Nov. 21, 2014
Land	[2],[6]			$ 1,900,000
Building	[2],[6]			26,412,000
Development cost	[2],[6]			28,312,000
Development costs paid				16,100,000		12,200,000
Project costs incurred to date				$ 28,300,000
Interest in joint venture (in hundredths)				58.60%
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | Commons at Southgate - Minot, ND [Member]
Business Acquisition [Line Items]
Date placed in service	[2],[7]			Dec. 09, 2014
Land	[2],[7]			$ 3,691,000
Building	[2],[7]			31,351,000
Development cost	[2],[7]			35,042,000
Development costs paid				8,100,000		26,500,000
Project costs incurred to date				$ 35,000,000
Interest in joint venture (in hundredths)				52.90%
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | Cypress Court II - St. Cloud, MN [Member]
Business Acquisition [Line Items]
Date placed in service	[2],[8]			Jan. 01, 2015
Land	[2],[8]			$ 447,000
Building	[2],[8]			6,320,000
Development cost	[2],[8]			6,767,000
Development costs paid				5,500,000		1,200,000
Project costs incurred to date				$ 6,800,000
Interest in joint venture (in hundredths)				86.10%
Development Projects Placed in Service [Member] | Multi-Family Residential [Member] | Arcata - Golden Valley, MN [Member]
Business Acquisition [Line Items]
Date placed in service	[2],[9]			Jan. 01, 2015
Land	[2],[9]			$ 2,088,000
Building	[2],[9]			29,640,000
Development cost	[2],[9]			31,728,000
Development costs paid				19,100,000		$ 11,300,000
Project costs incurred to date				31,700,000
Development Projects Placed in Service [Member] | Healthcare [Member]
Business Acquisition [Line Items]
Land	[1]	2,610,000
Building	[1]	54,871,000
Development cost	[1]	$ 57,481,000
Development Projects Placed in Service [Member] | Healthcare [Member] | 57,624 sq ft Edina 6565 France SMC III - Edina, MN [Member]
Business Acquisition [Line Items]
Date placed in service	[1],[10]	Jun. 01, 2015
Building	[1],[10]	$ 33,041,000
Development cost	[1],[10]	33,041,000
Development costs paid		12,200,000		20,800,000
Project costs incurred to date		$ 33,000,000
Development Projects Placed in Service [Member] | Healthcare [Member] | 70,756 sq ft PrairieCare Medical - Brooklyn Park, MN [Member]
Business Acquisition [Line Items]
Date placed in service	[1],[11]	Sep. 08, 2015
Land	[1],[11]	$ 2,610,000
Building	[1],[11]	21,830,000
Development cost	[1],[11]	24,440,000
Development costs paid		7,100,000		17,300,000
Project costs incurred to date		$ 24,400,000
Development Projects Placed in Service [Member] | Other Member
Business Acquisition [Line Items]
Land	[2]			992,000
Building	[2]			11,229,000
Development cost	[2]			12,221,000
Development Projects Placed in Service [Member] | Other Member | 7,963 sq ft Minot Southgate Retail - Minot, ND [Member]
Business Acquisition [Line Items]
Date placed in service	[1],[12]	Oct. 01, 2015
Land	[1],[12]	$ 889,000
Building	[1],[12]	1,734,000
Development cost	[1],[12]	2,623,000
Development costs paid		500,000		$ 2,100,000
Project costs incurred to date		$ 2,600,000
Development Projects Placed in Service [Member] | Other Member | Roseville 3075 Long Lake Rd - Roseville, MN [Member]
Business Acquisition [Line Items]
Date placed in service	[2]			Feb. 02, 2015
Building	[2]			$ 9,036,000
Development cost	[2]			$ 9,036,000
Development Projects Placed in Service [Member] | Other Member | Minot Southgate Wells Fargo Bank - Minot, ND [Member]
Business Acquisition [Line Items]
Date placed in service	[2],[13]			Nov. 10, 2014
Land	[2],[13]			$ 992,000
Building	[2],[13]			2,193,000
Development cost	[2],[13]			3,185,000
Development costs paid				$ 3,200,000

[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 6 for additional information on the Renaissance Heights project, which was partially placed in service during the fiscal year 2014 and the twelve months ended April 30, 2015.

[3] 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.

[4] 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 70.0% interest. The joint venture is consolidated in our financial statements.

[5] Costs paid in prior fiscal years totaled $8.1 million. Additional costs paid in fiscal year 2015 totaled $2.3 million, for a total project cost at April 30, 2015 of $10.4 million.

[6] Costs paid in prior fiscal years totaled $12.2 million. Additional costs paid in fiscal year 2015 totaled $16.1 million, for a total project cost at April 30, 2015 of $28.3 million. The project is owned by a joint venture entity in which we have an approximately 58.6% interest. The joint venture is consolidated in our financial statements.

[7] Costs paid in prior fiscal years totaled $26.5 million, respectively. Additional costs paid in fiscal year 2015 totaled $8.1 million, for a total project cost at April 30, 2015 of $35.0 million. The project is owned by a joint venture entity in which we had an approximately 52.9% interest at April 30, 2015. The joint venture is consolidated in our financial statements.

[8] Costs paid in prior fiscal years totaled $1.2 million. Additional costs paid in fiscal year 2015 totaled $5.5 million, for a total project cost at April 30, 2015 of $6.8 million. The project is owned by a joint venture entity in which we have an approximately 86.1% interest. The joint venture is consolidated in our financial statements.

[9] Costs paid in prior fiscal years totaled $11.3 million, respectively. Additional costs paid in fiscal year 2015 totaled $19.1 million, for a total project cost at April 30, 2015 of $31.7 million.

[10] 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.

[11] 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.

[12] 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.

[13] Costs paid in fiscal year 2015 totaled $3.2 million, including land acquired in fiscal year 2013.