ACQUISITIONS, DEVELOPMENT PROJECTS PLACED IN SERVICE AND DISPOSITIONS, PROPERTY DISPOSITIONS (Details) $ in Thousands			12 Months Ended
		Jan. 29, 2016 USD ($) property	Apr. 30, 2016 USD ($) property	Apr. 30, 2015 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale price			$ 536,728	$ 88,867
Book value and sales cost			466,835	78,300
Gain/(Loss)			69,893	$ 10,567
Sale price, net of properties transferred			$ 414,100
Multi-Family Residential [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property			8
Multi-Family Residential [Member] | 391 unit - St. Cloud Student Housing Portfolio - St. Cloud, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			Mar. 24, 2016
Sale price			$ 5,615
Book value and sales cost			5,647
Gain/(Loss)			$ (32)
Multi-Family Residential [Member] | 83 unit - Lancaster - St. Cloud, MN
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Sep. 22, 2014
Sale price				$ 4,451
Book value and sales cost				3,033
Gain/(Loss)				$ 1,418
Healthcare [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property			2
Healthcare [Member] | 61,758 sq ft Nebraska Orthopaedic Hospital - Omaha, NE
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			Apr. 01, 2016
Sale price			$ 24,494
Book value and sales cost			16,512
Gain/(Loss)			7,982
Healthcare [Member] | Jamestown Medical Office Building Jamestown ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Feb. 05, 2015
Sale price				$ 12,819
Book value and sales cost				8,710
Gain/(Loss)				4,109
Other [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale price			506,599	70,769
Book value and sales cost			444,655	65,729
Gain/(Loss)			$ 61,944	$ 5,040
Other [Member] | 117,144 sq ft Thresher Square - Minneapolis, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			May 18, 2015
Sale price			$ 7,000
Book value and sales cost			7,175
Gain/(Loss)			$ (175)
Other [Member] | 2,549,222 sq ft Office Sale Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed	[1]		Aug. 03, 2015
Sale price	[1]		$ 250,000
Book value and sales cost	[1]		231,908
Gain/(Loss)	[1]		$ 18,092
Other [Member] | 420,216 sq ft Mendota Office Center Portfolio - Mendota Heights, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed	[2]		Aug. 12, 2015
Sale price	[2]		$ 40,000
Book value and sales cost	[2]		41,574
Gain/(Loss)	[2]		$ (1,574)
Other [Member] | 1,027,208 sq ft Retail Sale Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed	[3]		Sep. 30, 2015
Sale price	[3]		$ 78,960
Book value and sales cost	[3]		72,000
Gain/(Loss)	[3]		$ 6,960
Other [Member] | 48,700 sq ft Eden Prairie 6101 Blue Circle Drive - Eden Prairie, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			Oct. 19, 2015
Sale price			$ 2,900
Book value and sales cost			2,928
Gain/(Loss)			$ (28)
Other [Member] | Burnsville 1 Strip Center - Burnsville, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			Dec. 23, 2015
Sale price			$ 1,300
Book value and sales cost			913
Gain/(Loss)			$ 387
Other [Member] | Pine City C-Store - Pine City, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			Jan. 08, 2016
Sale price			$ 300
Book value and sales cost			355
Gain/(Loss)			$ (55)
Other [Member] | Minot Plaza - Minot, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			Jan. 19, 2016
Sale price			$ 1,854
Book value and sales cost			393
Gain/(Loss)			$ 1,461
Other [Member] | 937,518 sq ft 9-Building Office Portfolio [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed	[4],[5]		Jan. 29, 2016
Sale price	[4],[5]		$ 122,610
Book value and sales cost	[4],[5]		86,154
Gain/(Loss)	[4],[5]		$ 36,456
Number of properties transferred | property		9
Non-recourse loan		$ 122,600
Estimated fair value of properties transferred		$ 89,300
Other [Member] | 3,702 sq ft Arrowhead First International Bank - Minot, ND
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			Apr. 06, 2016
Sale price			$ 1,675
Book value and sales cost			1,255
Gain/(Loss)			$ 420
Other [Member] | Dewey Hill - Edina, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				May 19, 2014
Sale price				$ 3,100
Book value and sales cost				3,124
Gain/(Loss)				$ (24)
Other [Member] | Wirth Corporate Center - Golden Valley, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Aug. 29, 2014
Sale price				$ 4,525
Book value and sales cost				4,695
Gain/(Loss)				$ (170)
Other [Member] | Northgate I - Maple Grove, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Dec. 01, 2014
Sale price				$ 7,200
Book value and sales cost				6,881
Gain/(Loss)				$ 319
Other [Member] | Northgate II - Maple Grove, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Mar. 02, 2015
Sale price				$ 2,725
Book value and sales cost				1,727
Gain/(Loss)				$ 998
Other [Member] | Burnsville Bluffs II - Burnsville, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Mar. 25, 2015
Sale price				$ 1,245
Book value and sales cost				2,245
Gain/(Loss)				$ (1,000)
Other [Member] | Plymouth I - Plymouth, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Mar. 25, 2015
Sale price				$ 1,985
Book value and sales cost				1,492
Gain/(Loss)				$ 493
Other [Member] | Plymouth II - Plymouth, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Mar. 25, 2015
Sale price				$ 1,625
Book value and sales cost				1,356
Gain/(Loss)				$ 269
Other [Member] | Plymouth III - Plymouth, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Mar. 25, 2015
Sale price				$ 2,500
Book value and sales cost				1,977
Gain/(Loss)				$ 523
Other [Member] | Plymouth IV & V - Plymouth, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Mar. 25, 2015
Sale price				$ 12,910
Book value and sales cost				11,706
Gain/(Loss)				$ 1,204
Other [Member] | Southeast Tech Center - Eagan, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Mar. 25, 2015
Sale price				$ 3,300
Book value and sales cost				4,196
Gain/(Loss)				$ (896)
Other [Member] | Whitewater Plaza - Minnetonka, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Mar. 25, 2015
Sale price				$ 3,035
Book value and sales cost				4,625
Gain/(Loss)				$ (1,590)
Other [Member] | 2030 Cliff Road - Eagan, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Apr. 21, 2015
Sale price				$ 950
Book value and sales cost				834
Gain/(Loss)				$ 116
Other [Member] | Jamestown Medical Office Building Jamestown ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Feb. 05, 2015
Sale price				$ 12,819
Book value and sales cost				8,710
Gain/(Loss)				$ 4,109
Other [Member] | Eagan 2785 & 2795 - Eagan, MN [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Jul. 15, 2014
Sale price				$ 3,600
Book value and sales cost				5,393
Gain/(Loss)				$ (1,793)
Other [Member] | Weston Retail - Weston, WI [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Jul. 28, 2014
Book value and sales cost				$ 1,176
Gain/(Loss)				$ (1,176)
Other [Member] | Kalispell Retail - Kalispell, MT [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Oct. 15, 2014
Sale price				$ 1,230
Book value and sales cost				1,229
Gain/(Loss)				$ 1
Other [Member] | Fargo Express Center & SC Pad - Fargo, ND [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Nov. 18, 2014
Sale price				$ 2,843
Book value and sales cost				2,211
Gain/(Loss)				$ 632
Other [Member] | Weston Walgreens - Weston, WI [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Feb. 27, 2015
Sale price				$ 5,177
Book value and sales cost				2,152
Gain/(Loss)				3,025
Office [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property			40
Number of properties transferred | property			9
Retail [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties sold | property			18
Unimproved Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale price				828
Book value and sales cost				$ 828
Number of properties sold | property			3
Unimproved Land [Member] | River Falls Unimproved Land - River Falls, WI
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed			Apr. 06, 2016
Sale price			$ 20
Book value and sales cost			21
Gain/(Loss)			$ (1)
Unimproved Land [Member] | Kalispell Unimproved - Kalispell, MT [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Oct. 15, 2014
Sale price				$ 670
Book value and sales cost				$ 670
Unimproved Land [Member] | Weston - Weston, WI [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Date disposed				Feb. 17, 2015
Sale price				$ 158
Book value and sales cost				$ 158

[1] The properties included in this portfolio disposition are: 610 Business Center, 7800 West Brown Deer Road, Ameritrade, Barry Pointe Office Park, Benton Business Park, Brenwood, Brook Valley I, Crosstown Centre, Golden Hills Office Center, Granite Corporate Center, Great Plains, Highlands Ranch I, Highlands Ranch II, Interlachen Corporate Center, Intertech Building, Minnesota National Bank, Northpark Corporate Center, Omaha 10802 Farnam Dr, Plaza VII, Plymouth 5095 Nathan Lane, Prairie Oak Business Center, Rapid City 900 Concourse Drive, Spring Valley IV, Spring Valley V, Spring Valley X, Spring Valley XI, Superior Office Building, TCA Building & vacant land, Three Paramount Plaza, UHC Office, US Bank Financial Center, Wells Fargo Center, West River Business Park and Westgate.

[2] The properties included in this portfolio disposition are: Mendota Office Center I, Mendota Office Center II, Mendota Office Center III, Mendota Office Center IV and American Corporate Center.

[3] The properties included in this portfolio disposition are: Champlin South Pond, Chan West Village, Duluth 4615 Grand, Duluth Denfeld Retail, Forest Lake Auto, Forest Lake Westlake Center, Grand Forks Medpark Mall, Jamestown Buffalo Mall, Jamestown Business Center, Lakeville Strip Center, Monticello C Store & vacant land, Omaha Barnes & Noble, Pine City Evergreen Square, Rochester Maplewood Square and St. Cloud Westgate.

[4] On January 29, 2016, we transferred ownership of nine properties to the mortgage lender on a $122.6 million non-recourse loan and removed the debt obligation and accrued interest from our balance sheet. The properties had an estimated fair value of $89.3 million on the transfer date. Upon completion of this transfer, we recognized a gain on extinguishment of debt of $36.5 million, representing the difference between the loan and accrued interest payable extinguished over the carrying value of the properties, cash, accounts payable and accounts receivable transferred as of the transfer date and related closing costs.

[5] The properties included in this portfolio disposition are: Corporate Center West, Farnam Executive Center, Flagship Corporate Center, Gateway Corporate Center, Miracle Hills One, Pacific Hills, Riverport, Timberlands, and Woodlands Plaza IV.