ACQUISITIONS, DEVELOPMENTS PLACED IN SERVICE AND DISPOSITIONS, Property Dispositions (Details)
$ in Thousands
 3 Months Ended 6 Months Ended 9 Months Ended
Jan. 29, 2016
USD ($)
Property
Jan. 31, 2016
USD ($)
ft²
Property
Jan. 31, 2015
USD ($)
ft²
Property
Unit
Jan. 31, 2016
ft²
Property
Jan. 31, 2016
USD ($)
ft²
Jan. 31, 2015
USD ($)
ft²
Unit
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]            
Sales Price   $ 3,500 $ 10,000   $ 504,914 $ 27,619
Book Value and Sales Cost         442,932 28,412
Gain/(Loss)         $ 61,982 $ (793)
Office Properties [Member]            
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]            
Number of properties sold | Property     1 48    
Number of properties transferred | Property 9          
Estimated fair value of properties transferred $ 89,300          
Retail Properties [Member]            
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]            
Number of properties sold | Property   3 1 17    
Multifamily [Member] | 83 unit - Lancaster - St. Cloud, MN [Member]            
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]            
Date Disposed           Sep. 22, 2014
Sales Price           $ 4,451
Book Value and Sales Cost           3,033
Gain/(Loss)           $ 1,418
Units | Unit     83     83
Industrial [Member] | 198,600 sq ft 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
Sales Price           $ 3,600
Book Value and Sales Cost           5,393
Gain/(Loss)           $ (1,793)
Area of real estate property | ft²     198,600     198,600
Other [Member]            
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]            
Sales Price           $ 18,898
Book Value and Sales Cost           19,316
Gain/(Loss)           $ (418)
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  
Sales Price         $ 7,000  
Book Value and Sales Cost         7,175  
Gain/(Loss)         $ (175)  
Area of real estate property | ft²   117,144   117,144 117,144  
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  
Sales Price [1]         $ 250,000  
Book Value and Sales Cost [1]         231,537  
Gain/(Loss) [1]         $ 18,463  
Area of real estate property | ft² [1]   2,549,222   2,549,222 2,549,222  
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  
Sales Price [2]         $ 40,000  
Book Value and Sales Cost [2]         41,574  
Gain/(Loss) [2]         $ (1,574)  
Area of real estate property | ft² [2]   420,216   420,216 420,216  
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  
Sales Price [3]         $ 78,960  
Book Value and Sales Cost [3]         71,913  
Gain/(Loss) [3]         $ 7,047  
Area of real estate property | ft² [3]   1,027,208   1,027,208 1,027,208  
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  
Sales Price         $ 2,900  
Book Value and Sales Cost         2,928  
Gain/(Loss)         $ (28)  
Area of real estate property | ft²   48,700   48,700 48,700  
Other [Member] | 8,526 sq ft Burnsville I 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  
Sales Price         $ 1,300  
Book Value and Sales Cost         913  
Gain/(Loss)         $ 387  
Area of real estate property | ft²   8,526   8,526 8,526  
Other [Member] | 4,800 sq ft 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  
Sales Price         $ 300  
Book Value and Sales Cost         355  
Gain/(Loss)         $ (55)  
Area of real estate property | ft²   4,800   4,800 4,800  
Other [Member] | 11,003 sq ft 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  
Sales Price         $ 1,854  
Book Value and Sales Cost         393  
Gain/(Loss)         $ 1,461  
Area of real estate property | ft²   11,003   11,003 11,003  
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  
Sales Price [4]         $ 122,600  
Book Value and Sales Cost [4]         86,144  
Gain/(Loss) [4]         $ 36,456  
Area of real estate property | ft² [4],[5]   937,518   937,518 937,518  
Other [Member] | 73,338 sq ft 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
Sales Price           $ 3,100
Book Value and Sales Cost           3,124
Gain/(Loss)           $ (24)
Area of real estate property | ft²     73,338     73,338
Other [Member] | 25,644 sq ft 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)
Area of real estate property | ft²     25,644     25,644
Other [Member] | 74,568 sq ft 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
Sales Price           $ 4,525
Book Value and Sales Cost           4,695
Gain/(Loss)           $ (170)
Area of real estate property | ft²     74,568     74,568
Other [Member] | 52,000 sq ft 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
Sales Price           $ 1,230
Book Value and Sales Cost           1,229
Gain/(Loss)           $ 1
Area of real estate property | ft²     52,000     52,000
Other [Member] | 34,226 sq ft 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
Sales Price           $ 2,843
Book Value and Sales Cost           2,211
Gain/(Loss)           $ 632
Area of real estate property | ft²     34,226     34,226
Other [Member] | 79,297 sq ft 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
Sales Price           $ 7,200
Book Value and Sales Cost           6,881
Gain/(Loss)           $ 319
Area of real estate property | ft²     79,297     79,297
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
Sales Price           $ 670
Book Value and Sales Cost           670
Gain/(Loss)           $ 0
[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, 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.