ACQUISITIONS, DEVELOPMENTS PLACED IN SERVICE AND DISPOSITIONS, PROPERTY DISPOSITIONS (Details) $ in Thousands	3 Months Ended
	Jul. 31, 2015 USD ($) ft²	Jul. 31, 2014 USD ($) ft²
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price	$ 7,000	$ 6,700
Book value and sales cost	7,175	9,693
Gain/(loss)	$ (175)	(2,993)
Other Disposition [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sales price		3,100
Book value and sales cost		4,300
Gain/(loss)		$ (1,200)
Other Disposition [Member] | 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
Other Disposition [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
Sales price		$ 3,100
Book value and sales cost		3,124
Gain/(loss)		$ (24)
Area of real estate property | ft²		73,338
Other Disposition [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)
Area of real estate property | ft²		25,644
Commercial Industrial [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
Sales price		$ 3,600
Book value and sales cost		5,393
Gain/(loss)		$ (1,793)
Area of real estate property | ft²		198,600