COMMITMENTS AND CONTINGENCIES, Development, Expansion and Renovation Projects (Details)	3 Months Ended
	Jul. 31, 2016 USD ($) ft² item property	Jul. 31, 2015 USD ($)
Real Estate Properties [Line Items]
Anticipated Total Cost	$ 105,074,000
Project costs incurred to date	99,633,000
Construction interest capitalized	153,000	$ 2,300,000
Other [Member]
Real Estate Properties [Line Items]
Project costs incurred to date	$ 3,155,000
Multi-Family Residential [Member] | 71 France Phase I, II, III - Edina, MN [Member]
Real Estate Properties [Line Items]
Number of apartment units | item	241
Anticipated Total Cost	$ 73,290,000
Project costs incurred to date	$ 72,230,000
Interest in joint venture (in hundredths)	52.60%
Area of real estate property | ft²	21,772
Multi-Family Residential [Member] | Monticello Crossings - Monticello, MN
Real Estate Properties [Line Items]
Number of apartment units | item	202
Anticipated Total Cost	$ 31,784,000
Project costs incurred to date	$ 24,248,000
Estimated quarter for completion	3Q
Estimated year for completion	2017
Senior Housing properties [Member] | Idaho, Senior Housing and Unimproved Land [Member]
Real Estate Properties [Line Items]
Number of real estate properties classified as held for sale | property	8
Sales price of pending disposition	$ 43,500,000