BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Details) (USD $)	3 Months Ended
	Jul. 31, 2014 Redemption Property	Jul. 31, 2013	Apr. 30, 2014
BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Interest in operating partnership (in hundredths)	86.50%		83.80%
Redemption basis	one-for-one
Redemptions by limited partner, maximum	2
Number of units to redeem, minimum (in units)	1,000
Period to hold the beneficial interest, minimum	1 year
Real Estate Properties [Line Items]
Impairment of retail property	$ 2,320,000	$ 1,803,000
Impairment of retail property attributable to discontinued operations	0
Number of impaired properties	2
Compensating Balances [Line Items]
Compensating balances	10,000,000
Remaining terms of certificates of deposit	6 months	2 years
Decrease in lender holdbacks	609,000	1,144,000
Increase in lender holdbacks	326,000	279,000
Dacotah Bank, Minot, North Dakota [Member]
Compensating Balances [Line Items]
Compensating balances	350,000
Commerce Bank [Member]
Compensating Balances [Line Items]
Compensating balances	100,000
United Community Bank, Minot, North Dakota [Member]
Compensating Balances [Line Items]
Compensating balances	275,000
First International Bank, Watford City, North Dakota [Member]
Compensating Balances [Line Items]
Compensating balances	6,100,000
Peoples State Bank of Velva, North Dakota [Member]
Compensating Balances [Line Items]
Compensating balances	225,000
Associated Bank, Green Bay, Wisconsin [Member]
Compensating Balances [Line Items]
Compensating balances	600,000
American National Bank, Omaha, Nebraska [Member]
Compensating Balances [Line Items]
Compensating balances	400,000
Private Bank [Member]
Compensating Balances [Line Items]
Compensating balances	2,000,000
United Community and Dacotah Bank [Member] | Other Investments [Member]
Compensating Balances [Line Items]
Certificates of deposit	329,000
Anoka, Minnesota [Member]
Real Estate Properties [Line Items]
Impairment of retail property	265,000
Number of impaired properties	1
Kalispell, Montana, retail property [Member]
Real Estate Properties [Line Items]
Impairment of retail property	2,100,000
Number of impaired properties	1
Golden Valley, Minnesota, office property [Member]
Real Estate Properties [Line Items]
Impairment of retail property	183,000
Number of impaired properties	1
Bloomington, Minnesota [Member]
Real Estate Properties [Line Items]
Impairment of retail property	329,000
Number of impaired properties	1
Clive, Iowa [Member]
Real Estate Properties [Line Items]
Impairment of retail property	345,000
Number of impaired properties	1
St. Louis Park, Minnesota [Member]
Real Estate Properties [Line Items]
Impairment of retail property	$ 864,000
Number of impaired properties	1