SUBSEQUENT EVENTS (Details) $ / shares in Units, $ in Thousands				3 Months Ended
	Aug. 20, 2015 USD ($) ft²	Aug. 12, 2015 USD ($) Property	Aug. 03, 2015 USD ($) Property Parcel	Jul. 31, 2015	Jul. 31, 2014 USD ($)	Sep. 02, 2015 $ / shares
Subsequent Event [Line Items]
Purchase price of acquired property					$ 26,578
Cash paid for acquisition of property					$ 12,996
Common Shares and Limited Partnership Units [Member]
Subsequent Event [Line Items]
Record date				Sep. 15, 2015
Payment date				Oct. 01, 2015
Series A Preferred Stock [Member]
Subsequent Event [Line Items]
Record date				Sep. 15, 2015
Payment date				Sep. 30, 2015
Series B Preferred Stock [Member]
Subsequent Event [Line Items]
Record date				Sep. 15, 2015
Payment date				Sep. 30, 2015
Subsequent Event [Member] | Common Shares and Limited Partnership Units [Member]
Subsequent Event [Line Items]
Quarterly amount per share or unit (in dollars per share) | $ / shares						$ 0.1300
Subsequent Event [Member] | Series A Preferred Stock [Member]
Subsequent Event [Line Items]
Quarterly amount per share or unit (in dollars per share) | $ / shares						0.5156
Subsequent Event [Member] | Series B Preferred Stock [Member]
Subsequent Event [Line Items]
Quarterly amount per share or unit (in dollars per share) | $ / shares						$ 0.4968
Subsequent Event [Member] | Healthcare [Member]
Subsequent Event [Line Items]
Number of units | Property			1
Subsequent Event [Member] | Healthcare [Member] | Omaha, Nebraska [Member]
Subsequent Event [Line Items]
Square footage acquired | ft²	28,000
Purchase price of acquired property	$ 6,500
Cash paid for acquisition of property	$ 6,500
Subsequent Event [Member] | Office Portfolio [Member]
Subsequent Event [Line Items]
Number of units | Property			33
Number of parcels of land sold | Parcel			1
Sales price of properties			$ 250,000
Gain on sale of properties			18,100
Gain (loss) on debt extinguishment			$ (4,800)
Subsequent Event [Member] | Office Portfolio [Member] | Mendota Heights, Minnesota [Member]
Subsequent Event [Line Items]
Number of units | Property		5
Sales price of properties		$ 40,000
Percentage of ownership in joint venture (in hundredths)		51.00%