EQUITY (Details) - USD ($)	3 Months Ended				6 Months Ended
	Oct. 31, 2015	Jul. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Aggregate offering price					$ 75,000,000
Aggregate cost of common shares repurchased					$ 21,931,000
Units converted to common shares (in shares)	75,500		3,300,000		154,000	6,400,000
Units converted to common shares	$ 279,000		$ 19,400,000		$ 855,000	$ 37,700,000
Share Repurchase Program [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Aggregate gross sales price of common share of beneficial interest allowed to be repurchased	$ 50,000,000				$ 50,000,000
Common shares repurchased (in shares)					2,900,000
Aggregate cost of common shares repurchased					$ 21,900,000
Average price of shares issued (in dollars per share)					$ 7.69
2008 Incentive Award Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Shares issued (in shares)		220,000		204,000
Shares issued		$ 1,600,000		$ 1,900,000
Restricted shares (in shares)		108,000
Distribution Reinvestment and Share Purchase Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Shares issued (in shares)	55,000		1,800,000		821,000	4,200,000
Shares issued	$ 377,000		$ 13,900,000		$ 5,600,000	$ 34,800,000
Shares registered (in shares)					10,000
Average price of shares issued (in dollars per share)	$ 6.87		$ 7.76		$ 6.85	$ 8.27
Distribution Reinvestment Waiver [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Shares issued (in shares)						926,000
Shares issued						$ 8,000,000
Average price of shares issued (in dollars per share)						$ 8.64