SHAREHOLDERS’ EQUITY (Details) - USD ($)				3 Months Ended	12 Months Ended
	Dec. 07, 2016	Dec. 02, 2016	Aug. 07, 2012	Oct. 31, 2013	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Conversion of Units to Common Shares. [Abstract]
Units converted to common stock (in shares)					503,000	273,000
Units converted to common stock					$ 875,000	$ 1,500,000
Share Repurchase Program [Member]
Share Repurchase Program
Authorized share repurchase amount	$ 50,000,000
Repurchase period	1 year
Stock Repurchased and Retired During Period, Shares					778,000	4,600,000
Stock Repurchased and Retired During Period, Value					$ 4,500,000	$ 35,000,000
Share price (in dollars per share)					$ 5.77	$ 7.52
2015 Incentive Plan [Member]
Equity Awards
Forfeited (in shares)					274,000
2015 Incentive Plan [Member] | Performance Shares [Member]
Equity Awards
Issued (in shares)					604,000
Grant-date value					$ 2,600,000
2008 Incentive Award Plan [Member] | Performance Shares [Member]
Equity Awards
Issued (in shares)					59,000	220,000
Grant-date value					$ 352,000	$ 1,600,000
Series B Preferred Stock [Member]
Cumulative Redeemable Preferred Shares of Beneficial Interest [Abstract]
Preferred shares issued (in shares)			4,600,000		4,600,000	4,600,000
Distribution rate percentage (in hundredths)			7.95%
Sale of stock, price per share (in dollars per share)			$ 25.00
Proceeds from issuance of cumulative redeemable preferred shares			$ 111,200,000
Preferred shares liquidation (in dollars per share)			$ 25.00
Preferred shares liquidation per annum (in dollars per share)			$ 1.9875
Preferred shares liquidation preference			$ 115,000,000		$ 115,000,000	$ 115,000,000
Series A Preferred Stock [Member]
Cumulative Redeemable Preferred Shares of Beneficial Interest [Abstract]
Preferred shares issued (in shares)					0	1,150,000
Distribution rate percentage (in hundredths)		8.25%
Preferred shares liquidation preference					$ 28,750,000	$ 28,750,000
Aggregate redemption price		$ 29,200,000
Common Shares and Limited Partnership Units [Member]
Distribution Reinvestment and Share Purchase Plan [Abstract]
Aggregate offering price				$ 75,000,000
Distribution Reinvestment and Share Purchase Plan [Member]
Distribution Reinvestment and Share Purchase Plan [Abstract]
Shares issued (in shares)					0	821,000	8,100,000
Shares issued						$ 5,600,000	$ 64,900,000
Distribution Reinvestment and Share Purchase Plan [Member] | Voluntary cash contributions [Member]
Distribution Reinvestment and Share Purchase Plan [Abstract]
Shares issued (in shares)						211,000
Shares issued						$ 1,500,000
Distribution Reinvestment and Share Purchase Plan [Member] | Reinvested distributions [Member]
Distribution Reinvestment and Share Purchase Plan [Abstract]
Shares issued (in shares)						610,000
Shares issued						$ 4,100,000