DISCONTINUED OPERATIONS - Effect on Net Income from Properties Classified as Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
REVENUE	$ 45,638	$ 41,866	$ 91,584	$ 82,844
EXPENSES
Property operating expenses, excluding real estate taxes	14,247	14,108	28,706	26,982
Depreciation and amortization	19,191	17,270	37,803	42,608
General and administrative expenses	3,374	3,118	7,244	7,120
TOTAL EXPENSES	43,445	40,593	87,048	89,557
Interest expense	(7,997)	(8,509)	(16,382)	(16,640)
Loss on extinguishment of debt	(4)	(334)	(556)	(533)
Interest income	410	199	891	220
Other income	19	56	54	263
Gain (loss) on sale of discontinued operations			9,562	17,686
INCOME (LOSS) FROM DISCONTINUED OPERATIONS	0	15,130	570	17,815
Discontinued Operations, Disposed of by Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
REVENUE	0	12,047	0	24,002
EXPENSES
Property operating expenses, excluding real estate taxes	0	2,387	0	4,644
Real estate taxes	0	1,946	0	3,907
Depreciation and amortization	0	3,424	0	7,013
General and administrative expenses	0	15	0	15
TOTAL EXPENSES	0	7,840	0	15,719
Operating income (loss)	0	4,207	0	8,283
Interest expense	0	(1,436)	0	(3,421)
Loss on extinguishment of debt	0	(6)	0	(6)
Interest income	0	117	0	661
Other income	0	10	0	60
Income (loss) from discontinued operations before gain (loss) on sale	0	2,892	0	5,577
Gain (loss) on sale of discontinued operations	0	12,238	570	12,238
INCOME (LOSS) FROM DISCONTINUED OPERATIONS	0	15,130	570	17,815
Management Service [Member]
EXPENSES
Property management expense	1,319	1,372	2,686	2,728
Management Service [Member] | Discontinued Operations, Disposed of by Sale [Member]
EXPENSES
Property management expense	$ 0	$ 68	$ 0	$ 140