BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017	May 01, 2018	Apr. 30, 2018
Disaggregation of Revenue [Line Items]
Description of timing			one year or less
Accumulated distributions in excess of net income	$ (416,819)		$ (416,819)			$ (395,669)
Rental revenue			86,394
Other property revenue			5,190
Revenues	$ 45,638	$ 41,866	$ 91,584	$ 82,844
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Disaggregation of Revenue [Line Items]
Accumulated distributions in excess of net income					$ 627
Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue			100.00%
Product Concentration Risk [Member] | Rental Revenue [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue			94.30%
Product Concentration Risk [Member] | Other Property Revenue [Member]
Disaggregation of Revenue [Line Items]
Percent of Revenue			5.70%