REDEEMABLE NONCONTROLLING INTERESTS (Details) $ in Thousands	3 Months Ended
	Jul. 31, 2017 USD ($) item	Jul. 31, 2016 USD ($)
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of fiscal year	$ 7,181
Contributions		$ 572
Balance at close of fiscal year	$ 7,010
Southgate - Minot, ND [Member]
Redeemable Noncontrolling Interest [Line Items]
Number of Joint Ventures with Buy Sell Options | item	1
Commitment Period for Joint Venture Acquisition	4 years
Balance at beginning of fiscal year	$ 7,181
Net income	(171)
Balance at close of fiscal year	$ 7,010