REDEEMABLE NONCONTROLLING INTERESTS (Details) $ in Thousands	12 Months Ended
	Apr. 30, 2017 USD ($) item	Apr. 30, 2016 USD ($)	Apr. 30, 2015 USD ($)
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of fiscal year	$ 7,522
Contributions	7,188		$ 8,909
Balance at close of fiscal year	$ 7,181	$ 7,522
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	$ 7,522	6,368	6,203
Contributions	81	1,120
Net income	(422)	34	165
Balance at close of fiscal year	$ 7,181	$ 7,522	$ 6,368