RETIREMENT PLANS (Details) - USD ($)	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
RETIREMENT PLANS [Abstract]
Maximum contribution each employee, towards 401(k) plan (in hundredths)	4.00%
Employer contribution towards profit sharing plan and 401(k) plan	$ 565,000	$ 836,000	$ 1,000,000
Discretionary employer contribution (as a percent)		3.50%