COMMITMENTS AND CONTINGENCIES: (Details Textual) (USD $)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Operating Leases, Rent Expense	$ 3,022,000	$ 3,035,000	$ 3,334,000
Capital Leases, Future Minimum Payments Due	3,130,000
Operating Leases, Future Minimum Payments Due, Next Twelve Months	1,571,000
Operating Leases, Future Minimum Payments, Due in Two Years	840,000
Operating Leases, Future Minimum Payments, Due in Three Years	696,000
Operating Leases, Future Minimum Payments, Due in Four Years	23,000
Operating Leases, Future Minimum Payments, Due in Five Years	0
Operating Leases, Future Minimum Payments, Due Thereafter	0
Future Development Commitments	$ 3,100,000