BENEFIT PLANS: (Details 1)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Discount rate used to determine net periodic pension cost	3.97%	5.05%	5.44%
Discount rate used to determine pension benefit obligation	3.47%	3.97%	5.05%
Expected long-term rate of return on assets on assets	8.00%	8.00%	8.00%