BENEFIT PLANS: (Details 6)	12 Months Ended
	Apr. 30, 2015	Apr. 30, 2014
Schedule Of Allocation Of Plan Assets [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	100.00%	100.00%
Equity Securities [Member]
Schedule Of Allocation Of Plan Assets [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	69.00%	65.00%
Cash Equivalents [Member]
Schedule Of Allocation Of Plan Assets [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	2.00%	8.00%
Fixed Income Securities [Member]
Schedule Of Allocation Of Plan Assets [Line Items]
Defined Benefit Plan, Target Plan Asset Allocations	29.00%	27.00%