BENEFIT PLANS: (Details 5)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012
Defined Benefit Plan, Target Plan Asset Allocations	100.00%	100.00%
Fixed Income Securities [Member]
Defined Benefit Plan, Target Plan Asset Allocations	21.00%	20.00%
Equity Securities [Member]
Defined Benefit Plan, Target Plan Asset Allocations	67.00%	76.00%
Cash Equivalents [Member]
Defined Benefit Plan, Target Plan Asset Allocations	5.00%	4.00%