BENEFIT PLANS: - Allocation for the pension plan by asset category (Details)	Apr. 30, 2020	Apr. 30, 2019
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%	100.00%
Equity Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	27.00%	52.00%
Fixed Income Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	59.00%	45.00%
Cash Equivalents [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	14.00%	3.00%