Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details)	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Income Tax Disclosure [Abstract]
Federal statutory rate	21.00%	21.00%	21.00%
Federal income tax credits	(1.20%)	(0.90%)	(1.40%)
Stock compensation	0.20%	(0.10%)	(0.50%)
Meals and entertainment	0.10%	0.30%	0.30%
Effect of 2017 Tax Act	0.00%	0.00%	(1.10%)
Valuation allowance for deferred taxes	0.00%	0.70%	0.60%
Foreign	0.60%	0.40%	0.80%
Other	0.20%	0.70%	1.20%
Total	(0.10%)	1.10%	(0.10%)
Effective federal income tax rate	20.90%	22.10%	20.90%
State income taxes, net of federal tax effect	3.20%	3.40%	3.60%
Effective income tax rate	24.10%	25.50%	24.50%