Income Taxes (Effective Tax Rate Reconciliation) (Details)	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Reconciles our effective tax rate to the federal statutory tax rate in the United States
U.S. federal statutory rate	21.00%	30.40%	35.00%
State taxes, net of U.S. federal tax benefit	2.10%	0.80%	0.90%
Income taxed at other than U.S. federal statutory rate	(0.10%)	(3.40%)	(1.70%)
Tax benefit from foreign-derived sales	(1.70%)	(0.00%)	(0.00%)
Adjustments related to prior years	(1.20%)	(0.90%)	(0.70%)
Tax benefit from U.S. manufacturing	(0.00%)	(2.50%)	(2.40%)
Amortization of deferred tax benefit from intercompany transactions	0.00%	(1.60%)	(1.70%)
Excess tax benefits from stock-based awards	(0.70%)	(1.80%)	(1.00%)
Impact of Tax Act	(0.40%)	2.50%	0.00%
Other, net	0.80%	3.10%	(0.10%)
Effective rate	19.80%	26.60%	28.30%