Income Taxes (Effective Tax Rate Reconciliation) (Details)	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Reconciles our effective tax rate to the federal statutory tax rate in the United States
U.S. federal statutory rate	35.00%	35.00%	35.00%
State taxes, net of U.S. federal tax benefit	0.90%	1.00%	1.00%
Income taxed at other than U.S. federal statutory rate	(1.70%)	(2.50%)	(0.50%)
Tax benefit from U.S. manufacturing	(2.40%)	(2.40%)	(2.50%)
Tax impact of sale of business	0.00%	(1.10%)	0.00%
Amortization of deferred tax benefit from intercompany transactions	(1.70%)	(1.60%)	(1.60%)
Excess tax benefits from stock-based awards	(1.00%)	0.00%	0.00%
Other, net	(0.80%)	(0.10%)	0.30%
Effective rate	28.30%	28.30%	31.70%