Income Taxes (Effective Tax Rate Reconciliation) (Details)	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
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	1.00%	1.00%	0.70%
Income taxed at other than U.S. federal statutory rate	(2.50%)	(0.50%)	(2.20%)
Tax benefit from U.S. manufacturing	(2.40%)	(2.50%)	(2.80%)
Effective Income Tax Rate Reconciliation, Disposition of Business, Percent	(1.10%)	0.00%	0.00%
Amortization of deferred tax benefit from intercompany transactions	(1.60%)	(1.60%)	(0.40%)
Other, net	(0.10%)	0.30%	0.20%
Effective rate	28.30%	31.70%	30.50%