Income Taxes (Schedule Of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
Income Tax Disclosure [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
Research and experimentation tax credit	(0.00%)	(2.30%)	(0.00%)
Meals and entertainment	0.30%	0.50%	0.80%
Domestic production deduction	(2.50%)	(2.40%)	(1.80%)
Other	(0.10%)	0.10%	0.70%
Total	(2.30%)	(4.10%)	(0.30%)
Effective federal income tax rate	32.70%	30.90%	34.70%
State income taxes, net of federal tax effect	3.30%	3.80%	4.50%
Effective income tax rate	36.00%	34.70%	39.20%
Income taxes paid	$ 24.5	$ 13.3	$ 4.3