Product Warranty (Schedule Of Warranty Liability) (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Product Warranties Disclosures [Abstract]
Warranty claims period	2 months
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Beginning balance	$ 3,262	$ 2,926
Accrual	10,076	9,314
Settlements	(9,791)	(9,060)
Ending balance	$ 3,547	$ 3,180