Product Warranty (Schedule Of Warranty Liability) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2016	Jul. 31, 2015
Product Warranties Disclosures [Abstract]
Warranty claims period	2 months
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Beginning balance	$ 2,926	$ 2,643
Accrual	4,420	3,756
Settlements	(4,334)	(3,522)
Ending balance	$ 3,012	$ 2,877