Product Warranty (Schedule Of Warranty Liability) (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2016	Jan. 31, 2015
Product Warranties Disclosures [Abstract]
Warranty claims period	2 months
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
Beginning balance	$ 2,643	$ 1,910
Accrual	11,668	10,818
Settlements	(11,755)	(10,380)
Ending balance	$ 2,556	$ 2,348