Product Warranty (Schedule Of Warranty Liability) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Product Warranty [Abstract]
Beginning balance at May 1	$ 1,795	$ 1,885
Accrual	2,546	2,257
Settlements	(2,596)	(2,160)
Ending balance at January 31	$ 1,745	$ 1,982