Product Warranty (Schedule Of Warranty Liability) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Product Warranty [Abstract]
Beginning balance at May 1	$ 1,795	$ 1,885
Accrual	5,950	4,953
Settlements	(5,820)	(4,747)
Ending balance at October 31	$ 1,925	$ 2,091