Allowance for Credit Losses (Details) (USD $)	3 Months Ended		6 Months Ended
	Oct. 27, 2012	Oct. 29, 2011	Oct. 27, 2012	Oct. 29, 2011
Allowance for Credit Losses [Abstract]
Notes receivable, gross	$ 9,000,000		$ 9,000,000
Number of customers with notes receivable balance	10		10
Notes receivable, current	1,200,000		1,200,000
Allowance for Credit Losses [Member]
Allowance for Credit Losses [Roll Forward]
Beginning balance	1,519,000	2,309,000	1,537,000	2,067,000
Recoveries	(38,000)	(18,000)	(56,000)	(18,000)
Write-offs	0	(15,000)	0	(15,000)
Provision for (reversal of) credit losses (net)	0	15,000	0	283,000
Currency effect	0	(8,000)	0	(34,000)
Ending balance	$ 1,481,000	$ 2,283,000	$ 1,481,000	$ 2,283,000