Long-Term Debt and Lines of Credit - Long-Term Debt Narrative (Detail) (USD $)	12 Months Ended					12 Months Ended
	Apr. 28, 2013	Apr. 29, 2012	May 01, 2011	Apr. 28, 2013 Unsecured senior term notes [Member]	Aug. 11, 2008 Unsecured senior term notes [Member]	Apr. 28, 2013 Government of Quebec Term Loan [Member]
Debt Instrument [Line Items]
Issuance of unsecured term notes					$ 11,000,000
Fixed interest rate					8.01%
Term of the note agreement				7 years
Required amount of principal payment installments				2,200,000
Date of first required principal payment				Aug. 11, 2011
Required debt payment frequency				Annual
Average term period for remaining principal payments, in years				2 years 3 months 18 days
Maturity date				Aug. 11, 2015		Dec. 01, 2013
Principal payment requirements of long-term debt for the first year	2,200,000
Principal payment requirements of long-term debt for the second year	2,200,000
Principal payment requirements of long-term debt for the third year	2,200,000
Interest paid	$ 666,000	$ 817,000	$ 901,000