Long-Term Debt and Lines of Credit (Detail) (USD $) In Thousands, unless otherwise specified	Oct. 27, 2013	Apr. 28, 2013		Oct. 28, 2012
Debt Instrument [Line Items]
Long-term Debt	$ 4,400	$ 6,600		$ 6,817
Current maturities of long-term debt	(2,200)	(2,200)	[1]	(2,401)
Long-term debt, less current maturities of long-term debt	2,200	4,400	[1]	4,416
Unsecured senior term notes [Member]
Debt Instrument [Line Items]
Long-term Debt	4,400	6,600		6,600
Canadian government loan [Member]
Debt Instrument [Line Items]
Long-term Debt				$ 217

[1] Derived from audited financial statements.