Note 10 - Pension Plans (Details) - Contribution for Multi-Employer Pension Plans (USD $) In Thousands, unless otherwise specified	12 Months Ended
Apr. 27, 2013	Apr. 28, 2012	Apr. 30, 2011
Multiemployer Plans [Line Items]
Contribution	$ 1,784	$ 1,643	$ 1,733
CSSS Fund [Member]
Multiemployer Plans [Line Items]
Contribution	1,051	944	897
WCT Fund [Member]
Multiemployer Plans [Line Items]
Contribution	471	455	612
Other Multi-Employer Pension Funds [Member]
Multiemployer Plans [Line Items]
Contribution	$ 262	$ 244	$ 224

Amount of contributions made to multiemployer plans by the employer. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=14450570&loc=SL14450702-114947

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=14450570&loc=SL14450691-114947

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 80

-Section 50

-Paragraph 5

-Subparagraph (e)(1)

-URI http://asc.fasb.org/extlink&oid=14450570&loc=SL14450657-114947

Name:	us-gaap_MultiemployerPlanPeriodContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration