Note 2 - Certain Significant Estimates - Allowance for Doubtful Accounts (Details) - SEC Schedule, 12-09, Allowance, Credit Loss [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 25, 2021	Dec. 26, 2020	Dec. 28, 2019
Beginning balance	$ 896	$ 483	$ 532
Additions	(408)	473	322
Deductions	(31)	(60)	(371)
Ending balance	$ 457	$ 896	$ 483

Amount of valuation and qualifying accounts and reserves.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09(Column B))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09(Column E))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690

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- Definition

Amount of decrease in valuation and qualifying accounts and reserves.

+ References

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- Definition

Amount of increase (decrease) in valuation and qualifying accounts and reserves.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e24092-122690

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