Note 1 - Summary of Significant Accounting Policies - Customer Concentration (Details) - Sales Revenue, Net [Member] - Customer Concentration Risk [Member]	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 24, 2017	Jun. 30, 2018	Jun. 24, 2017
Customers individually accounting for more than 10% of net sales	1	1	1	1
One Customer [Member]
Percentage of net sales	11.30%	20.70%	10.60%	20.40%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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