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Note 7 - Fair Value of Assets and Liabilities - Assets Measured at Fair Value (Details) - Polytronics [Member] - USD ($) $ in Thousands | Dec. 30, 2017 | Dec. 31, 2016
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Investment in Polytronics | $ 10,993 | $ 10,435
Fair Value, Inputs, Level 1 [Member] |  |
Investment in Polytronics | 10,993 | 10,435
Fair Value, Inputs, Level 2 [Member] |  |
Investment in Polytronics |  |
Fair Value, Inputs, Level 3 [Member] |  |
Investment in Polytronics |  |

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562 + Details
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