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Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Long-Term Investments) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 26, 2018 | Dec. 27, 2017 | Dec. 28, 2016
Investment [Line Items] |  |  |
Net gain (loss) on investments | $ 9 | $ 0 | $ 0
Non-qualified deferred compensation plan [Member] |  |  |
Investment [Line Items] |  |  |
Net gain (loss) on investments | $ (1,000) | $ 1,600 | $ 900

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- Definition Amount of realized and unrealized gain (loss) on investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27405-111563 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7(c),9(a)) -URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227 Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585 + Details
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