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DEFINED BENEFIT RETIREMENT PLAN (Details 2) - USD ($) $ in Thousands | Dec. 31, 2016 | Dec. 26, 2015 | Dec. 27, 2014
--- | --- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | $ 2,380 | $ 5,181 | $ 542,159
Plan assets at NAV | 484,287 | 512,945 |
Total plan assets | 486,667 | 518,126 |
Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 2,380 | 5,181 |
Temporary cash investments |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 1,900 | 4,673 |
Temporary cash investments | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 1,900 | 4,673 |
Index linked gilts |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at NAV | 135,141 | 123,257 |
Corporate bonds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at NAV | 83,834 | 100,701 |
Corporate stock |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 480 | 508 |
Plan assets at NAV | 165,338 | 172,456 |
Corporate stock | Fair Value, Inputs, Level 1 [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at fair value | 480 | 508 |
Diversified growth funds |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Plan assets at NAV | $ 99,974 | $ 116,531 |

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- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 30 -Section 35 -Paragraph 50 -URI http://asc.fasb.org/extlink&oid=64937038&loc=d3e12355-114930 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Plan Assets -URI http://asc.fasb.org/extlink&oid=6749337 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Plan Assets -URI http://asc.fasb.org/extlink&oid=6520858 + Details
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