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