DEFINED BENEFIT RETIREMENT PLAN (Details) £ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) item $ / £	Dec. 31, 2016 GBP (£) item	Dec. 26, 2015 USD ($) $ / £	Dec. 27, 2014 USD ($)
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Pension retirement benefits to qualified employees as percent of final salary per year of service	1.67%	1.67%
Eligibility age	65 years	65 years
Active members of defined benefit retirement income plan | item	0	0
Foreign currency exchange rate used to translate the net pension liability | $ / £	1.2340		1.4920
Defined benefit pension liability	$ 209,470		$ 179,323
Change in Projected Benefit Obligation
Beginning balance	697,449		692,283
Interest cost	23,496		24,614
Benefits paid	(17,792)		(18,346)
Actuarial loss	(125,765)		(28,130)
Currency translation	(132,781)		(29,232)
Ending balance	696,137		697,449
Plan Assets
Fair value beginning balance	518,126
Employer contributions	1,426		16,500
Actual return on plan assets	80,538		(306)
Settlements			(18,346)
Benefits paid	(17,792)		(18,346)
Currency translation	(95,631)		(21,881)
Fair value ending balance	486,667		518,126
Funded status
Funded status	(209,470)		(179,323)	$ (150,124)
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	(106,959)		(55,953)
Actuarial loss	(66,957)		(53,661)
Currency translation gain (loss)	17,038		2,655
Balance at the end of the period	$ (156,878)		(106,959)
The estimated amount to be amortized from accumulated other comprehensive income into net periodic benefit cost in 2015			$ 2,840
Weighted average actuarial assumptions used to determine the benefit obligation
Discount rate (as a percent)	2.80%		3.75%
CPI index (as a percent)	2.25%		2.15%
RPI Inflation (as a percent)	3.15%		3.25%
Net periodic benefit expense:
Interest cost	$ 23,496		$ 24,614
Expected return on plan assets	(22,986)		(25,224)
Net periodic benefit expense	$ 1,870		$ (610)
Weighted average actuarial assumptions used to determine expense
Discount rate (as a percent)	3.75%	3.75%	3.65%
Expected return on plan assets (as a percent)	5.15%	5.15%	5.00%
RPI index (as a percent)	2.15%	2.15%	2.10%
CPI index (as a percent)	3.35%	3.35%	3.20%
Limit on employer contributions per annum	$ 12,340	£ 10,000
Administrative costs of the Plan	1,357	£ 1,100
Expected pension benefit payments
2016	16,650
2017	17,200
2018	17,800
2019	18,250
2020	18,900
2021-2025	$ 104,000
Weighted average maturity period of corporate bond portfolio	13 years	13 years