DEFINED BENEFIT RETIREMENT PLAN (Details) £ in Thousands, $ in Thousands	12 Months Ended
	Dec. 28, 2019 USD ($) item $ / £	Dec. 28, 2019 GBP (£) item	Dec. 29, 2018 USD ($) $ / £	Dec. 30, 2017 USD ($)
Defined Benefit Plan [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 | $ / £	1.308		1.269
Net periodic benefit cost	$ 3,008
Projected Benefit Obligation
Beginning balance	647,440		$ 783,301
Interest cost	16,923		17,878
Prior service costs - GMP equalization		£ 9,500	12,056
Benefits paid	(20,769)		(28,207)
Actuarial (gain) loss	79,485		(95,480)
Currency translation	21,324		(42,108)
Ending balance	744,403		647,440
Plan Assets
Fair value beginning balance	503,536		593,749
Employer contributions	18,461		1,537
Actual return on plan assets	86,081		(32,120)
Benefits paid	(20,769)		(28,207)
Currency translation	17,087		(31,423)
Fair value ending balance	604,396		503,536
Funded status
Funded status	(140,007)		(143,904)	$ (189,552)
Accumulated other comprehensive income (loss)
Balance at the beginning of the period	(130,188)		(168,250)
Actuarial gain (loss)	(10,839)		44,760
Prior service costs - GMP equalization			(12,056)
Currency translation gain (loss)	(2,699)		5,358
Balance at the end of the period	$ (143,726)		$ (130,188)
Weighted average actuarial assumptions used to determine the benefit obligation
Discount rate	2.05%		2.90%
CPI inflation	2.15%		2.20%
RPI inflation	3.05%		3.30%
Net Periodic Benefit Cost:
Interest cost	$ 16,923		$ 17,878
Expected return on plan assets	(20,000)		(23,175)
Amortization of prior service cost	513		0
Amortization of actuarial loss	2,051		3,046
Net periodic benefit expense (benefit)	$ (513)		$ (2,251)
Weighted average actuarial assumptions used to determine expense
Discount rate	2.90%	2.90%	2.55%
Expected return on plan assets	4.25%	4.25%	4.29%
CPI Inflation	2.20%	2.20%	2.20%
RPI Inflation	3.30%	3.30%	3.30%
Limit on employer contributions per annum	$ 17,132	£ 13,100
Administrative costs of the Plan	1,700	£ 1,300
Expected pension benefit payments
2020	21,840
2021	22,494
2022	23,148
2023	23,802
2024	24,587
Years 2024 - 2029	$ 134,442
Weighted average maturity period of corporate bond portfolio	13 years	13 years