DEFINED BENEFIT RETIREMENT PLAN (Details 2) £ in Thousands, $ in Thousands	12 Months Ended
	Dec. 28, 2019 USD ($)	Dec. 28, 2019 GBP (£)	Dec. 29, 2018 USD ($)	Dec. 30, 2017 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Limit on employer contributions per annum	$ 17,132	£ 13,100
Administrative costs of the Plan	1,700	£ 1,300
Plan assets at fair value	38,388		$ 61,546
Plan assets at NAV	566,008		441,990
Total plan assets	604,396		503,536	$ 593,749
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 38,388		61,546
Mutual funds and diversified growth funds
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage	50.00%
Temporary cash investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 38,388		61,040
Temporary cash investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	38,388		61,040
Corporate stock
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0		506
Plan assets at NAV	234,612		183,750
Corporate stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0		506
Leveraged inflation-linked gilt funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at NAV	123,637		122,711
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at NAV	97,638		80,454
Secured income asset funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at NAV	$ 110,121		$ 55,075