EMPLOYEE BENEFITS (Details)		1 Months Ended	3 Months Ended			9 Months Ended
	Mar. 22, 2019	Feb. 28, 2019 USD ($) employee	Sep. 29, 2019 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 29, 2019 USD ($) item	Sep. 30, 2018 USD ($)	Dec. 30, 2018 USD ($)
EMPLOYEE BENEFITS
Matching contributions			$ 500,000		$ 600,000	$ 1,600,000	$ 1,900,000
Pension plan
EMPLOYEE BENEFITS
Number of new participants | item						0
Further benefits			$ 0			$ 0
Special termination benefits						$ 6,834,000
ERIP
EMPLOYEE BENEFITS
Number of employee offered with voluntary early retirement incentive Program | employee		450
Percentage of employees opted for voluntary early retirement incentive Program		50.00%
Lump sum pension and termination payments		$ 35,100,000
Discount rate (as a percent)	4.10%
Expected long-term return on plan assets (as a percent)	7.75%
Remeasurement resulted in a net reduction to the pension liability				$ 13,100,000
Unfunded liability for the pension plan				$ 535,100,000				$ 548,200,000