PENSION AND OTHER POSTRETIREMENT BENEFITS - Schedule of Defined Benefit Plan Obligations and Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2019	Jul. 01, 2018	Dec. 30, 2018	Dec. 31, 2017
Change in plan assets:
Fair value of plan assets, beginning of period			$ 102,414
Fair value of plan assets, end of period	$ 110,104		110,104
Pension Benefits
Change in projected benefit obligation:
Projected benefit obligation, beginning of period			157,619	$ 178,247
Interest cost	1,467	$ 1,365	2,934	2,731
Actuarial losses (gains)			13,734	(9,465)
Benefits paid			(3,020)	(4,473)
Curtailments and settlements			(5,718)	0
Projected benefit obligation, end of period	165,549	167,040	165,549	167,040
Change in plan assets:
Fair value of plan assets, beginning of period			102,414	112,570
Actual return on plan assets			12,504	97
Contributions by employer			3,924	5,581
Benefits paid			(3,020)	(4,473)
Fair value of plan assets, end of period	110,104	113,775	110,104	113,775
Funded status:
Unfunded benefit obligation, end of period	(55,445)		(55,445)		$ (55,205)
Amounts recognized in the Condensed Consolidated Balance Sheets at end of period:
Current liability	(8,239)		(8,239)		(8,267)
Long-term liability	(47,206)		(47,206)		(46,938)
Recognized liability	(55,445)		(55,445)		(55,205)
Amounts recognized in accumulated other comprehensive loss at end of period:
Net actuarial loss (gain)	55,685	47,104	55,685	47,104	54,343	$ 54,235
Other Benefits
Change in projected benefit obligation:
Projected benefit obligation, beginning of period			1,462	1,603
Interest cost	13	11	26	23
Actuarial losses (gains)			96	(62)
Benefits paid			(74)	(74)
Curtailments and settlements			0	0
Projected benefit obligation, end of period	1,510	1,490	1,510	1,490
Change in plan assets:
Fair value of plan assets, beginning of period			0	0
Actual return on plan assets			0	0
Contributions by employer			74	74
Benefits paid			(74)	(74)
Fair value of plan assets, end of period	0	0	0	0
Funded status:
Unfunded benefit obligation, end of period	(1,510)		(1,510)		(1,462)
Amounts recognized in the Condensed Consolidated Balance Sheets at end of period:
Current liability	(148)		(148)		(149)
Long-term liability	(1,362)		(1,362)		(1,313)
Recognized liability	(1,510)		(1,510)		(1,462)
Amounts recognized in accumulated other comprehensive loss at end of period:
Net actuarial loss (gain)	$ 62	$ (27)	$ 62	$ (27)	$ (34)	$ 35