PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Net Defined Benefit Pension and Other Postretirement Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2021	Sep. 27, 2020	Sep. 26, 2021	Sep. 27, 2020
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	$ 1,682	$ 1,997	$ 4,119	$ 6,047
Estimated return on plan assets	(3,170)	(3,256)	(7,626)	(9,754)
Settlement loss	539	2,941	1,376	2,941
Expenses paid from plan assets	110	87	279	624
Amortization of net loss	607	376	1,553	1,127
Amortization of past service cost	6	0	14	0
Net costs	(226)	2,145	(285)	985
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	4	9	12	27
Estimated return on plan assets	0	0	0	0
Settlement loss	0	0	0	0
Expenses paid from plan assets	0	0	0	0
Amortization of net loss	0	0	1	0
Amortization of past service cost	0	0	0	0
Net costs	$ 4	$ 9	$ 13	$ 27