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. 30, 2018	Sep. 24, 2017	Sep. 30, 2018	Sep. 24, 2017
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	$ 1,366	$ 1,392	$ 4,097	$ 4,178
Estimated return on plan assets	(1,516)	(1,314)	(4,549)	(3,940)
Amortization of net loss	300	233	902	699
Net costs	150	311	450	937
Other Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Interest cost	12	13	35	38
Estimated return on plan assets	0	0	0	0
Amortization of net loss	0	0	0	0
Net costs	$ 12	$ 13	$ 35	$ 38