PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Unrecognized Benefit Amounts) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 24, 2017
Pension Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net actuarial loss (gain), beginning of period	$ 54,235	$ 46,494
Amortization	(902)	(699)
Actuarial loss (gain)	(9,787)	9,433
Asset loss (gain)	2,695	(5,381)
Net actuarial loss (gain), end of period	46,241	49,847
Other Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net actuarial loss (gain), beginning of period	35	(31)
Amortization	0	0
Actuarial loss (gain)	(67)	25
Asset loss (gain)	0	0
Net actuarial loss (gain), end of period	$ (32)	$ (6)