PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Unrecognized Benefit Amounts) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 24, 2017	Sep. 25, 2016
Pension Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net actuarial loss (gain), beginning of period	$ 46,494	$ 38,115
Amortization	(699)	(494)
Curtailment and settlement adjustments	0	0
Actuarial loss (gain)	9,433	12,233
Asset loss (gain)	(5,381)	(828)
Net actuarial loss (gain), end of period	49,847	49,026
Other Benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net actuarial loss (gain), beginning of period	(31)	(79)
Amortization	0	0
Curtailment and settlement adjustments	0	0
Actuarial loss (gain)	25	95
Asset loss (gain)	0	0
Net actuarial loss (gain), end of period	$ (6)	$ 16