PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Unrecognized Benefit Amounts) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2016	Mar. 29, 2015
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Actuarial loss	$ 6,885	$ 2,069
Pension Benefits [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net actuarial loss (gain), beginning of period	38,115	43,907
Amortization	(165)	(179)
Curtailment and settlement adjustments	0	(3,062)
Actuarial loss	4,417	6,914
Asset loss (gain)	6,759	(389)
Net actuarial loss (gain), end of period	49,126	47,191
Other Benefits [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net actuarial loss (gain), beginning of period	(79)	(127)
Amortization	0	0
Curtailment and settlement adjustments	0	0
Actuarial loss	51	39
Asset loss (gain)	0	0
Net actuarial loss (gain), end of period	$ (28)	$ (88)