PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Unrecognized Benefit Amounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 25, 2016	Dec. 27, 2015	Dec. 28, 2014
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Actuarial loss (gain)	$ 5,247	$ (3,575)	$ 16,775
Pension Benefits [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Net actuarial loss (gain), beginning of year	38,115	43,907	16,957
Amortization	(659)	(714)	(56)
Settlement adjustments	(2,064)	(3,843)	(93)
Actuarial loss (gain)	10,305	(10,944)	24,670
Asset loss (gain)	797	9,709	2,429
Net actuarial loss (gain), end of year	46,494	38,115	43,907
Other Benefits [Member]
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Net actuarial loss (gain), beginning of year	(79)	(127)	(126)
Amortization	0	0	0
Settlement adjustments	2	4	9
Actuarial loss (gain)	46	44	(10)
Asset loss (gain)	0	0	0
Net actuarial loss (gain), end of year	$ (31)	$ (79)	$ (127)