PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Defined Benefit Plan Obligations and Assets) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012	Dec. 25, 2011
Change in plan assets:
Fair value of plan assets, end of year	$ 113,552	$ 108,496
Pension Benefits [Member]
Change in projected benefit obligation:
Projected benefit obligation, beginning of year	170,030	194,434
Interest cost	8,103	7,954	8,272
Actuarial losses (gains)	24,670	(24,315)
Benefits paid	(12,154)	(8,043)
Curtailments and settlements	(248)	0
Projected benefit obligation, end of year	190,401	170,030	194,434
Change in plan assets:
Fair value of plan assets, beginning of year	108,496	92,283
Actual return on plan assets	3,944	16,489
Contributions by employer	13,514	7,767
Benefits paid	(12,154)	(8,043)
Curtailments and settlements	(248)	0
Fair value of plan assets, end of year	113,552	108,496	92,283
Funded status:
Unfunded benefit obligation, end of year	(76,849)	(61,534)
Amounts recognized in the Consolidated Balance Sheets at end of year:
Current liability	(9,373)	(9,146)
Long-term liability	(67,476)	(52,388)
Recognized liability	(76,849)	(61,534)
Amounts recognized in accumulated other comprehensive loss at end of year:
Net actuarial loss (gain)	43,907	16,957	53,368	31,108
Other Benefits [Member]
Change in projected benefit obligation:
Projected benefit obligation, beginning of year	1,705	1,933
Interest cost	81	78
Actuarial losses (gains)	(10)	(92)
Benefits paid	0	0
Curtailments and settlements	(119)	(214)
Projected benefit obligation, end of year	1,657	1,705
Change in plan assets:
Fair value of plan assets, beginning of year	0	0
Actual return on plan assets	0	0
Contributions by employer	119	214
Benefits paid	0	0
Curtailments and settlements	(119)	(214)
Fair value of plan assets, end of year	0	0
Funded status:
Unfunded benefit obligation, end of year	(1,657)	(1,705)
Amounts recognized in the Consolidated Balance Sheets at end of year:
Current liability	(129)	(148)
Long-term liability	(1,528)	(1,557)
Recognized liability	(1,657)	(1,705)
Amounts recognized in accumulated other comprehensive loss at end of year:
Net actuarial loss (gain)	$ (127)	$ (126)	$ (49)	$ (217)