PENSION AND OTHER POSTRETIREMENT BENEFITS (Schedule of Defined Benefit Plan Obligations and Assets) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 29, 2015	Mar. 30, 2014	Dec. 28, 2014	Dec. 29, 2013
Change in plan assets:
Fair value of plan assets, beginning of year			$ 113,552
Fair value of plan assets, end of year	104,070		113,552
Funded status:
Unfunded benefit obligation, end of year	(1,680)		(1,657)
Amounts recognized in the Consolidated Balance Sheets at end of year:
Current liability	(129)		(129)
Long-term liability	(1,551)		(1,528)
Recognized liability	(1,680)		(1,657)
Pension Benefits [Member]
Change in projected benefit obligation:
Projected benefit obligation, beginning of year	190,401	170,030
Interest cost	1,938	2,026
Actuarial losses (gains)	6,915	9,017
Benefits paid	(1,479)	(3,603)
Curtailments and settlements	(11,945)	0
Projected benefit obligation, end of year	185,830	177,470
Change in plan assets:
Fair value of plan assets, beginning of year	113,552	108,496
Actual return on plan assets	2,061	1,353
Contributions by employer	1,881	1,529
Benefits paid	(1,479)	(3,603)
Curtailments and settlements	(11,945)	0
Fair value of plan assets, end of year	104,070	107,775
Funded status:
Unfunded benefit obligation, end of year	(81,760)		(76,849)
Amounts recognized in the Consolidated Balance Sheets at end of year:
Current liability	(9,368)		(9,373)
Long-term liability	(72,392)		(67,476)
Recognized liability	(81,760)		(76,849)
Amounts recognized in accumulated other comprehensive loss at end of year:
Net actuarial loss (gain)	47,191	26,201	43,907	16,957
Other Benefits [Member]
Change in projected benefit obligation:
Projected benefit obligation, beginning of year	1,657	1,705
Interest cost	17	20
Actuarial losses (gains)	38	52
Benefits paid	(32)	(37)
Curtailments and settlements	0	0
Projected benefit obligation, end of year	1,680	1,740
Change in plan assets:
Fair value of plan assets, beginning of year	0	0
Actual return on plan assets	0	0
Contributions by employer	32	37
Benefits paid	(32)	(37)
Curtailments and settlements	0	0
Fair value of plan assets, end of year	0	0
Funded status:
Unfunded benefit obligation, end of year	(1,680)		(1,657)
Amounts recognized in the Consolidated Balance Sheets at end of year:
Recognized liability	(1,680)		(1,657)
Amounts recognized in accumulated other comprehensive loss at end of year:
Net actuarial loss (gain)	$ (88)	$ (74)	$ (127)	$ (126)