STOCKHOLDERS' EQUITY (Schedule of Changes in Unrealized Actuarial Losses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 30, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	$ (45,735)
Other comprehensive income (loss) before reclassifications	(5,806)
Amounts reclassified from accumulated other comprehensive loss to net income	(16)
Net current period other comprehensive income (loss)	(5,822)	10,410
Balance, end of period	(51,557)
Losses Related to Pension and Other Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	(45,797)	(68,511)
Other comprehensive income (loss) before reclassifications	(5,795)	10,160
Amounts reclassified from accumulated other comprehensive loss to net income	9	250
Net current period other comprehensive income (loss)	(5,786)	10,410
Balance, end of period	(51,583)	(58,101)
Unrealized Holding Gains on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	62
Other comprehensive income (loss) before reclassifications	(11)
Amounts reclassified from accumulated other comprehensive loss to net income	(25)
Net current period other comprehensive income (loss)	(36)
Balance, end of period	$ 26