STOCKHOLDERS' EQUITY (AOCI comp) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Changes in accumulated other comprehensive loss, net of tax, by component
Balances	$ 599,055
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	610	$ (2,231)
Balances	591,676
Accumulated Other Comprehensive Loss
Changes in accumulated other comprehensive loss, net of tax, by component
Balances	(23,417)	(27,496)
Other comprehensive income (loss) before reclassifications	(1,217)	(3,466)
Amounts reclassified from accumulated other comprehensive loss	1,827	1,235
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	610	(2,231)
Balances	(22,807)	(29,727)
Unrecognized Net Periodic Benefit Costs
Changes in accumulated other comprehensive loss, net of tax, by component
Balances	(21,886)	(25,497)
Other comprehensive income (loss) before reclassifications	(1,471)	(3,504)
Amounts reclassified from accumulated other comprehensive loss	1,827	1,235
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	356	(2,269)
Balances	(21,530)	(27,766)
Interest Rate Swap
Changes in accumulated other comprehensive loss, net of tax, by component
Balances	(329)	(545)
Other comprehensive income (loss) before reclassifications	135	(546)
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	135	(546)
Balances	(194)	(1,091)
Foreign Currency Translation
Changes in accumulated other comprehensive loss, net of tax, by component
Balances	(1,202)	(1,454)
Other comprehensive income (loss) before reclassifications	119	584
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	119	584
Balances	$ (1,083)	$ (870)