STOCKHOLDERS' EQUITY (AOCI comp) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in accumulated other comprehensive loss, net of tax, by component
Balances			$ 588,728
Amounts reclassified from accumulated other comprehensive loss			3,599	$ 3,281
OTHER COMPREHENSIVE INCOME (LOSS), net of tax	$ 2,404	$ (6,635)	(943)	(4,106)
Balances	595,153		595,153
Accumulated Other Comprehensive Loss
Changes in accumulated other comprehensive loss, net of tax, by component
Balances			(27,496)	(23,479)
Other comprehensive income (loss) before reclassifications			(4,542)	(7,387)
Amounts reclassified from accumulated other comprehensive loss			3,599	3,281
OTHER COMPREHENSIVE INCOME (LOSS), net of tax			(943)	(4,106)
Balances	(28,439)	(27,585)	(28,439)	(27,585)
Unrecognized Net Periodic Benefit Costs
Changes in accumulated other comprehensive loss, net of tax, by component
Balances			(25,497)	(22,387)
Other comprehensive income (loss) before reclassifications			(4,141)	(6,232)
Amounts reclassified from accumulated other comprehensive loss			3,599	3,281
OTHER COMPREHENSIVE INCOME (LOSS), net of tax			(542)	(2,951)
Balances	(26,039)	(25,338)	(26,039)	(25,338)
Interest Rate Swap
Changes in accumulated other comprehensive loss, net of tax, by component
Balances			(545)	(350)
Other comprehensive income (loss) before reclassifications			(430)	(603)
OTHER COMPREHENSIVE INCOME (LOSS), net of tax			(430)	(603)
Balances	(975)	(953)	(975)	(953)
Foreign Currency Translation
Changes in accumulated other comprehensive loss, net of tax, by component
Balances			(1,454)	(742)
Other comprehensive income (loss) before reclassifications			29	(552)
OTHER COMPREHENSIVE INCOME (LOSS), net of tax			29	(552)
Balances	$ (1,425)	$ (1,294)	$ (1,425)	$ (1,294)