ACCUMULATED OTHER COMPREHENSIVE LOSS: (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	$ 690,809
Balance at the end of the period	698,183	$ 690,809
AOCI from Derivatives
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(1,236)	(436)
Other comprehensive earnings (loss) before reclassifications	(2,041)	(1,439)
Reclassifications from accumulated other comprehensive loss	1,602	639
Other comprehensive earnings (loss) net of tax	(439)	(800)
Balance at the end of the period	(1,675)	(1,236)
Investments
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(332)	54
Other comprehensive earnings (loss) before reclassifications	(273)	(386)
Other comprehensive earnings (loss) net of tax	(273)	(386)
Balance at the end of the period	(605)	(332)
Postretirement and Pension Benefits
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	6,439	9,367
Other comprehensive earnings (loss) before reclassifications	874	(1,776)
Reclassifications from accumulated other comprehensive loss	(926)	(1,152)
Other comprehensive earnings (loss) net of tax	(52)	(2,928)
Balance at the end of the period	6,387	6,439
Foreign Currency Translation
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(17,499)	(13,527)
Other comprehensive earnings (loss) before reclassifications	(4,145)	(3,155)
Reclassifications from accumulated other comprehensive loss		(817)
Other comprehensive earnings (loss) net of tax	(4,145)	(3,972)
Balance at the end of the period	(21,644)	(17,499)
Commodity Derivatives
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(470)	(96)
Other comprehensive earnings (loss) before reclassifications	(392)	(562)
Reclassifications from accumulated other comprehensive loss	1,035	188
Other comprehensive earnings (loss) net of tax	643	(374)
Balance at the end of the period	173	(470)
Accumulated Other Comprehensive Earnings ( Loss )
Accumulated other comprehensive earnings (loss), net of tax
Balance at the beginning of the period	(13,098)	(4,638)
Other comprehensive earnings (loss) before reclassifications	(5,977)	(7,318)
Reclassifications from accumulated other comprehensive loss	1,711	(1,142)
Other comprehensive earnings (loss) net of tax	(4,266)	(8,460)
Balance at the end of the period	$ (17,364)	$ (13,098)