ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS), Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Components of accumulated other comprehensive loss [Roll Forward]
Balance			$ 521,033
Other comprehensive income	$ 1,512	$ 311	4,771	$ 429
Balance	585,939		585,939
AOCI Attributable to Parent [Member]
Components of accumulated other comprehensive loss [Roll Forward]
Balance			(6,849)
Balance	(2,078)		(2,078)
Foreign Currency Translation Adjustment [Member]
Components of accumulated other comprehensive loss [Roll Forward]
Balance			(6,707)
Other comprehensive income			4,740
Balance	(1,967)		(1,967)
Postretirement Benefit Plan [Member]
Components of accumulated other comprehensive loss [Roll Forward]
Balance			(142)
Other comprehensive income			31
Balance	$ (111)		$ (111)