ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS), Changes in 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
Changes in accumulated other comprehensive income (loss) [Abstract]
Net foreign currency translation adjustment	$ 1,502	$ 302	$ 4,740	$ 850
Net change in postretirement benefit plan (see Note 14 for further information) [Abstract]
Initial adoption of new plan			0	(444)
Amortization of prior service cost	19	16	57	40
Amortization of gain	(4)	(3)	(12)	(8)
Total before tax	15	13	45	(412)
Tax	(5)	(4)	(14)	(9)
Net of tax	10	9	31	(421)
Other comprehensive income	$ 1,512	$ 311	$ 4,771	$ 429