ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 766,271	$ 743,667	$ 710,509	$ 691,618	$ 743,667	$ 691,618
Other comprehensive income/(loss)	2,575	(2,905)	(1,508)	(1,084)	(330)	(2,592)
Ending balance	792,523	766,271	732,345	710,509	792,523	732,345
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(8,469)	(5,564)	(4,686)	(3,602)	(5,564)	(3,602)
Other comprehensive income/(loss)	2,575	(2,905)	(1,508)	(1,084)
Ending balance	(5,894)	(8,469)	$ (6,194)	$ (4,686)	(5,894)	$ (6,194)
Foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(5,176)			(5,176)
Other comprehensive income/(loss)					3,127
Ending balance	(2,049)				(2,049)
Cash flow hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(1,399)			(1,399)
Other comprehensive income/(loss)					(2,886)
Ending balance	(4,285)				(4,285)
Postretirement benefit plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 1,011			1,011
Other comprehensive income/(loss)					(571)
Ending balance	$ 440				$ 440