ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Components of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 792,523	$ 766,271	$ 743,667	$ 732,345	$ 710,509	$ 691,618	$ 743,667	$ 691,618
Other comprehensive income/(loss)	4,677	2,575	(2,905)	(2,861)	(1,508)	(1,084)	4,347	(5,453)
Ending balance	819,443	792,523	766,271	733,586	732,345	710,509	819,443	733,586
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(5,894)	(8,469)	(5,564)	(6,194)	(4,686)	(3,602)	(5,564)	(3,602)
Other comprehensive income/(loss)	4,677	2,575	(2,905)	(2,861)	(1,508)	(1,084)
Ending balance	(1,217)	$ (5,894)	(8,469)	$ (9,055)	$ (6,194)	$ (4,686)	(1,217)	$ (9,055)
Foreign currency translation adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(5,176)				(5,176)
Other comprehensive income/(loss)							7,440
Ending balance	2,264						2,264
Cash flow hedge
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(1,399)				(1,399)
Other comprehensive income/(loss)							(2,659)
Ending balance	(4,058)						(4,058)
Postretirement benefit plan
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 1,011				1,011
Other comprehensive income/(loss)							(434)
Ending balance	$ 577						$ 577