ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Changes in 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
Changes in accumulated other comprehensive income (loss) [Abstract]
Net foreign currency translation adjustment	$ 4,313			$ (2,209)			$ 7,440	$ (3,513)
Unrealized gain (loss) on cash flow hedge	299			(769)			(3,585)	(2,475)
Tax	(72)			112			926	519
Net of tax	227			(657)			(2,659)	(1,956)
Net change in postretirement benefit plan (see Note 15 for further information)
Amortization of prior service cost	18			19			56	55
Amortization of gain	(12)			(12)			(38)	(34)
Total before tax	6			7			18	21
Tax	2			(2)			3	(5)
Adjustment	129			0			(455)	0
Net of tax and adjustment	137			5			(434)	16
Other comprehensive gain (loss)	4,677	$ 2,575	$ (2,905)	(2,861)	$ (1,508)	$ (1,084)	4,347	(5,453)
Gain (loss) related to net investment hedge	(3,891)			4,626			(986)	1,715
Tax (expense) benefit on net investment hedge	$ 1,244			$ (456)			$ 330	$ (456)