CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 318,420	$ 369,275	$ 353,396
Net gain (loss) on foreign currency translation	14,508	436	(16,237)
Ending balance	257,696	318,420	369,275
Total Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(25,979)	(42,685)	(20,148)
Ending balance	(18,342)	(25,979)	(42,685)
Foreign currency translation:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(18,022)	(18,458)	(2,221)
Net gain (loss) on foreign currency translation	14,508	436	(16,237)
Other comprehensive income (loss), net of tax	14,508	436	(16,237)
Ending balance	(3,514)	(18,022)	(18,458)
Pension and other postretirement benefit plans:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(3,080)	(22,253)	(18,049)
Net actuarial loss	(2,854)	(222)	(4,998)
Amounts reclassified from accumulated other comprehensive loss	326	19,395	794
Other comprehensive income (loss), net of tax	(2,528)	19,173	(4,204)
Ending balance	(5,608)	(3,080)	(22,253)
Unrealized loss on derivative instruments:
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(4,877)	(1,974)	122
Net loss on derivative instruments	(6,114)	(2,903)	(2,096)
Amounts reclassified from accumulated other comprehensive loss	1,771	0	0
Other comprehensive income (loss), net of tax	(4,343)	(2,903)	(2,096)
Ending balance	$ (9,220)	$ (4,877)	$ (1,974)