STOCKHOLDERS' EQUITY AND ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Summary (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 264,550	$ 253,577	$ 257,696	$ 318,420
Comprehensive income (loss)	8,737	(1,396)	14,200	(66,997)
Stock repurchased	0	0	(201)	(8)
Stock issued under employee plans	151	1	793	32
Stock-based compensation expense	1,363	720	2,313	1,455
Stock issued to directors	398	360	398	360
Balance at end of period	275,199	253,262	275,199	253,262
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	264,550	253,577	257,696	318,420
Net gain (loss) on foreign currency translation	3,060	5,146	46	(4,811)
Balance at end of period	275,199	253,262	275,199	253,262
Loss reclassified from AOCI for defined benefit pension plans	(100)		(100)	(100)
Tax benefit reclassified from AOCI for defined benefit pension plans			(100)	(100)
AOCI Attributable to Parent
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at end of period	(15,016)	(30,698)	(15,016)	(30,698)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at end of period	(15,016)	(30,698)	(15,016)	(30,698)
Impact of de-designation of interest rate swap agreement	600	(100)	(400)	(100)
Foreign Currency Translation
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(6,528)	(27,979)	(3,514)	(18,022)
Balance at end of period	(3,468)	(22,833)	(3,468)	(22,833)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(6,528)	(27,979)	(3,514)	(18,022)
Net gain (loss) on foreign currency translation	3,060	5,146	(988)	(4,811)
Amounts reclassified from accumulated other comprehensive income	0	0	1,034	0
Other comprehensive income (loss), net of tax	3,060	5,146	46	(4,811)
Balance at end of period	(3,468)	(22,833)	(3,468)	(22,833)
Tax benefit of reclassification of accumulated loss on foreign currency translation			(200)
Pension and Other Postretirement Benefit Plans
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(5,243)	(2,749)	(5,608)	(3,080)
Balance at end of period	(5,221)	(2,749)	(5,221)	(2,749)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(5,243)	(2,749)	(5,608)	(3,080)
Amounts reclassified from accumulated other comprehensive income	22	0	387	331
Other comprehensive income (loss), net of tax	22	0	387	331
Balance at end of period	(5,221)	(2,749)	(5,221)	(2,749)
Loss reclassified from AOCI for defined benefit pension plans			(400)	(400)
Tax benefit reclassified from AOCI for defined benefit pension plans			(100)	(100)
Unrealized gain/(loss) on derivative instruments
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(6,202)	(4,431)	(9,220)	(4,877)
Balance at end of period	(6,327)	(5,116)	(6,327)	(5,116)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at beginning of period	(6,202)	(4,431)	(9,220)	(4,877)
Net loss on derivative instruments	(696)	(1,082)	1,704	(636)
Amounts reclassified from accumulated other comprehensive income	571	397	1,189	397
Other comprehensive income (loss), net of tax	(125)	(685)	2,893	(239)
Balance at end of period	(6,327)	(5,116)	(6,327)	(5,116)
Taxes on unrealized losses on the fair value of hedging activities	$ 200	$ 300	$ 500	$ 200