SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated other comprehensive income (loss)
Beginning Balance	$ 645,649
Unrecognized actuarial gain (loss), net of tax	5,014	$ (2,412)	$ (445)
Foreign currency translation adjustment	(689)	37	(1,041)
Interest rate swap	170	(101)	(187)
Reclassification of foreign currency losses on assets held for sale		6,036
Ending Balance	601,250	645,649
Adjust funded status of pension plan, tax	(100)	100	100
Accumulated Other Comprehensive Income/(Loss)
Accumulated other comprehensive income (loss)
Beginning Balance	278	(3,282)	(1,609)
Unrecognized actuarial gain (loss), net of tax	5,014	(2,412)	(445)
Foreign currency translation adjustment	(689)	37	(1,041)
Interest rate swap	170	(101)	(187)
Reclassification of foreign currency losses on assets held for sale		6,036
Ending Balance	4,773	278	(3,282)
Projected Pension and Postretirement Benefit Obligations
Accumulated other comprehensive income (loss)
Beginning Balance	(570)	1,842	2,287
Unrecognized actuarial gain (loss), net of tax	5,014	(2,412)	(445)
Ending Balance	4,444	(570)	1,842
Translation Adjustment
Accumulated other comprehensive income (loss)
Beginning Balance	997	(5,076)	(4,035)
Foreign currency translation adjustment	(689)	37	(1,041)
Reclassification of foreign currency losses on assets held for sale		6,036
Ending Balance	308	997	(5,076)
Other
Accumulated other comprehensive income (loss)
Beginning Balance	(149)	(48)	139
Interest rate swap	170	(101)	(187)
Ending Balance	$ 21	$ (149)	$ (48)