COMPREHENSIVE INCOME - Accumulated other comprehensive loss (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
COMPREHENSIVE INCOME
Foreign currency translation adjustments	$ (7,954)	$ (8,596)	$ (6,783)
Pension liability, net of tax	(9,357)	(11,597)	(18,011)
Total accumulated other comprehensive loss	$ (17,311)	$ (20,193)	$ (24,794)

Amount, after tax, of accumulated increase (decrease) in equity from transaction and other event and circumstance from nonowner source.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant