ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, value	$ 941,360	$ 815,750	$ 711,908
Change during the year:
Other comprehensive earnings/(loss)	(5,514)	10,212	49,969
Ending balance, value	1,082,048	941,360	815,750
Interest Rate Swap
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, value	(381)	(277)
Change during the year:
Before-tax amount	516	(141)	(277)
Tax benefit	(135)	37
Other comprehensive earnings/(loss)	381	(104)	(277)
Ending balance, value		(381)	(277)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, value	(322)	(195)	(46,091)
Change during the year:
Before-tax amount		(173)	75,449
Tax benefit		46	(29,553)
Other comprehensive earnings/(loss)		(127)	45,896
Ending balance, value	(322)	(322)	(195)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, value	(10,194)	(20,637)	(24,987)
Change during the year:
Before-tax amount	(5,895)	10,443	4,350
Other comprehensive earnings/(loss)	(5,895)	10,443	4,350
Ending balance, value	(16,089)	(10,194)	(20,637)
Accumulated Other Comprehensive Income/(Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, value	(10,897)	(21,109)	(71,078)
Change during the year:
Before-tax amount	(5,379)	10,129	79,522
Tax benefit	(135)	83	(29,553)
Other comprehensive earnings/(loss)	(5,514)	10,212	49,969
Ending balance, value	$ (16,411)	$ (10,897)	$ (21,109)