Annual report pursuant to Section 13 and 15(d)

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details)

v3.20.4
ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance $ 815,750 $ 711,908 $ 653,924
Change during 2020:      
Other comprehensive earnings/(loss) 10,212 49,969 (25,122)
Ending Balance 941,360 815,750 711,908
Interest Rate Swap [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance (277)
Change during 2020:      
Before-tax amount (141) (277)
Tax benefit 37
Other comprehensive earnings/(loss) (104) (277)
Ending Balance (381) (277)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance (195) (46,091) (35,041)
Change during 2020:      
Before-tax amount (173) 75,449 (14,812)
Tax benefit 46 (29,553) 3,762
Other comprehensive earnings/(loss) (127) 45,896 (11,050)
Ending Balance (322) (195) (46,091)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance (20,637) (24,987) (10,915)
Change during 2020:      
Before-tax amount 10,443 4,350 (14,072)
Tax benefit
Other comprehensive earnings/(loss) 10,443 4,350 (14,072)
Ending Balance (10,194) (20,637) (24,987)
AOCI Attributable to Parent [Member]      
Accumulated Other Comprehensive Income (Loss) [Line Items]      
Beginning Balance (21,109) (71,078) (45,956)
Change during 2020:      
Before-tax amount 10,129 79,522 (28,884)
Tax benefit 83 (29,553) 3,762
Other comprehensive earnings/(loss) 10,212 49,969 (25,122)
Ending Balance $ (10,897) $ (21,109) $ (71,078)