ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
AOCI Attributable to Parent [Roll Forward]
OCI Before Reclassifications	$ (800)	$ (700)
Amounts Reclassified from AOCI	1,500	1,900
Net OCI	704	1,188
Accumulated Other Comprehensive Loss
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(42,300)	(76,400)
Net OCI	704	1,188
Ending balance	(41,600)	(75,200)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(400)	(1,400)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	0	400
Net OCI	0	400
Ending balance	(400)	(1,000)
Unrealized Gains/(Losses) on Marketable Securities
AOCI Attributable to Parent [Roll Forward]
Beginning balance	400	1,100
OCI Before Reclassifications	(800)	(700)
Amounts Reclassified from AOCI	0	0
Net OCI	(800)	(700)
Ending balance	(400)	400
Defined Benefit Plans
AOCI Attributable to Parent [Roll Forward]
Beginning balance	(42,300)	(76,100)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	1,500	1,500
Net OCI	1,500	1,500
Ending balance	$ (40,800)	$ (74,600)