ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
AOCI Attributable to Parent [Roll Forward]
OCI Before Reclassifications	$ 700	$ (400)
Amounts Reclassified from AOCI	1,500	3,700
Other Comprehensive Income, Net of Tax	2,196	3,273
Total
AOCI Attributable to Parent [Roll Forward]
Balance	(60,000)	(66,400)
Other Comprehensive Income, Net of Tax	2,196	3,273
Balance	(57,800)	(63,100)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Balance	(4,400)
OCI Before Reclassifications	0
Amounts Reclassified from AOCI	300
Other Comprehensive Income, Net of Tax	300
Balance	(4,100)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Balance		(6,200)
OCI Before Reclassifications		0
Amounts Reclassified from AOCI		700
Other Comprehensive Income, Net of Tax		700
Balance		(5,500)
Unrealized Gains/(Losses) on Marketable Securities
AOCI Attributable to Parent [Roll Forward]
Balance	(500)	0
OCI Before Reclassifications	700	(400)
Amounts Reclassified from AOCI	0	0
Other Comprehensive Income, Net of Tax	700	(400)
Balance	200	(400)
Defined Benefit Plans
AOCI Attributable to Parent [Roll Forward]
Balance	(55,100)	(60,200)
OCI Before Reclassifications	0	0
Amounts Reclassified from AOCI	1,200	3,000
Other Comprehensive Income, Net of Tax	1,200	3,000
Balance	$ (53,900)	$ (57,200)