ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Attributable to Parent [Roll Forward]
OCI Before Reclassifications							$ 3,900	$ 1,900
Amounts Reclassified from AOCI							4,100	4,900
Other Comprehensive Income (Loss), Net of Tax	$ 1,624	$ 4,163	$ 2,196	$ 1,406	$ 2,142	$ 3,273	7,983	6,821
Total
AOCI Attributable to Parent [Roll Forward]
Balance			(60,000)			(66,400)	(60,000)	(66,400)
Other Comprehensive Income (Loss), Net of Tax	1,624	$ 4,163	2,196	1,406	$ 2,142	3,273
Balance	(52,000)			(59,600)			(52,000)	(59,600)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Balance			(4,400)			(6,200)	(4,400)	(6,200)
OCI Before Reclassifications							0	0
Amounts Reclassified from AOCI							900	1,600
Other Comprehensive Income (Loss), Net of Tax							900	1,600
Balance	(3,500)			(4,600)			(3,500)	(4,600)
Unrealized Gains/(Losses) on Marketable Securities
AOCI Attributable to Parent [Roll Forward]
Balance			(500)			0	(500)	0
OCI Before Reclassifications							1,300	(700)
Amounts Reclassified from AOCI							0	0
Other Comprehensive Income (Loss), Net of Tax							1,300	(700)
Balance	800			(700)			800	(700)
Defined Benefit Plans
AOCI Attributable to Parent [Roll Forward]
Balance			$ (55,100)			$ (60,200)	(55,100)	(60,200)
OCI Before Reclassifications							2,600	2,600
Amounts Reclassified from AOCI							3,200	3,300
Other Comprehensive Income (Loss), Net of Tax							5,800	5,900
Balance	$ (49,300)			$ (54,300)			$ (49,300)	$ (54,300)