ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
AOCI Attributable to Parent [Roll Forward]
OCI Before Reclassifications					$ 3,700	$ 2,000
Amounts Reclassified from AOCI					2,700	3,400
Other Comprehensive Income, Net of Tax	$ 4,163	$ 2,196	$ 2,142	$ 3,273	6,359	5,415
Total
AOCI Attributable to Parent [Roll Forward]
Balance		(60,000)		(66,400)	(60,000)	(66,400)
Other Comprehensive Income, Net of Tax	4,163	2,196	2,142	3,273
Balance	(53,600)		(61,000)		(53,600)	(61,000)
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					600	1,200
Other Comprehensive Income, Net of Tax					600	1,200
Balance	(3,800)		(5,000)		(3,800)	(5,000)
Unrealized Gains/(Losses) on Marketable Securities
AOCI Attributable to Parent [Roll Forward]
Balance		(500)		0	(500)	0
OCI Before Reclassifications					1,100	(600)
Amounts Reclassified from AOCI					0	0
Other Comprehensive Income, Net of Tax					1,100	(600)
Balance	600		(600)		600	(600)
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					2,100	2,200
Other Comprehensive Income, Net of Tax					4,700	4,800
Balance	$ (50,400)		$ (55,400)		$ (50,400)	$ (55,400)