ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
AOCI Attributable to Parent [Roll Forward]
OCI Before Reclassifications			$ 2,000	$ (900)
Amounts Reclassified from AOCI			3,400	3,300
Net OCI	$ 2,142	$ (794)	5,415	2,347
Total
AOCI Attributable to Parent [Roll Forward]
Beginning balance			(66,400)	(65,300)
Ending balance	(61,000)	(62,900)	(61,000)	(62,900)
Qualified Cash Flow Hedging Instruments
AOCI Attributable to Parent [Roll Forward]
Beginning balance			(6,200)	(8,200)
OCI Before Reclassifications			0	0
Amounts Reclassified from AOCI			1,200	1,100
Net OCI			1,200	1,100
Ending balance	(5,000)	(7,100)	(5,000)	(7,100)
Unrealized Losses on Marketable Securities
AOCI Attributable to Parent [Roll Forward]
Beginning balance			0	400
OCI Before Reclassifications			(600)	2,600
Amounts Reclassified from AOCI			0	0
Net OCI			(600)	2,600
Ending balance	(600)	3,000	(600)	3,000
Defined Benefit Plans
AOCI Attributable to Parent [Roll Forward]
Beginning balance			(60,200)	(57,500)
OCI Before Reclassifications			2,600	(3,500)
Amounts Reclassified from AOCI			2,200	2,200
Net OCI			4,800	(1,300)
Ending balance	$ (55,400)	$ (58,800)	$ (55,400)	$ (58,800)