ACCUMULATED OTHER COMPREHENSIVE LOSS (AOCL) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1	[1]	$ (30,258)
Other comprehensive income before reclassifications		1,351
Amounts reclassified from AOCL	[2]	4,408
Other Comprehensive (Loss) Income - Net of Tax	[3]	5,759		$ (9,498)		$ 10,345
Balance at December 31	[1]	$ (24,499)		$ (30,258)
Combined statutory tax rate		40.00%		40.00%		41.00%
Postretirement Liability Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1	[3]	$ (27,663)	[1]	$ (18,503)		$ (23,437)
Other comprehensive income before reclassifications		1,427
Amounts reclassified from AOCL	[2]	4,091
Other Comprehensive (Loss) Income - Net of Tax	[3]	5,518		(9,160)		4,934
Balance at December 31	[3]	(22,145)	[1]	(27,663)	[1]	(18,503)
Unrealized Gain (Loss) on Derivatives-Other [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1	[3]	(2,450)	[1]	(2,697)		(2,962)
Other comprehensive income before reclassifications		0
Amounts reclassified from AOCL	[2]	321
Other Comprehensive (Loss) Income - Net of Tax	[3]	321		247		265
Balance at December 31	[3]	(2,129)	[1]	(2,450)	[1]	(2,697)
Unrealized Gain (Loss) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1	[3]	(75)	[1]	397		294
Other comprehensive income before reclassifications		(76)
Amounts reclassified from AOCL	[2]	23
Other Comprehensive (Loss) Income - Net of Tax	[3]	(53)		(472)		103
Balance at December 31	[3]	(128)	[1]	(75)	[1]	$ 397
Other Comprehensive Income (Loss) of Affiliated Companies [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at January 1	[1]	(70)
Other comprehensive income before reclassifications		0
Amounts reclassified from AOCL	[2]	(27)
Other Comprehensive (Loss) Income - Net of Tax		(27)
Balance at December 31	[1]	$ (97)		$ (70)

[1] Determined using a combined average statutory tax rate of 40%.

[2] See table below.

[3] For 2015 and 2014, determined using a combined average statutory tax rate of 40%. For 2013, determined using a combined statutory tax rate of 41%.