ACCUMULATED OTHER COMPREHENSIVE LOSS (AOCL) - RECLASSIFICATIONS OUT OF AOCL (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Operations									$ 151,957	$ 148,672	$ 140,260
Income Taxes	$ 19,266	$ 2,807	$ (7,189)	$ 39,267	$ (1,006)	$ (10,968)	$ (3,279)	$ 16,613	54,151	1,360	4,449
Net Income									(118,810)	(105,107)	(97,046)
Income from Continuing Operations	$ (46,008)	$ (9,664)	$ 4,798	$ (68,187)	$ (50,948)	$ 12,532	$ (13,341)	$ (53,853)	(119,061)	$ (105,610)	$ (97,628)
Losses from reclassifications for the period net of tax									$ 2,412
Combined average statutory tax rate									40.00%
Unrealized Gain (Loss) on Available- for-Sale Securities
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Losses from reclassifications for the period net of tax									$ (205)
Amounts Reclassified from AOCL | Actuarial Loss on Postretirement Benefits
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Operations									4,001
Income Taxes									(1,581)
Income from Continuing Operations									2,420
Amounts Reclassified from AOCL | Unrealized Loss on Derivatives-Other - interest rate contracts designated as cash flow hedges
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Income Taxes									(136)
Net Income									197
Amounts Reclassified from AOCL | Unrealized Gain (Loss) on Available- for-Sale Securities
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Other Income									(342)
Income Taxes									137
Net Income									(205)
Amounts Reclassified from AOCL | Interest rate contract | Unrealized Loss on Derivatives-Other - interest rate contracts designated as cash flow hedges
Reclassification out of Accumulated Other Comprehensive Income [Line Items]
Interest Charges									$ 333