Basis of Presentation Reclassification of adjustments out of Accumulated Other Comprehensive Loss (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Natural Gas Swaps	$ (31,594)	$ (38,379)	$ 9,263	$ (93,146)
Tax Benefit of Natural Gas Swaps	12,084	14,025	(5,509)	36,551
Natural Gas Swaps, Net of Tax	(19,510)	(24,354)	3,754	(56,595)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	(2,542)	(8,212)	(7,625)	(24,635)
Defined Benefit Plan, Amortization of Gains (Losses)	11,198	21,055	32,705	69,802
Defined Benefit Plan, Curtailments	(36,182)	0	(36,182)	0
Other Comprehensive Income (Loss), Finalization of Pension and Non-Pension Postretirement Plan Valuation, Net of Tax	4,785	6,296	25,492	38,498
Net periodic (benefit) cost	(22,741)	19,139	14,390	83,665
Tax Expense on Actuarially Determined Long-Term Liabilities	8,376	(7,306)	(5,300)	(31,936)
Actuarially Determined Long-Term Liability Adjustments, Net of Tax	$ (14,365)	$ 11,833	$ 9,090	$ 51,729