Income Taxes (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets
Net operating loss carryforward, patronage - sourced		$ 94,300,000
Other net operating loss carryforwards	96,000,000	70,800,000
Retirement and other employee benefits	71,500,000	92,100,000
Asset retirement obligations		31,800,000
Unrealized loss on investments		200,000
Intangible asset	115,300,000
Federal tax settlement	43,700,000
Other	70,500,000	56,700,000
Gross deferred tax assets	397,000,000	345,900,000
Valuation allowance	(109,200,000)	(176,100,000)
Net deferred tax assets	287,800,000	169,800,000
Deferred tax liabilities
Depreciation and amortization	(921,000,000)	(968,000,000)
Foreign earnings	(35,400,000)	(24,400,000)
Deferred patronage from CFL		(1,700,000)
Depletable mineral properties	(45,900,000)	(46,700,000)
Unrealized gain on hedging derivatives	(14,600,000)	(3,300,000)
Other	(44,100,000)	(55,000,000)
Deferred tax liabilities	(1,061,000,000)	(1,099,100,000)
Net deferred tax liability	(773,200,000)	(929,300,000)
Less amount in current assets (liabilities)	60,000,000	9,500,000
Noncurrent liability	(833,200,000)	(938,800,000)
Unrecognized tax benefits:
Beginning balance	154,400,000	137,100,000
Additions for tax positions taken during the current year	9,600,000	17,300,000
Additions for tax positions taken during prior year	25,000,000
Reductions related to lapsed statutes of limitations	(1,300,000)
Reductions related to settlements with tax jurisdictions	(84,000,000)
Ending balance	103,700,000	154,400,000
Decrease in unrecognized tax benefits	50,700,000
Effect on effective tax rate if unrecognized tax benefits were recognized	103,700,000
Tax benefit for the effect of a Closing Agreement with the IRS	75,800,000
Tax savings payable to pre-IPO owners	55,200,000
Current portion of the tax savings payable to the pre-IPO owners	10,200,000
Non current portion of the tax savings payable to the pre-IPO owners	32,700,000
Period of entitlement of tax deduction equal to portion of NOL	5 years
Decrease in unrecognized tax benefits	86,700,000
Repatriation of investment in the entity's non-U.S. subsidiaries and corporate joint ventures which is considered to be permanently reinvested	$ 1,000,000,000
Percentage of retention of any settlement realized with the United States Internal Revenue Service (IRS) at the IRS Appeals level	26.90%