CWP and Workers Comp (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic (benefit) cost		$ 93,799,000	$ 52,446,000	$ 71,470,000
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Actuarial Net (Gains) Losses		86,481,000	106,299,000	119,262,000
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax		(367,610,000)	(824,103,000)
Defined Benefit Plan, Assumptions Used in Calculations [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	4.57%		4.51%
Coal Workers Pneumoconiosis [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Curtailments		49,652,000
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		8,168,000	7,711,000	7,620,000
Interest cost		7,031,000	7,964,000	9,330,000
Amortization of actuarial gain		16,384,000	19,338,000	21,182,000
State administrative fees and insurance bond premiums		0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost		(119,881,000)	0	0
Legal and administrative costs		8,168,000	7,711,000
Net periodic (benefit) cost		(121,066,000)	(4,058,000)	(4,960,000)
Legal and administrative costs		8,168,000	7,711,000
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Benefit Obligation		121,183,000	184,079,000	183,580,000
Defined Benefit Plan, Actuarial Net (Gains) Losses		(18,020,000)	(3,919,000)
Defined Benefit Plan, Benefits Paid		(10,423,000)	(11,257,000)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent		111,971,000	(114,136,000)
Defined Benefit Plan, Amounts Recognized in Balance Sheet		(121,183,000)	(184,079,000)
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities		(9,212,000)	(8,838,000)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax		(80,363,000)	(148,955,000)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax		(80,363,000)	(148,955,000)
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract]
Defined Benefit Plan, Amortization of Net Gains (Losses)		(6,196,000)
Defined Benefit Plan, Amortization of Net Prior Service Cost (Credit)		0	(395,000)	(728,000)
Defined Benefit Plan, Assumptions Used in Calculations [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate		4.03%	4.46%	5.21%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		4.75%	4.03%	4.46%
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments in Year One		9,211,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Two		9,204,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Three		9,185,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Four		9,163,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Five		9,156,000
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter		45,090,000
Defined Benefit Plan, Effect of .25% Increase on OPEB costs		(379,000)
defined benefit plan, effect of .25% decrease on OPEB expense		398,000
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax		43,892,000
Deferred Income Taxes and Tax Credits		26,337,000
Workers Compensation [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Curtailments		105,308,000
Defined Benefit Plan, Effect of .25% increase on Pension Benefit Costs		585,000
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost		15,943,000	17,126,000	20,015,000
Interest cost		6,401,000	7,113,000	8,238,000
Amortization of actuarial gain		2,630,000	3,944,000	3,907,000
State administrative fees and insurance bond premiums		5,324,000	6,727,000	7,035,000
Defined Benefit Plan, Net Periodic Benefit Cost		(121,838,000)	0	0
Legal and administrative costs		15,943,000	17,126,000
Net periodic (benefit) cost		(96,800,000)	27,022,000	31,381,000
Legal and administrative costs		15,943,000	17,126,000
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Defined Benefit Plan, Benefit Obligation		85,096,000	179,589,000	174,069,000
Defined Benefit Plan, Actuarial Net (Gains) Losses		11,806,000	6,754,000
Defined Benefit Plan, Benefits Paid		(28,659,000)	(32,200,000)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent		71,468,000	(60,396,000)
Defined Benefit Plan, Amounts Recognized in Balance Sheet		(85,096,000)	(179,589,000)
Pension and Other Postretirement Defined Benefit Plans, Current Liabilities		(13,628,000)	(9,176,000)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax		(13,569,000)	(44,535,000)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax		(13,569,000)	(44,535,000)
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract]
Defined Benefit Plan, Amortization of Net Gains (Losses)		(382,000)
Defined Benefit Plan, Amortization of Net Prior Service Cost (Credit)		0	0	0
Defined Benefit Plan, Assumptions Used in Calculations [Abstract]
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate		3.95%	4.40%	5.13%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		4.57%	3.95%	4.40%
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments in Year One		18,635,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Two		18,479,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Three		18,602,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Four		18,815,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Five		19,000,000
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter		99,249,000
Defined Benefit Plan, Effect of .25% Decrease on Pension Benefit Costs		(530,000)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax		13,768,000
Deferred Income Taxes and Tax Credits		8,262,000
Workers Compensation [Member] | Actuarial Benefits [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments in Year One		13,628,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Two		13,347,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Three		13,341,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Four		13,423,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Five		13,473,000
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter		69,471,000
Workers Compensation [Member] | Other Workers Comp benefits [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
Defined Benefit Plan, Expected Future Benefit Payments in Year One		5,007,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Two		5,132,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Three		5,261,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Four		5,392,000
Defined Benefit Plan, Expected Future Benefit Payments in Year Five		5,527,000
Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter		29,778,000
Discontinued Operations [Member] | Coal Workers Pneumoconiosis [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Defined Benefit Plan, Net Periodic Benefit Cost				(2,887,000)
Net periodic (benefit) cost		(120,496,000)	(2,374,000)
Discontinued Operations [Member] | Workers Compensation [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Net periodic (benefit) cost		$ (113,097,000)	$ 10,132,000	$ 12,722,000