Income Taxes Effective Tax Rate Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 Rate	Dec. 31, 2012 Rate	Dec. 31, 2011 Rate
Effective Tax Rate Reconciliation [Abstract]
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount	$ 16,126	$ 142,340	$ 305,524
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Depletion, Amount	(51,104)	(49,572)	(72,577)
Effective Income Tax Rate Reconciliation, Nondeductible Expense, Depletion, Percent	(110.90%)	(12.20%)	(8.30%)
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Amount	2,112	2,112	2,112
Effective Income Tax Rate Reconciliation, Deduction, Medicare Prescription Drug Benefit, Percent	4.60%	0.50%	0.20%
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Amount	5,680	(7,215)	(21,938)
Effective Income Tax Rate Reconciliation, Deduction, Qualified Production Activity, Percent	12.30%	(1.80%)	(2.50%)
Effective Income Tax Rate Reconciliation, Tax Contingency, Amount	(1,406)	6,004	2,257
Effective Income Tax Rate Reconciliation, Tax Contingency, Percent	(3.10%)	1.50%	0.30%
Effective Income Tax Rate Reconciliation, Tax Settlement, Amount	3	(925)	(5,188)
Effective Income Tax Rate Reconciliation, Tax Settlement, Percent	0.00%	(0.20%)	(0.60%)
Effective Income Tax Rate Reconciliation, Tax Settlement, State and Local, Amount	(2,399)	(8,737)	2,926
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent	(5.20%)	(2.10%)	0.30%
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount	(4,659)	0	(22,618)
Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent	(10.10%)	0.00%	(2.60%)
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount	0	1,765	(1,822)
Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Percent	0.00%	0.40%	(0.20%)
Effective Income Tax Rate Reconciliation, Deduction, Other, Amount	2,458	2,956	2,575
Effective Income Tax Rate Reconciliation, Deduction, Other, Percent	5.30%	0.70%	0.30%
Income Tax Expense (Benefit)	$ (33,189)	$ 88,728	$ 191,251
Effective Income Tax Rate Reconciliation, Percent	(72.10%)	21.80%	21.90%