Taxes Taxes (Schedule of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Taxes [Abstract]
Alternative Minimum Tax Credit Carryforwards	$ 496,330	$ 324,393
Net Operating Loss Carryforwards	150,014	151,404
Reclamation and mine closure	104,570	93,914
Deferred Tax Assets, Goodwill and Intangible Assets	43,839	0
Advance royalties	32,241	26,266
Plant And Equipment	32,087	24,456
Acquired sales contracts	38,735	44,717
Other	113,777	120,993
Gross Deferred Tax Assets	1,011,593	786,143
Valuation Allowance	(34,663)	(2,831)
Total Deferred Tax Assets	976,930	783,312
Deferred Tax Liabilities, Plant And Equipment	1,411,446	1,566,769
Deferred Development	77,013	67,728
Investment in tax partnerships	72,513	66,502
Other	12,780	17,015
Tota Deferred Tax Liabilities	1,573,752	1,718,014
Net Deferred Tax Asset	(596,822)	(934,702)
Current liability	67,360	42,051
Long-term Deferred Tax Asset	$ (664,182)	$ (976,753)