Taxes (Schedule of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Taxes [Abstract]
Alternative Minimum Tax Credit Carryforwards	$ 660,916	$ 496,330
Net Operating Loss Carryforwards	126,755	150,014
Reclamation and mine closure	113,843	104,570
Deferred Tax Assets, Goodwill and Intangible Assets	52,636	43,839
Acquired sales contracts	33,392	38,735
Advance royalties	31,641	32,241
Plant And Equipment	20,527	32,087
Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost	28,494	25,440
Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Accrued Liabilities	19,327	21,798
Other	68,969	66,777
Gross Deferred Tax Assets	1,156,500	1,011,831
Valuation Allowance	(43,322)	(34,663)
Total Deferred Tax Assets	1,113,178	977,168
Deferred Tax Liabilities, Property, Plant and Equipment	1,364,382	1,411,446
Deferred Development	91,126	77,013
Investment in tax partnerships	8,170	72,513
Other	13,902	13,018
Tota Deferred Tax Liabilities	1,477,580	1,573,990
Net Deferred Tax Asset	$ 364,402	$ 596,822