Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Taxes [Abstract]
Alternative minimum tax credit carryforwards	$ 151,404	$ 170,592
Net operating loss carryforwards	324,393	102,355
Reclamation and mine closure	93,914	71,533
Advance royalties		38,557
Plant and equipment		19,846
Acquired sales contracts	44,717	20,120
Other	171,715	90,412
Gross deferred tax assets	786,143	513,415
Valuation allowance	(2,831)	(737)
Total deferred tax assets	783,312	512,678
Deferred tax liabilities, plant and equipment	1,566,769
Deferred development	67,728	76,690
Investment in tax partnerships	66,502	68,538
Other	17,015	13,669
Total deferred tax liabilities	1,718,014	158,897
Net deferred tax asset	(934,702)	353,781
Current liability	42,051	(7,775)
Long-term deferred tax asset	$ (976,753)	$ 361,556