Property, Plant and Equipment Mine 84 Impairment (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended								12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jun. 30, 2011 Mine Development [Member]	Jun. 30, 2011 airshafts [Member]	Jun. 30, 2011 Machinery and Equipment [Member]	Jun. 30, 2011 Inventories [Member]	Jun. 30, 2011 Prepaid Expenses [Member]	Dec. 31, 2011 Environmental Remediation Expense [Member]
Long-Lived Assets to be Abandoned [Line Items]
Impairment of Long-Lived Assets to be Disposed of	$ 115,817	$ 0	$ 0
Long-Lived Assets to be Abandoned, Carrying Value of Asset				92,136	15,352	2,080	757	385
Environmental Costs of Property for Sale, Disposal or Abandonment, Anticipated Exit Costs									5,107
Noncash Project Abandonment Costs	$ 75,281
Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share	$ 0.33