Basis of Presentation (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Asset impairment and mine closure costs	$ 20,482	$ 525,583	$ 20,482	$ 525,583
number of mining complexes closed			4
number of mining complexes temporarily idled			1
Segment, Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of mining complexes operated			3