Quarterly report pursuant to Section 13 or 15(d)

Environmental and Mine Closure Obligations (Narrative) (Details)

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Environmental and Mine Closure Obligations (Narrative) (Details) (USD $)
In Millions
Jun. 30, 2011
Dec. 31, 2010
Environmental and Mine Closure Obligations    
Environmental and mine closure liabilities $ 221.8 $ 199.1