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ENVIRONMENTAL AND MINE CLOSURE OBLIGATIONS (Narrative) (Details) - USD ($) $ in Millions | Sep. 30, 2015 | Dec. 31, 2014
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Environmental Remediation Obligations [Abstract] |  |
Total environmental and mine closure obligations | $ 215.3 | $ 170.8

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- Definition Environmental Loss Contingency And Mine Reclamation And Closing Liability Current And Noncurrent + References No definition available. + Details
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