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DERIVATIVE INSTRUMENTS (Details 4) lb in Millions | Dec. 31, 2017 lb oz | Dec. 31, 2016 lb oz
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Volumes subject to final pricing net of outstanding swaps [Abstract] |  |
Gold ounces | oz | 2,000 | 4,000
Copper pounds | lb | 1.6 | 3.0

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- Definition The volume of copper subject to final pricing net of outstanding swaps. + References No definition available. + Details
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- Definition The volume of gold subject to final pricing net of outstanding swaps. + References No definition available. + Details
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