PROPERTY, PLANT AND EQUIPMENT (Book Value of Land and Mineral Rights Disclosure) (Details) - USD ($) $ in Millions |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Property, Plant and Equipment [Abstract] | ||
| Land Rights | $ 12.4 | $ 11.6 |
| Mineral Rights [Abstract] | ||
| Mineral Properties, Gross | 537.2 | 488.9 |
| Mineral Properties, Accumulated Depletion | (119.1) | (112.2) |
| Mineral Properties, Net | $ 418.1 | $ 376.7 |
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- Definition Amount before accumulated depletion of real estate held for productive use, excluding land held for sale. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The accumulated decrease in the carrying value of the mineral properties as a result of mine or mineral production. No definition available.
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- Definition Carrying amount at the balance sheet date of mineral properties, gross of adjustments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Mineral properties, net of adjustments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- References No definition available.
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- References No definition available.
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