Asset Realization (Narrative) (Details) - Carlisle Assets [Member] $ in Thousands, T in Millions	9 Months Ended
Sep. 30, 2015 USD ($) T
Impairment Effects on Earnings Per Share [Line Items]
Mine carring value	$ 177,000
Asset impairment charge	$ 0
Asset impairment assumption, normal production capacity per year \| T	3

Asset impairment assumption, normal production capacity per year

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Mineral properties, net of adjustments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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