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Ravenswood impairment (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 | Jun. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015
Impaired Assets to be Disposed of by Method Other than Sale [Line Items] |  |  |  |
Ravenswood charges |  |  | $ 3,830 | $ 30,850
Ravenswood Aluminum Smelter [Member] |  |  |  |
Impaired Assets to be Disposed of by Method Other than Sale [Line Items] |  |  |  |
Ravenswood charges | $ 3,830 | $ 30,850 |  |

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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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=68055307&loc=d3e2420-110228 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585 + Details
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- Definition 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. + Details
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- Details
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