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Ravenswood impairment (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2015 | Jun. 30, 2014 | Jun. 30, 2015 | Jun. 30, 2014
Restructuring Cost and Reserve [Line Items] |  |  |  |
Ravenswood impairment | $ 30,850 | $ 0 | $ 30,850 | $ 0
Write-down of inventory |  |  | 25,689 | $ (1,247)
Employee Severance and Postemployment Benefits [Member] |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |
Expected restructuring cost | $ 1,550 |  | 1,550 |
Ravenswood Aluminum Smelter [Member] |  |  |  |
Restructuring Cost and Reserve [Line Items] |  |  |  |
Ravenswood impairment |  |  | 30,850 |
Impairment of assets |  |  | 21,500 |
Write-down of inventory |  |  | $ 7,800 |

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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=51824106&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=56944662&loc=d3e3602-108585 + Details
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- Definition Charge to cost of goods sold that represents the reduction of the carrying amount of inventory, generally attributable to obsolescence or market conditions. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 330 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28360613&loc=d3e4542-108314 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
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