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Business segments - Major Customers (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Revenue, Major Customer [Line Items] |  |  |
Major customer, percentage revenue, net | 10.00% |  |
Glencore [Member] |  |  |
Revenue, Major Customer [Line Items] |  |  |
Major customer, Revenue, net | $ 1,178,631 | $ 1,867,711 | $ 1,262,101
Southwire [Member] |  |  |
Revenue, Major Customer [Line Items] |  |  |
Major customer, Revenue, net | $ 0 | $ 0 | $ 226,740

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- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
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- Details
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