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Derivative Instruments (Details 2) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Energy contracts and options [Member] | Direct cost of revenues [Member] |  |  |
Effects of derivative instruments on the consolidated statements of operations |  |  |
Amount of Gain (Loss) Recognized on Derivatives | $ (1,772) | $ (1,674) | $ 1,177

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- Definition Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959 + Details
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- References No definition available. + Details
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