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Derivative Instruments (Details 1) - Energy contracts and options [Member] - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Other current assets [Member]
Schedule of fair value of outstanding derivative instruments recorded as assets and liability
Asset Derivatives not designated or not qualifying as hedging instruments	$ 2,485	$ 4,358
Other current liabilities [Member]
Schedule of fair value of outstanding derivative instruments recorded as assets and liability
Liability Derivatives not designated or not qualifying as hedging instruments	$ 701	$ 1,228

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- References

No definition available.

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- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

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- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as a liability.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

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