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Derivative Instruments (Details 1) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Schedule of fair value of outstanding derivative instruments recorded as assets and liability
Liability Derivatives, not designated or not qualifying as hedging instruments	$ 2,546	$ 1,727
Energy contracts and options [Member] | 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	4,842	2,651
Energy contracts and options [Member] | Energy hedging contracts [Member]
Schedule of fair value of outstanding derivative instruments recorded as assets and liability
Liability Derivatives, not designated or not qualifying as hedging instruments	$ 2,546	$ 1,727

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- References

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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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=64837297&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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624163-113959

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