Derivative Financial Instruments (Details 2) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Offsetting Derivative Assets [Abstract]
Derivative Liability	$ (15,239)	$ (24,954)
Offsetting Derivative Liabilities [Abstract]
Derivative Asset	0	0
Other Current Assets [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts of recognized assets	131,092
Gross amounts netted in the consolidated balance sheets	(129,902)
Derivative Asset	1,190
Current liabilities [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized liabilities	(146,331)	(24,203)
Gross amounts netted in the consolidated balance sheet	(129,902)	0
Derivative Liability	$ (16,429)	(24,203)
Other liabilities [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts of recognized liabilities		751
Gross amounts netted in the consolidated balance sheet		0
Derivative Liability		$ 751

Fair value of liability associated with financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ References

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+ References

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