4. Derivatives - Schedule of Derivatives Not Designated as Hedging Instruments (Details) - USD ($) $ in Thousands |
Jun. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Commodity contracts - Derivative assets | $ 13,299 | $ 2,081 |
| Commodity contracts - Derivative liabilities | 12,166 | 1,848 |
| Commodity Contracts [Member] | Non Designated Derivative Instruments [Member] | ||
| Commodity contracts - Derivative assets | 13,299 | 2,081 |
| Commodity contracts - Derivative liabilities | $ 12,166 | $ 1,848 |
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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