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Derivatives And Fair Value (Derivative Instruments Accounted For At Fair Value On A Recurring Basis) (Details) - Commodity Contract [Member] - Not Designated as Hedging Instrument [Member] - Prepayments and other [Member] - USD ($) $ in Thousands | Sep. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Derivatives, Fair Value [Line Items] |  |
Derivative instruments | $ 61 | $ 1,227
Fair Value, Inputs, Level 1 [Member] |  |
Derivatives, Fair Value [Line Items] |  |
Derivative instruments |  |
Fair Value, Inputs, Level 2 [Member] |  |
Derivatives, Fair Value [Line Items] |  |
Derivative instruments | 61 | 1,227
Fair Value, Inputs, Level 3 [Member] |  |
Derivatives, Fair Value [Line Items] |  |
Derivative instruments |  |

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- Definition Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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