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Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
--- | --- | --- | ---
Income Taxes [Abstract] |  |  |
Bad debt |  | $ 68 |
Valuation allowance |  | (68) |
Total deferred tax assets - current |  |  |
Net operating loss carryforwards | 8,187 | 10,339 |
Oil and gas properties | 2,735 | 4,445 |
Property, Plant and Equipment | 419 | 646 |
Asset retirement obligation | 616 | 801 |
Tax credits | 260 | 260 |
Miscellaneous | 92 | 78 |
Valuation allowance | (12,067) | (16,569) | $ (15,000)
Total deferred tax assets - noncurrent | 242 |  |
Net deferred tax asset | $ 242 |  |

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