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Supplemental Information On Oil And Gas Exploration And Production Activities (Narrative) (Details) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2012 MBoe | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2010
Oil and Gas Exploration and Production Industries Disclosures [Abstract] |  |  |  |  |  |
Prices per unit (usd per MMbls or MMcf) | 2.76 | 91.32 | 96.19 | 4.12 | 76.16 | 4.38
Decrease in reserve during the period | (12,564) | (12,564) |  |  |  |
Decrease in reserves relating to change in estimates | 442 | 442 |  |  |  |
Future development costs estimated to be spent in 2013 |  | $ 82,772 |  |  |  |
Future development costs estimated to be spent in 2014 |  | 16,416 |  |  |  |
Future development costs estimated to be spent in 2015 |  | $ 4,335 |  |  |  |

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- Definition The revenues derived from sales of oil or gas in each geographic area during the reporting period divided by the number of barrels of oil produced or thousands of cubic feet of gas produced. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Industry Guide -Number 2 -Paragraph 3 -Subparagraph A + Details
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