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Supplemental Information On Oil And Gas Exploration And Production Activities (Results Of Operations For Producing Activities) (Details) (USD $) | 12 Months Ended
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Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Oil and Gas Exploration and Production Industries Disclosures [Abstract] |  |  |
Revenues | $ 248,601,000 | $ 228,953,000 | $ 127,636,000
Production costs | (53,708,000) | (47,230,000) | (31,580,000)
Depletion | (90,230,000) | (61,965,000) | (38,600,000)
Income before income taxes (benefit) | 104,663,000 | 119,758,000 | 57,456,000
Current | 730,000 | 282,000 | 40,000
Deferred | 25,633,000 | (372,000) | 0
Income tax expense (benefit) | 26,363,000 | (90,000) | 40,000
Results of operations from producing activities | 78,300,000 | 119,848,000 | 57,416,000
Depletion per barrel of oil equivalent (BOE) | $ 35.07 | $ 26.56 | $ 19.54

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- Definition Depreciation, depletion and amortization, and valuation provisions (impairments) related to oil and gas producing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59S -Subparagraph d -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition Income before income taxes for oil and gas producing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59S -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition Production (lifting) costs from oil and gas producing activities, including but not limited to lease operating expense, production and ad valorem taxes, and transportation expense. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 23 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62136-109447 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 19 -Paragraph 59S -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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