|**Commitments and Contingencies**                       | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
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|**Commitments and Contingencies Disclosure [Abstract]** |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Commitments and Contingencies                           | Commitments and ContingenciesLegal ProceedingsWe are involved in various legal proceedings in the ordinary course of business.  These proceedings are subject to the uncertainties inherent in any litigation.  We are defending ourselves vigorously in all such matters and we believe that the ultimate disposition of such proceedings will not have a material adverse effect on our financial position, results of operations or cash flows.CONSOL Carried Cost ObligationBased on theDecember 31, 2012Henry Hub natural gas price strip, we forecast our CONSOL Carried Cost Obligation will be suspended throughout the2013fiscal year. Therefore, specific payment dates for funding cannot be determined at this time and are excluded from the minimum commitments table below.  SeeNote 3.  Acquisitions and Divestitures.Non-Cancelable Leases and Other CommitmentsWehold leases and other commitments for drilling rigs, buildings, equipment and other property. Rental expense for office buildings and oil and gas operations equipment was$37 millionin2012,$31 millionin2011, and$27 millionin2010.Minimum commitments as ofDecember 31, 2012consist of the following:Drilling, Equipment,and Purchase ObligationsTransportationand GatheringOperatingLeaseObligationsFPSOLeasePayments(1)Total(millions)2013$739$81$47$72$9392014191784272383201517586527038320161018852452862017—8748451802018 and Thereafter—311302109722Total$1,206$731$543$413$2,893(1)Annual lease payments, net to our interest, exclude regular maintenance and operational costs. SeeNote 12.  Long-Term Debt.
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|(millions)                                              |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
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|2017                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|2018 and Thereafter                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
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|(1)                                                     | Annual lease payments, net to our interest, exclude regular maintenance and operational costs. SeeNote 12.  Long-Term Debt.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                

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