|**Commitments and Contingencies Commitments and Contingencies (Tables)** | 12 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
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|**Commitments and Contingencies Disclosure [Abstract]**                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Minimum commitments                                                      | Minimum commitments as ofDecember 31, 2013consist of the following:(millions)Drilling, Equipment,and Purchase ObligationsTransportationand GatheringOperatingLeaseObligationsCapitalLeasePayments(1)Total2014$394$91$42$77$60420152011344982466201610313561663652017213461662632018—13353662522019 and Thereafter—4654002241,089Total$700$1,092$666$581$3,039(1)Annual lease payments, net to our interest, exclude regular maintenance and operational costs. SeeNote 10.  Long-Term Debt.
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|(millions)                                                               |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|2014                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|2015                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|2016                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|2017                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|2018                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|2019 and Thereafter                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Total                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            

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