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Supplemental Oil and Gas Disclosures - Capitalized Costs Related to Oil and Natural Gas (Details) (USD $)
In Millions, unless otherwise specified |
Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Net capitalized cost: | |||
| Proved oil and natural gas properties and equipment | $ 7,924.2us-gaap_CapitalizedCostsMineralInterestsInProvedProperties | $ 7,207.1us-gaap_CapitalizedCostsMineralInterestsInProvedProperties | $ 6,551.5us-gaap_CapitalizedCostsMineralInterestsInProvedProperties |
| Unproved oil and natural gas properties and equipment | 121.5us-gaap_CapitalizedCostsMineralInterestsInUnprovedProperties | 132.0us-gaap_CapitalizedCostsMineralInterestsInUnprovedProperties | 143.0us-gaap_CapitalizedCostsMineralInterestsInUnprovedProperties |
| Accumulated depreciation, depletion and amortization related to oil, NGLs and natural gas activities | (5,557.6)us-gaap_CapitalizedCostsAccumulatedDepreciationDepletionAmortizationAndValuationAllowanceForRelatingToOilAndGasProducingActivities | (5,069.2)us-gaap_CapitalizedCostsAccumulatedDepreciationDepletionAmortizationAndValuationAllowanceForRelatingToOilAndGasProducingActivities | (4,640.8)us-gaap_CapitalizedCostsAccumulatedDepreciationDepletionAmortizationAndValuationAllowanceForRelatingToOilAndGasProducingActivities |
| Net capitalized costs related to producing activities | $ 2,488.1us-gaap_CapitalizedCostsOilAndGasProducingActivitiesNet | $ 2,269.9us-gaap_CapitalizedCostsOilAndGasProducingActivitiesNet | $ 2,053.7us-gaap_CapitalizedCostsOilAndGasProducingActivitiesNet |
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- Definition
Amount of accumulated depreciation, depletion, amortization and valuation allowance relating to oil and gas producing activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Capitalized costs of proved properties that include fee ownership or a lease, concession, or other interest representing the right to extract oil or gas subject to such terms as may be imposed by the conveyance of that interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Capitalized costs of unproven properties that include fee ownership or a lease, concession, or other interest representing the right to extract oil or gas subject to such terms as may be imposed by the conveyance of that interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Net amount of capitalized costs relating to oil and gas producing activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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