Fair Value Measurements (Details) (USD $)
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3 Months Ended | ||
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Mar. 31, 2015
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Mar. 31, 2014
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Dec. 31, 2014
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Asset retirement obligation capitalized | $ 1,584,000us-gaap_AssetRetirementObligationLiabilitiesIncurred | $ 1,869,000us-gaap_AssetRetirementObligationLiabilitiesIncurred | |
Mammoth Energy Partners LP [Member] | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Equity investment |
143,500,000us-gaap_EquityMethodInvestmentsFairValueDisclosure / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |
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Level 1 [Member] | Fixed Price Swaps [Member] | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Fixed price swaps |
134,986,000us-gaap_DerivativeAssets / us-gaap_DerivativeInstrumentRiskAxis = gpor_FixedPriceSwapsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
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Fixed price swaps |
823,000us-gaap_DerivativeLiabilities / us-gaap_DerivativeInstrumentRiskAxis = gpor_FixedPriceSwapsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel1Member |
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Level 2 [Member] | Fixed Price Swaps [Member] | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Fixed price swaps |
0us-gaap_DerivativeAssets / us-gaap_DerivativeInstrumentRiskAxis = gpor_FixedPriceSwapsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
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Fixed price swaps |
0us-gaap_DerivativeLiabilities / us-gaap_DerivativeInstrumentRiskAxis = gpor_FixedPriceSwapsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel2Member |
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Level 3 [Member] | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Asset retirement obligation capitalized |
1,600,000us-gaap_AssetRetirementObligationLiabilitiesIncurred / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Level 3 [Member] | Mammoth Energy Partners LP [Member] | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Equity investment |
143,500,000us-gaap_EquityMethodInvestmentsFairValueDisclosure / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |
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Level 3 [Member] | Fixed Price Swaps [Member] | |||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | |||
Fixed price swaps |
0us-gaap_DerivativeAssets / us-gaap_DerivativeInstrumentRiskAxis = gpor_FixedPriceSwapsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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Fixed price swaps |
$ 0us-gaap_DerivativeLiabilities / us-gaap_DerivativeInstrumentRiskAxis = gpor_FixedPriceSwapsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member |
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- Definition
Amount of asset retirement obligations incurred during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Fair value portion of investments accounted under the equity method. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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