Annual report pursuant to Section 13 and 15(d)

Supplemental Information On Oil And Gas Exploration And Production Activities (Costs Incurred In Oil and Gas Property Acquisition and Development Activities) (Details)

v2.4.1.9
Supplemental Information On Oil And Gas Exploration And Production Activities (Costs Incurred In Oil and Gas Property Acquisition and Development Activities) (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]      
Acquisition $ 440,288us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties $ 338,153us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties $ 513,904us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties
Development of proved undeveloped properties 864,511us-gaap_CostsIncurredDevelopmentCosts 408,121us-gaap_CostsIncurredDevelopmentCosts 121,787us-gaap_CostsIncurredDevelopmentCosts
Exploratory 2,249us-gaap_CostsIncurredExplorationCosts 26,174us-gaap_CostsIncurredExplorationCosts 93,397us-gaap_CostsIncurredExplorationCosts
Recompletions 45,658gpor_CostsIncurredRecompletionsOfOilAndGasProperties 44,633gpor_CostsIncurredRecompletionsOfOilAndGasProperties 24,643gpor_CostsIncurredRecompletionsOfOilAndGasProperties
Capitalized asset retirement obligation 2,095us-gaap_CostsIncurredAssetRetirementObligationIncurred 3,556us-gaap_CostsIncurredAssetRetirementObligationIncurred 2,195us-gaap_CostsIncurredAssetRetirementObligationIncurred
Total 1,354,801gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities 820,637gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities 755,926gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities
Diamondback Energy, Inc [Member]      
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]      
Acquisition 0us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
44,534us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
49,895us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
Development of proved undeveloped properties 0us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
6,369us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
22,740us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
Exploratory 0us-gaap_CostsIncurredExplorationCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
17,491us-gaap_CostsIncurredExplorationCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
3,755us-gaap_CostsIncurredExplorationCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
Capitalized asset retirement obligation 0us-gaap_CostsIncurredAssetRetirementObligationIncurred
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
50us-gaap_CostsIncurredAssetRetirementObligationIncurred
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
203us-gaap_CostsIncurredAssetRetirementObligationIncurred
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
Total 0gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
68,444gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
76,593gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_DiamondbackEnergyIncMember
Grizzly Oil Sands ULC [Member]      
Costs Incurred, Oil and Gas Property Acquisition, Exploration, and Development Activities [Line Items]      
Acquisition 1,230us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
0us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
0us-gaap_CostsIncurredAcquisitionOfOilAndGasProperties
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
Development of proved undeveloped properties 7,107us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
0us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
0us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
Exploratory 0us-gaap_CostsIncurredExplorationCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
0us-gaap_CostsIncurredExplorationCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
0us-gaap_CostsIncurredExplorationCosts
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
Capitalized asset retirement obligation 1,055us-gaap_CostsIncurredAssetRetirementObligationIncurred
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
0us-gaap_CostsIncurredAssetRetirementObligationIncurred
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
0us-gaap_CostsIncurredAssetRetirementObligationIncurred
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
Total $ 9,392gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
$ 0gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember
$ 0gpor_TotalCostsIncurredInOilAndGasPropertiesAcquisitionAndDevelopmentActivities
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= gpor_GrizzlyOilSandsUlcMember