Annual report pursuant to Section 13 and 15(d)

Condensed Consolidating Financial Information - Condensed Consolidating Statement of Operations (Details)

v2.4.1.9
Condensed Consolidating Financial Information - Condensed Consolidating Statement of Operations (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 12 Months Ended
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Revenues:                      
Total revenues $ 267,697us-gaap_Revenues $ 170,804us-gaap_Revenues $ 114,736us-gaap_Revenues $ 118,029us-gaap_Revenues $ 68,067us-gaap_Revenues $ 69,252us-gaap_Revenues $ 70,434us-gaap_Revenues $ 55,000us-gaap_Revenues $ 671,266us-gaap_Revenues $ 262,753us-gaap_Revenues $ 248,926us-gaap_Revenues
Costs and expenses:                      
Lease operating expenses                 52,191us-gaap_LeaseOperatingExpense 26,703us-gaap_LeaseOperatingExpense 24,308us-gaap_LeaseOperatingExpense
Production taxes                 24,006us-gaap_TaxesExcludingIncomeAndExciseTaxes 26,933us-gaap_TaxesExcludingIncomeAndExciseTaxes 28,957us-gaap_TaxesExcludingIncomeAndExciseTaxes
Midstream gathering and processing                 64,467us-gaap_GasGatheringTransportationMarketingAndProcessingCosts 11,030us-gaap_GasGatheringTransportationMarketingAndProcessingCosts 443us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
Depreciation, depletion and amortization                 265,431us-gaap_DepreciationDepletionAndAmortization 118,880us-gaap_DepreciationDepletionAndAmortization 90,749us-gaap_DepreciationDepletionAndAmortization
General and administrative                 38,290us-gaap_GeneralAndAdministrativeExpense 22,519us-gaap_GeneralAndAdministrativeExpense 13,808us-gaap_GeneralAndAdministrativeExpense
(Gain) loss on sale of assets                 (11)us-gaap_GainLossOnSaleOfOilAndGasProperty 508us-gaap_GainLossOnSaleOfOilAndGasProperty (7,300)us-gaap_GainLossOnSaleOfOilAndGasProperty
Accretion expense                 761us-gaap_AssetRetirementObligationAccretionExpense 717us-gaap_AssetRetirementObligationAccretionExpense 698us-gaap_AssetRetirementObligationAccretionExpense
Total costs and expenses                 445,135us-gaap_OperatingExpenses 207,290us-gaap_OperatingExpenses 151,663us-gaap_OperatingExpenses
INCOME FROM OPERATIONS 129,458us-gaap_OperatingIncomeLoss 53,454us-gaap_OperatingIncomeLoss 18,110us-gaap_OperatingIncomeLoss 25,109us-gaap_OperatingIncomeLoss 2,926us-gaap_OperatingIncomeLoss 15,137us-gaap_OperatingIncomeLoss 22,456us-gaap_OperatingIncomeLoss 14,944us-gaap_OperatingIncomeLoss 226,131us-gaap_OperatingIncomeLoss 55,463us-gaap_OperatingIncomeLoss 97,263us-gaap_OperatingIncomeLoss
OTHER (INCOME) EXPENSE:                      
Interest expense                 23,986us-gaap_InterestExpense 17,490us-gaap_InterestExpense 7,458us-gaap_InterestExpense
Interest income                 (195)us-gaap_InvestmentIncomeInterest (297)us-gaap_InvestmentIncomeInterest (72)us-gaap_InvestmentIncomeInterest
Litigation settlement                 25,500us-gaap_LitigationSettlementExpense 0us-gaap_LitigationSettlementExpense 0us-gaap_LitigationSettlementExpense
Gain on contribution of investments                 (84,470)us-gaap_GainLossOnInvestments 0us-gaap_GainLossOnInvestments 0us-gaap_GainLossOnInvestments
Income from equity method investments                 (139,434)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries (213,058)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries (8,322)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
Total Other (Income) Expense                 (174,613)us-gaap_NonoperatingIncomeExpense (195,865)us-gaap_NonoperatingIncomeExpense (936)us-gaap_NonoperatingIncomeExpense
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES                 400,744us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest 251,328us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest 98,199us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
INCOME TAX EXPENSE 67,757us-gaap_IncomeTaxExpenseBenefit 4,876us-gaap_IncomeTaxExpenseBenefit 31,461us-gaap_IncomeTaxExpenseBenefit 49,247us-gaap_IncomeTaxExpenseBenefit 21,027us-gaap_IncomeTaxExpenseBenefit 23,400us-gaap_IncomeTaxExpenseBenefit 25,514us-gaap_IncomeTaxExpenseBenefit 28,195us-gaap_IncomeTaxExpenseBenefit 153,341us-gaap_IncomeTaxExpenseBenefit 98,136us-gaap_IncomeTaxExpenseBenefit 26,363us-gaap_IncomeTaxExpenseBenefit
INCOME FROM CONTINUING OPERATIONS                 247,403us-gaap_IncomeLossFromContinuingOperations 153,192us-gaap_IncomeLossFromContinuingOperations 71,836us-gaap_IncomeLossFromContinuingOperations
Loss on disposal of Belize properties, net of tax                 0us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax 0us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax 3,465us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
NET INCOME 110,073us-gaap_NetIncomeLoss 6,920us-gaap_NetIncomeLoss 47,852us-gaap_NetIncomeLoss 82,558us-gaap_NetIncomeLoss 24,278us-gaap_NetIncomeLoss 40,527us-gaap_NetIncomeLoss 43,828us-gaap_NetIncomeLoss 44,559us-gaap_NetIncomeLoss 247,403us-gaap_NetIncomeLoss 153,192us-gaap_NetIncomeLoss 68,371us-gaap_NetIncomeLoss
Parent [Member]                      
Revenues:                      
Total revenues                 669,067us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
261,809us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
247,637us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Costs and expenses:                      
Lease operating expenses                 51,238us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
25,971us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
23,644us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Production taxes                 23,803us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
26,848us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
28,874us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Midstream gathering and processing                 64,402us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
10,999us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
432us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Depreciation, depletion and amortization                 265,428us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
118,878us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
90,749us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
General and administrative                 37,846us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
22,359us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
13,602us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(Gain) loss on sale of assets                 (11)us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
508us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(7,300)us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Accretion expense                 761us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
717us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
698us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Total costs and expenses                 443,467us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
206,280us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
150,699us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
INCOME FROM OPERATIONS                 225,600us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
55,529us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
96,938us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
OTHER (INCOME) EXPENSE:                      
Interest expense                 23,986us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
17,490us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
7,458us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Interest income                 (195)us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(297)us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(72)us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Litigation settlement                 25,500us-gaap_LitigationSettlementExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
   
Gain on contribution of investments                 (84,470)us-gaap_GainLossOnInvestments
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
   
Income from equity method investments                 (139,965)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(212,992)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(5,182)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Total Other (Income) Expense                 (175,144)us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
(195,799)us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
2,204us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES                 400,744us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
251,328us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
94,734us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
INCOME TAX EXPENSE                 153,341us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
98,136us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
26,363us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
INCOME FROM CONTINUING OPERATIONS                     68,371us-gaap_IncomeLossFromContinuingOperations
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Loss on disposal of Belize properties, net of tax                     0us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
NET INCOME                 247,403us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
153,192us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
68,371us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember
Guarantor [Member]                      
Revenues:                      
Total revenues                 2,199us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
1,517us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
1,289us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Costs and expenses:                      
Lease operating expenses                 953us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
732us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
664us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Production taxes                 203us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
85us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
83us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Midstream gathering and processing                 65us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
31us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
11us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Depreciation, depletion and amortization                 3us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
2us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
General and administrative                 446us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
159us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
132us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
(Gain) loss on sale of assets                 0us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Accretion expense                 0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Total costs and expenses                 1,670us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
1,009us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
890us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
INCOME FROM OPERATIONS                 529us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
508us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
399us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
OTHER (INCOME) EXPENSE:                      
Interest expense                 0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Interest income                 0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Litigation settlement                 0us-gaap_LitigationSettlementExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
   
Gain on contribution of investments                 0us-gaap_GainLossOnInvestments
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
   
Income from equity method investments                 0gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Total Other (Income) Expense                 0us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES                 529us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
508us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
399us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
INCOME TAX EXPENSE                 0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
INCOME FROM CONTINUING OPERATIONS                     399us-gaap_IncomeLossFromContinuingOperations
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Loss on disposal of Belize properties, net of tax                     3,465us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
NET INCOME                 529us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
508us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
(3,066)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_GuarantorSubsidiariesMember
Non-Guarantor [Member]                      
Revenues:                      
Total revenues                 0us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Costs and expenses:                      
Lease operating expenses                 0us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Production taxes                 0us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Midstream gathering and processing                 0us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Depreciation, depletion and amortization                 0us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
General and administrative                 (2)us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
1us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
74us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(Gain) loss on sale of assets                 0us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Accretion expense                 0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
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0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Total costs and expenses                 (2)us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
1us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
74us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
INCOME FROM OPERATIONS                 2us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(1)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(74)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
OTHER (INCOME) EXPENSE:                      
Interest expense                 0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Interest income                 0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Litigation settlement                 0us-gaap_LitigationSettlementExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
   
Gain on contribution of investments                 0us-gaap_GainLossOnInvestments
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
   
Income from equity method investments                 13,159gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
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2,999gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
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1,512gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Total Other (Income) Expense                 13,159us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
2,999us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
1,512us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES                 (13,157)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(3,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
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(1,586)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
INCOME TAX EXPENSE                 0us-gaap_IncomeTaxExpenseBenefit
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0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
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0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
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INCOME FROM CONTINUING OPERATIONS                     (1,586)us-gaap_IncomeLossFromContinuingOperations
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= us-gaap_NonGuarantorSubsidiariesMember
Loss on disposal of Belize properties, net of tax                     0us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
NET INCOME                 (13,157)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(3,000)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
(1,586)us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_NonGuarantorSubsidiariesMember
Eliminations [Member]                      
Revenues:                      
Total revenues                 0us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
(573)us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_Revenues
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Costs and expenses:                      
Lease operating expenses                 0us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_LeaseOperatingExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Production taxes                 0us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
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0us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
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0us-gaap_TaxesExcludingIncomeAndExciseTaxes
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Midstream gathering and processing                 0us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
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0us-gaap_GasGatheringTransportationMarketingAndProcessingCosts
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Depreciation, depletion and amortization                 0us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_DepreciationDepletionAndAmortization
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
General and administrative                 0us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
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0us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_GeneralAndAdministrativeExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
(Gain) loss on sale of assets                 0us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
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0us-gaap_GainLossOnSaleOfOilAndGasProperty
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= us-gaap_ConsolidationEliminationsMember
0us-gaap_GainLossOnSaleOfOilAndGasProperty
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Accretion expense                 0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_AssetRetirementObligationAccretionExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Total costs and expenses                 0us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_OperatingExpenses
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
INCOME FROM OPERATIONS                 0us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
(573)us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_OperatingIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
OTHER (INCOME) EXPENSE:                      
Interest expense                 0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_InterestExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Interest income                 0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_InvestmentIncomeInterest
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Litigation settlement                 0us-gaap_LitigationSettlementExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
   
Gain on contribution of investments                 0us-gaap_GainLossOnInvestments
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
   
Income from equity method investments                 (12,628)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
(3,065)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
(4,652)gpor_IncomeLossfromEquityMethodInvestmentsandInvestmentsinSubsidiaries
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Total Other (Income) Expense                 (12,628)us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
(3,065)us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
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(4,652)us-gaap_NonoperatingIncomeExpense
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES                 12,628us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
2,492us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
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4,652us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
INCOME TAX EXPENSE                 0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
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0us-gaap_IncomeTaxExpenseBenefit
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
INCOME FROM CONTINUING OPERATIONS                     4,652us-gaap_IncomeLossFromContinuingOperations
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
Loss on disposal of Belize properties, net of tax                     0us-gaap_DiscontinuedOperationGainLossOnDisposalOfDiscontinuedOperationNetOfTax
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
NET INCOME                 $ 12,628us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
$ 2,492us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember
$ 4,652us-gaap_NetIncomeLoss
/ dei_LegalEntityAxis
= us-gaap_ConsolidationEliminationsMember