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Equity Investments (Narrative) (Details) (USD $) | 12 Months Ended | 9 Months Ended | 0 Months Ended | 1 Months Ended | 3 Months Ended | 1 Months Ended |  |  |  |  |  |  |
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Dec. 31, 2014 acre | Dec. 31, 2013 | Dec. 31, 2012 | Sep. 30, 2012 | Jan. 28, 2014 | Nov. 12, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Nov. 30, 2013 | Jun. 30, 2013 | Sep. 30, 2014 | Dec. 31, 2014 | Feb. 26, 2015 | May 31, 2013 | Dec. 31, 2011 | Jan. 01, 2008 | May 15, 2012 | Jul. 02, 2013 | Dec. 17, 2012 | Oct. 11, 2012
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gas and oil area, reserve (acres) | 243,000 gpor_GasAndOilAreaReserve |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | $ 139,434,000 us-gaap_IncomeLossFromEquityMethodInvestments | $ 213,058,000 us-gaap_IncomeLossFromEquityMethodInvestments | $ 8,322,000 us-gaap_IncomeLossFromEquityMethodInvestments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount put in escrow |  |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000 us-gaap_EscrowDeposit |  |  |  |  |  |
Equity investments | 369,581,000 us-gaap_EquityMethodInvestments | 440,068,000 us-gaap_EquityMethodInvestments |  |  |  |  |  |  |  |  |  | 369,581,000 us-gaap_EquityMethodInvestments |  |  |  |  |  |  |  |
Distributions received | 0 us-gaap_EquityMethodInvestmentDividendsOrDistributions | 1,276,000 us-gaap_EquityMethodInvestmentDividendsOrDistributions | 820,000 us-gaap_EquityMethodInvestmentDividendsOrDistributions |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Advances on note receivable to related party | (875,000)us-gaap_OriginationOfNotesReceivableFromRelatedParties | 875,000 us-gaap_OriginationOfNotesReceivableFromRelatedParties | 0 us-gaap_OriginationOfNotesReceivableFromRelatedParties |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest income | 195,000 us-gaap_InvestmentIncomeInterest | 297,000 us-gaap_InvestmentIncomeInterest | 72,000 us-gaap_InvestmentIncomeInterest |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cumulative translation adjustment | (26,675,000)us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax | (9,781,000)us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax | 2,442,000 us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax |  |  |  |  |  |  |  |  | (26,675,000)us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax |  |  | 1,087,000 us-gaap_AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax |  |  |  |  |
Payments for equity method investments | 63,999,000 us-gaap_PaymentsToAcquireEquityMethodInvestments | 47,014,000 us-gaap_PaymentsToAcquireEquityMethodInvestments | 147,307,000 us-gaap_PaymentsToAcquireEquityMethodInvestments |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Coronado Midstream LLC [Member] | Windsor Midstream LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 28.40%us-gaap_EquityMethodInvestmentOwnershipPercentage / dei_LegalEntityAxis = gpor_WindsorMidstreamLlcMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_CoronadoMidstreamLLCMember |  |  |  |  |  |  |  |  |  |  | 28.40%us-gaap_EquityMethodInvestmentOwnershipPercentage / dei_LegalEntityAxis = gpor_WindsorMidstreamLlcMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_CoronadoMidstreamLLCMember |  |  |  |  |  |  |  |
Tatex Thailand II, LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | 475,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiLlcMember | 343,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiLlcMember | (7,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 23.50%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiLlcMember |  |  |  |  |  |  |  |  |  |  | 23.50%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiLlcMember |  |  |  |  |  |  |  |
Apico Llc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity shares owned by affiliate (shares) | 85,122 gpor_EquitySharesOwnedByAffiliateOfInvestment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_ApicoLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total shares owned of subaffiliate (shares) | 1,000,000 gpor_EquityMethodInvestmentTotalSharesOutstandingOfSubaffiliate / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_ApicoLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tatex Thailand III LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gas and oil area, reserve (acres) | 245,000 gpor_GasAndOilAreaReserve / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | (12,408,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember | (254,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember | (251,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash calls paid | (1,600,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember | (2,400,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 17.90%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember |  |  |  |  |  |  |  |  |  |  | 17.90%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember |  |  |  |  |  |  |  |
Equity investments | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember | 10,774,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember |  |  |  |  |  |  |  |  |  | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember |  |  |  |  |  |  |  |
Grizzly Oil Sands ULC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gas and oil area, reserve (acres) | 830,000 gpor_GasAndOilAreaReserve / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | (13,159,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember | (2,999,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember | (1,512,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash calls paid | (18,800,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember | (33,900,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |  |  |  |  |  |  |  | 25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |  |  |  |  |
Equity investments | 180,218,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember | 191,473,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |  |  |  |  |  |  | 180,218,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |  |  |  |  |
Increase (decrease) due to foreign currency translation adjustment | 16,900,000 gpor_EquityMethodInvestmentsIncreaseDecreaseDueToForeignCurrencyTranslationAdjustment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember | 12,200,000 gpor_EquityMethodInvestmentsIncreaseDecreaseDueToForeignCurrencyTranslationAdjustment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember | (1,400,000)gpor_EquityMethodInvestmentsIncreaseDecreaseDueToForeignCurrencyTranslationAdjustment / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loans receivable, basis spread on variable rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.00%us-gaap_LoansReceivableBasisSpreadOnVariableRate / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_GrizzlyOilSandsUlcMember |  |  |  |
Bison Drilling And Field Services LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | (213,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember | (3,533,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember | (373,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash calls paid | (17,000,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember | (2,300,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember |  |  |  |  |  |  |  |  |  |  | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember |  |  |  |  |  |  |  |
Equity investments |  | 12,318,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loans receivable, description of variable rate basis | LIBOR |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount loaned during period |  |  |  | 1,600,000 gpor_AmountLoanedDuringPeriod / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Bison Drilling And Field Services LLC [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loans receivable, maximum rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 8.00%us-gaap_DebtInstrumentInterestRateStatedPercentage / us-gaap_RangeAxis = us-gaap_MaximumMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember |  |  |
Muskie Holdings LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | (371,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember | (1,975,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember | (1,031,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash calls paid | (1,000,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember | (2,200,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember |  |  |  |  |  |  |  |  |  |  | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember |  |  |  |  |  |  |  |
Equity investments |  | 7,544,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loan receivable |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 900,000 us-gaap_LoansAndLeasesReceivableRelatedParties / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember |  |
Timber Wolf Terminals LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | (9,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember | 6,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember | (122,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash calls paid |  | (100,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember |  |  |  |  |  |  |  |  |  |  | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember |  |  |  |  |  |  |  |
Equity investments | 1,013,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember | 1,001,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember |  |  |  |  |  |  |  |  |  | 1,013,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember |  |  |  |  |  |  |  |
Payments for equity method investments |  |  | 1,000,000 us-gaap_PaymentsToAcquireEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TimberWolfTerminalsLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Windsor Midstream LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | 477,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember | 1,125,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember | 663,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash calls paid | (2,400,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 22.50%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  | 22.50%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember |  |  |  |  |  |  |  |
Equity investments | 13,505,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember | 10,632,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember |  |  |  |  |  |  |  |  |  | 13,505,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_WindsorMidstreamLlcMember |  |  |  |  |  |  |  |
Stingray Pressure Pumping LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | (2,027,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayPressurePumpingLlcMember | 818,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayPressurePumpingLlcMember | (1,235,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayPressurePumpingLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash calls paid | (2,500,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayPressurePumpingLlcMember | (1,800,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayPressurePumpingLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayPressurePumpingLlcMember |  |  |  |  |  |  |  |  |  |  | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayPressurePumpingLlcMember |  |  |  |  |  |  |  |
Equity investments |  | 19,624,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayPressurePumpingLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Blackhawk Midstream LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | 84,787,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember | (673,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember | (436,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash calls paid |  | (700,000)gpor_EquityMethodInvestmentAmountOfCashCallsBasedOnProportionateOwnershipInterest / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |
Equity investments | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |  |  | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |
Net proceeds received from release of escrow | 7,200,000 us-gaap_EscrowDepositDisbursementsRelatedToPropertyAcquisition1 / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Blackhawk Midstream LLC [Member] | Ohio Gathering Company, LLC and Ohio Condensate Company, LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purchase price |  |  |  |  | 190,000,000 us-gaap_BusinessCombinationConsiderationTransferred1 / us-gaap_BusinessAcquisitionAxis = gpor_OhioGatheringCompanyLLCandOhioCondensateCompanyLLCMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount put in escrow |  |  |  |  | 14,300,000 us-gaap_EscrowDeposit / us-gaap_BusinessAcquisitionAxis = gpor_OhioGatheringCompanyLLCandOhioCondensateCompanyLLCMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Distributions received |  |  |  |  | 84,800,000 us-gaap_EquityMethodInvestmentDividendsOrDistributions / us-gaap_BusinessAcquisitionAxis = gpor_OhioGatheringCompanyLLCandOhioCondensateCompanyLLCMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BlackhawkMidstreamLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Diamondback Energy LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | 79,654,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyLlcMember | 220,129,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyLlcMember | 12,821,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity investments | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyLlcMember | 178,708,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyLlcMember |  |  |  |  |  |  |  |  |  | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyLlcMember |  |  |  |  |  |  | 138,500,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyLlcMember |
Diamondback Energy, Inc [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember | 7.20%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember | 21.40%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember |  |  |  |  |  |  |  |  | 0.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember |  |  |  |  |  |  |  |
Investment (shares) |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 7,914,036 us-gaap_InvestmentOwnedBalanceShares / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember
Sale of stock, Number of shares issued in transaction |  |  |  |  |  | 942,000 us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember | 1,437,500 us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember | 1,000,000 us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember | 2,300,000 us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember | 2,234,536 us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember |  |  |  |  |  |  |  |  |  |
Sale of stock, consideration received |  |  |  |  |  | 60,800,000 us-gaap_SaleOfStockConsiderationReceivedOnTransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember | 197,600,000 us-gaap_SaleOfStockConsiderationReceivedOnTransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember |  | 192,700,000 us-gaap_SaleOfStockConsiderationReceivedOnTransaction / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_DiamondbackEnergyIncMember |  |  |  |  |  |  |  |  |  |  |
Stingray Energy Services LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | 88,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayEnergyServicesLlcMember | 215,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayEnergyServicesLlcMember | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayEnergyServicesLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayEnergyServicesLlcMember |  |  |  |  |  |  |  |  |  |  | 50.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayEnergyServicesLlcMember |  |  |  |  |  |  |  |
Equity investments | 5,718,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayEnergyServicesLlcMember | 3,800,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayEnergyServicesLlcMember |  |  |  |  |  |  |  |  |  | 5,718,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_StingrayEnergyServicesLlcMember |  |  |  |  |  |  |  |
Sturgeon Acquisitions LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | 1,819,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Ownership interest | 25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember |  |  |  |  |  | 25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember |  |  |  | 25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember | 25.00%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember |  |  |  |  |  |  |  |
Equity investments | 22,507,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember |  |  |  |  |  |  |  |  |  | 22,507,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember |  |  |  |  |  |  |  |
Payments for equity method investments |  |  |  |  |  |  |  |  |  |  | 20,700,000 us-gaap_PaymentsToAcquireEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_SturgeonAcquisitionsLLCMember |  |  |  |  |  |  |  |  |
Mammoth Energy Partners LP [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | 201,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember | 0 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |  |  |  |  |  |  |  |  | 84,500,000 us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |  |  |  |  |  |  |  |
Ownership interest | 30.50%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |  |  |  |  |  |  |  |  |  |  | 30.50%us-gaap_EquityMethodInvestmentOwnershipPercentage / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |  |  |  |  |  |  |  |
Equity Method Investments, Fair Value Disclosure | 143,500,000 us-gaap_EquityMethodInvestmentsFairValueDisclosure / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |  |  |  |  |  |  |  |  |  |  | 143,500,000 us-gaap_EquityMethodInvestmentsFairValueDisclosure / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |  |  |  |  |  |  |  |
Equity investments | 143,973,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember | 0 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |  |  |  |  |  |  |  |  |  | 143,973,000 us-gaap_EquityMethodInvestments / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |  |  |  |  |  |  |  |
LIBOR [Member] | Bison Drilling And Field Services LLC [Member] | Minimum [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loans receivable, basis spread on variable rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.28%us-gaap_LoansReceivableBasisSpreadOnVariableRate / us-gaap_RangeAxis = us-gaap_MinimumMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_BisonDrillingAndFieldServicesLlcMember / us-gaap_VariableRateAxis = us-gaap_LondonInterbankOfferedRateLIBORMember |  |  |
Prime Rate [Member] | Muskie Holdings LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loans receivable, basis spread on variable rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2.50%us-gaap_LoansReceivableBasisSpreadOnVariableRate / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MuskieHoldingsLlcMember / us-gaap_VariableRateAxis = us-gaap_PrimeRateMember |  |
Subsequent Event [Member] | Coronado Midstream LLC [Member] | Windsor Midstream LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Property, Plant and Equipment, Estimated Sale Price |  |  |  |  |  |  |  |  |  |  |  |  | 600,000,000 gpor_PropertyPlantandEquipmentEstimatedSalePrice / dei_LegalEntityAxis = gpor_WindsorMidstreamLlcMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_CoronadoMidstreamLLCMember / us-gaap_SubsequentEventTypeAxis = us-gaap_SubsequentEventMember |  |  |  |  |  |  |
Income From Equity Method Investments [Member] | Tatex Thailand III LLC [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
(Income) loss from equity method investments | $ (12,100,000)us-gaap_IncomeLossFromEquityMethodInvestments / us-gaap_IncomeStatementLocationAxis = gpor_IncomeFromEquityMethodInvestmentsMember / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_TatexThailandIiiLlcMember |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition This item represents disclosure of the amount of dividends or other distributions received from unconsolidated subsidiaries, certain corporate joint ventures, and certain noncontrolled corporation; these investments are accounted for under the equity method of accounting. This element excludes distributions that constitute a return of investment, which are classified as investing activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 13 -Article 5 + Details
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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571 + Details
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- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=16385135&loc=d3e33749-111570 + Details
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- Definition The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.10) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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