Fair Value of Financial Instruments (Details) (USD $)
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Dec. 31, 2014
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Aug. 18, 2014
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Dec. 21, 2012
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Oct. 17, 2012
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Debt Instrument [Line Items] | ||||
Unamortized discount | $ 2,800,000us-gaap_DebtInstrumentUnamortizedDiscount | |||
Fair value of notes | 587,600,000us-gaap_DebtInstrumentFairValue | |||
Senior Notes [Member] | ||||
Debt Instrument [Line Items] | ||||
Carrying value of debt |
614,700,000us-gaap_DebtLongtermAndShorttermCombinedAmount / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |
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Unamortized discount |
3,700,000us-gaap_DebtInstrumentUnamortizedDiscount / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |
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Unamortized premium |
18,000,000us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |
500,000us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_LongtermDebtTypeAxis = us-gaap_SeniorNotesMember |
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December Notes [Member] | ||||
Debt Instrument [Line Items] | ||||
Unamortized premium |
400,000us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_DebtInstrumentAxis = gpor_DecemberNotesMember |
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August Notes [Member] | ||||
Debt Instrument [Line Items] | ||||
Unamortized premium |
17,100,000us-gaap_DebtInstrumentUnamortizedPremium / us-gaap_DebtInstrumentAxis = gpor_AugustNotesMember |
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Mammoth Energy Partners LP [Member] | ||||
Debt Instrument [Line Items] | ||||
Equity Method Investments, Fair Value Disclosure |
$ 143,500,000us-gaap_EquityMethodInvestmentsFairValueDisclosure / us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis = gpor_MammothEnergyPartnersLPMember |
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- Definition
Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of debt discount that was originally recognized at the issuance of the instrument that has yet to be amortized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of debt premium that was originally recognized at the issuance of the instrument that has yet to be amortized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Represents the aggregate of total long-term debt, including current maturities and short-term debt. No definition available.
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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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