XML 81 R54.htm IDEA: XBRL DOCUMENT
v3.19.3

DERIVATIVE INSTRUMENTS (Schedule of Derivative Instruments) (Details) |  | 9 Months Ended
--- | --- | ---
Sep. 30, 2017 MMBTU | Sep. 30, 2019 MMBTU $ / bbl $ / MMBTU bbl
NYMEX Henry Hub Swap - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 1,380,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 2.81
NYMEX Henry Hub Swap - 2019 | Short | Call Option |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 30,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 3.10
NYMEX Henry Hub Swap - 2020 |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 519,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 2.88
NYMEX Henry Hub Swap - 2022 | Short | Call Option |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 628,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 2.90
NYMEX Henry Hub Swap - 2023 | Short | Call Option |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU | 628,000 |
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 2.90
NYMEX WTI Swap - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 6,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 60.81
NYMEX WTI Swap - 2020 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 6,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 59.82
Mont Belvieu C2 - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 1,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 18.48
Mont Belvieu C3 Swap - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 4,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 29.02
Mont Belvieu C5 Swap - 2019 |  |
Derivative [Line Items] |  |
Daily Volume (Bbls/day) | bbl |  | 1,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl |  | 53.71
Transco Zone 4 - 2019 | Long |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 60,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 0.05
Transco Zone 4 - 2020 | Long |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 60,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 0.05
Fixed Spread - 2020 | Long |  |
Derivative [Line Items] |  |
Daily Volume (MMBtu/day) | MMBTU |  | 10,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU |  | 0.54

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nominal energy measure used to calculate payments on a derivative instrument. + References No definition available. + Details
Name: | us-gaap_DerivativeNonmonetaryNotionalAmountEnergyMeasure
Namespace Prefix: | us-gaap_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | duration

X
- Definition Nominal volume used to calculate payments on a derivative instrument. + References No definition available. + Details
Name: | us-gaap_DerivativeNonmonetaryNotionalAmountVolume
Namespace Prefix: | us-gaap_
Data Type: | num:volumeItemType
Balance Type: | na
Period Type: | duration

X
- Definition Average fixed price related to the group of price risk swap derivatives. + References No definition available. + Details
Name: | us-gaap_DerivativeSwapTypeAverageFixedPrice
Namespace Prefix: | us-gaap_
Data Type: | srt-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_NYMEXHenryHubSwap2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_OptionIndexedToIssuersEquityEquityAxis=us-gaap_CallOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_NYMEXHenryHubSwap2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_NYMEXHenryHubSwap2022Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_NYMEXHenryHubSwap2023Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_NYMEXWTISwap2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_NYMEXWTISwap2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_MontBelvieuC22019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_MontBelvieuC3Swap2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_MontBelvieuC5Swap2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_TranscoZone42019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PositionAxis=us-gaap_LongMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_TranscoZone42020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=gpor_FixedSpread2020Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |