XML 107 R89.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Supplemental Information on Oil and Gas Exploration and Production Activities (Unaudited) Supplemental Information on Oil and Gas Exploration and Production Activities (Unaudited) - Narrative (Details) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2016 USD ($) MMcfe well $ / MMBTU $ / bbl | Dec. 31, 2015 MMcfe $ / MMBTU $ / bbl | Dec. 31, 2014 MMcfe $ / MMBTU $ / bbl
Reserve Quantities [Line Items] |  |  |
Future development costs estimated to be spent year one | $ | $ 401.5 |  |
Future development costs estimated to be spent year two | $ | 331.4 |  |
Future development costs estimated to be spent year three | $ | $ 192.7 |  |
Paloma and AEU |  |  |
Reserve Quantities [Line Items] |  |  |
Proved developed and undeveloped reserve, purchase of mineral in place | 371,663 |  |
Rhino Exploration, LLC, Utica Shale Properties |  |  |
Reserve Quantities [Line Items] |  |  |
Proved developed and undeveloped reserve, purchase of mineral in place |  |  | 12,019
Oil derivatives |  |  |
Reserve Quantities [Line Items] |  |  |
Price per unit (usd per barrel or MMbtu) | $ / bbl | 42.75 | 50.28 | 94.99
Natural gas, per MMbtu |  |  |
Reserve Quantities [Line Items] |  |  |
Price per unit (usd per barrel or MMbtu) | $ / MMBTU | 2.48 | 2.59 | 4.35
Natural gas liquids |  |  |
Reserve Quantities [Line Items] |  |  |
Price per unit (usd per barrel or MMbtu) | $ / bbl | 9.91 | 13.21 | 44.84
Utica Shale |  |  |
Reserve Quantities [Line Items] |  |  |
Increase (decrease) in reserve during the period | 1,100,000 | 1,044,500 | 786,347
Planned unit development | well | 34 |  |
Proved developed and undeveloped reserve, production increase, percentage (Energy) | 14.50% |  |
Utica Shale | Lower commodity prices |  |  |
Reserve Quantities [Line Items] |  |  |
Proved developed and undeveloped reserve, revision of previous estimate | (227,900) |  |
Planned unit development loss | well | 35 |  |
Development Wells Drilled, Productive and Non-Productive | well | 67 |  |
Utica Shale | Rescheduled drilling |  |  |
Reserve Quantities [Line Items] |  |  |
Proved developed and undeveloped reserve, revision of previous estimate | 17,400 |  |
Planned unit development | well | 4 |  |
Proved undeveloped reserves, postponement of drilling period | 5 years |  |
Utica Shale | Improved performance |  |  |
Reserve Quantities [Line Items] |  |  |
Proved developed and undeveloped reserve, revision of previous estimate | 26,700 |  |
Southern Louisiana and Utica Fields |  |  |
Reserve Quantities [Line Items] |  |  |
Proved developed and undeveloped reserve, revision of previous estimate | (444,314) |  | (15,837)
Proved undeveloped reserves, postponement of drilling period |  |  | 5 years
Investment in Grizzly Oil Sands ULC |  |  |
Reserve Quantities [Line Items] |  |  |
Equity investment ownership interest | 24.9999% |  |

X
- Definition Development Wells Drilled, Productive and Non-Productive + References No definition available. + Details
Name: | gpor_DevelopmentWellsDrilledProductiveandNonProductive
Namespace Prefix: | gpor_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Future development costs estimated to be spent in year one + References No definition available. + Details
Name: | gpor_FutureDevelopmentCostsEstimatedToBeSpentInYearOne
Namespace Prefix: | gpor_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Future Development Costs Estimated To Be Spent In Year Three + References No definition available. + Details
Name: | gpor_FutureDevelopmentCostsEstimatedToBeSpentInYearThree
Namespace Prefix: | gpor_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Future Development Costs Estimated To Be Spent In Year Two + References No definition available. + Details
Name: | gpor_FutureDevelopmentCostsEstimatedToBeSpentInYearTwo
Namespace Prefix: | gpor_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Proved Developed and Undeveloped Reserve, Production Increase, Percentage (Energy) + References No definition available. + Details
Name: | gpor_ProvedDevelopedandUndevelopedReserveProductionIncreasePercentageEnergy
Namespace Prefix: | gpor_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Proved Undeveloped Reserves, Postponement of Drilling Period + References No definition available. + Details
Name: | gpor_ProvedUndevelopedReservesPostponementofDrillingPeriod
Namespace Prefix: | gpor_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The revenues derived from sales of oil or gas in each geographic area during the reporting period divided by the number of barrels of oil produced or thousands of cubic feet of gas produced. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1204 -Paragraph (b) -Subparagraph (1) + Details
Name: | us-gaap_AverageSalesPrices
Namespace Prefix: | us-gaap_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of nonproductive development wells (dry wells) drilled in the geographic area. A dry well (hole) is a well found to be incapable of producing either oil or gas in sufficient quantities to justify completion as an oil or gas well. The number of wells drilled refers to the number of wells (holes) completed at any time during the fiscal years, regardless when drilling was initiated. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1205 -Paragraph (a) -Subparagraph (2) + Details
Name: | us-gaap_DevelopmentWellsDrilledNetNonproductive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of productive developmental wells drilled in the geographic area. A productive well is a well that is not a dry well. The number of wells drilled refers to the number of wells (holes) completed at any time during the fiscal years, regardless when drilling was initiated. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1205 -Paragraph (a) -Subparagraph (2) + Details
Name: | us-gaap_DevelopmentWellsDrilledNetProductive
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- 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=66011266&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Energy measure of increase in quantity of proved reserve of oil and gas resulting from the extension of the proved acreage of previously discovered reservoir or discovery of new field with proved reserve or of new reservoir of proved reserve in old field, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
Name: | us-gaap_ProvedDevelopedAndUndevelopedReserveExtensionAndDiscoveryEnergy
Namespace Prefix: | us-gaap_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | duration

X
- Definition Energy measure of increase in quantity of proved reserve of oil and gas resulting from purchase of mineral in place, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
Name: | us-gaap_ProvedDevelopedAndUndevelopedReservePurchaseOfMineralInPlaceEnergy
Namespace Prefix: | us-gaap_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | duration

X
- Definition Energy measure of increase (decrease) in quantity of proved reserve of oil and gas related to revision of a previous estimate resulting from new information, except for an increase in proved acreage, or change in economic factors, stated in a unit of energy. For example, but not limited to, barrel of oil equivalents (BOE) or one thousand cubic feet of natural gas equivalent (Mcfe). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=68064819&loc=d3e61831-109447 + Details
Name: | us-gaap_ProvedDevelopedAndUndevelopedReserveRevisionOfPreviousEstimateEnergy
Namespace Prefix: | us-gaap_
Data Type: | num:energyItemType
Balance Type: | na
Period Type: | duration

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_ReserveQuantitiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=gpor_PalomaandAEUMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=gpor_RhinoExplorationLLCUticaShalePropertiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ReserveQuantitiesByTypeOfReserveAxis=us-gaap_OilReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ReserveQuantitiesByTypeOfReserveAxis=us-gaap_NaturalGasPerThousandCubicFeetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ReserveQuantitiesByTypeOfReserveAxis=us-gaap_NaturalGasLiquidsReservesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=gpor_UticaShaleMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | gpor_ProductivityRevisionsAxis=gpor_LowerCommodityPricesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | gpor_ProductivityRevisionsAxis=gpor_RescheduledDrillingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | gpor_ProductivityRevisionsAxis=gpor_ImprovedPerformanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=gpor_SouthernLouisianaandUticaFieldsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=gpor_GrizzlyOilSandsUlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |