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Acquisitions (Details) (USD $) | 3 Months Ended | 0 Months Ended |
--- | --- | --- | ---
Mar. 31, 2015 | Mar. 31, 2014 | Mar. 20, 2014 | Feb. 28, 2014 acre
Business Acquisition [Line Items] |  |  |  |
Net revenues | $ 176,317,000 us-gaap_Revenues | $ 118,029,000 us-gaap_Revenues |  |
Lease operating expenses | 16,980,000 us-gaap_LeaseOperatingExpense | 11,629,000 us-gaap_LeaseOperatingExpense |  |
Utica Shale [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Gas and oil acreage, undeveloped, net |  |  |  | 8,000 us-gaap_GasAndOilAreaUndevelopedNet / us-gaap_BusinessAcquisitionAxis = gpor_UticaShaleMember
Purchase price |  |  | 182,000,000 us-gaap_BusinessCombinationConsiderationTransferred1 / us-gaap_BusinessAcquisitionAxis = gpor_UticaShaleMember |
Cash, net of purchase price adjustments |  |  | 179,527,000 gpor_PaymenttoAcquireOilandGasPropertyandEquipmentNet / us-gaap_BusinessAcquisitionAxis = gpor_UticaShaleMember |
Fair value of net identifiable assets acquired |  |  | 179,527,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment / us-gaap_BusinessAcquisitionAxis = gpor_UticaShaleMember |
Utica Shale [Member] | Proved Properties [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair value of net identifiable assets acquired |  |  | 31,961,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment / us-gaap_BusinessAcquisitionAxis = gpor_UticaShaleMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = gpor_ProvedPropertiesMember |
Utica Shale [Member] | Unproved Properties [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair value of net identifiable assets acquired |  |  | 6,263,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment / us-gaap_BusinessAcquisitionAxis = gpor_UticaShaleMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = gpor_UnprovedPropertiesMember |
Utica Shale [Member] | Unevaluated Properties [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Fair value of net identifiable assets acquired |  |  | $ 141,303,000 us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment / us-gaap_BusinessAcquisitionAxis = gpor_UticaShaleMember / us-gaap_PropertyPlantAndEquipmentByTypeAxis = gpor_UnevaluatedPropertiesMember |

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- Definition Payment to Acquire Oil and Gas Property and Equipment, Net + References No definition available. + Details
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- Definition Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 30 -Section 30 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477 + Details
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- Definition The amount of property, plant, and equipment recognized as of the acquisition date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=56956791&loc=d3e4845-128472 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 805 -SubTopic 10 -Section 55 -Paragraph 37 -URI http://asc.fasb.org/extlink&oid=35744172&loc=d3e2207-128464 + Details
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- Definition Fractional interest owned based on working interests or other economic arrangements of lease area on which wells have not been drilled or completed to a point that would permit the production of commercial quantities of oil and gas regardless of whether or not such area contains proved reserves. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-K (SK) -Number 229 -Section 1208 -Paragraph (b) + Details
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- Definition Amount of lease operating expense related to property used in oil and gas production. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 840 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6453985&loc=d3e41499-112717 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 10 -Paragraph a -Subparagraph 17 -Article 4 + Details
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- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
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