XML 61 R49.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

EQUITY INVESMENTS (Narrative) (Details) $ / shares in Units, a in Thousands | 3 Months Ended | 9 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2019 USD ($) shares | Sep. 30, 2018 USD ($) | Sep. 30, 2019 USD ($) a $ / shares shares | Sep. 30, 2018 USD ($) | May 31, 2018 | May 01, 2018
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Loss (income) from equity method investments, net | $ 43,082,000 | $ (12,858,000) | $ 164,391,000 | $ (35,282,000) |  |
Distributions from equity method investments |  |  | 1,945,000 | 446,000 |  |
Mammoth Energy Services LP |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Equity method investment, impairment | $ 35,500,000 |  | 160,800,000 |  |  |
Distributions from equity method investments |  |  | $ 2,500,000 |  |  |
Equity method investment, ownership interest (in shares) | shares | 9,829,548 |  | 9,829,548 |  |  |
Share dividend (in usd per share) | $ / shares |  |  | $ 0.125 |  |  |
Approximate fair value, quoted market price | $ 24,400,000 |  | $ 24,400,000 |  |  |
Tatex Thailand II, LLC |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Loss (income) from equity method investments, net | $ 0 | (137,000) | $ (2,085,000) | (241,000) |  |
Equity method investment, ownership interest, percent | 23.50% |  | 23.50% |  |  |
Grizzly Oil Sands ULC |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Gas and oil area, reserve (in acres) | a |  |  | 830 |  |  |
Loss (income) from equity method investments, net | $ 41,000 | 275,000 | $ 380,000 | 833,000 |  |
Equity method investment, ownership interest, percent | 24.9999% |  | 24.9999% |  |  |
Equity method investment, impairment |  |  | $ 0 | 0 |  |
Equity method investment, amount of cash calls, based on proportionate ownership interest |  |  | 400,000 |  |  |
Equity method investments, increase (decrease) due to foreign currency translation adjustment | $ (2,000,000.0) | 2,900,000 | 5,200,000 | (5,700,000) |  |
Windsor Midstream LLC |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Loss (income) from equity method investments, net | $ 0 | 0 | $ 0 | (9,000) |  |
Equity method investment, ownership interest, percent | 22.50% |  | 22.50% |  |  |
Distributions from equity method investments |  |  | $ 0 |  |  |
Mammoth Energy Services LP |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Equity method investments, increase (decrease) due to foreign currency translation adjustment | $ (100,000) | 100,000 | 100,000 | (200,000) |  |
Strike Force Midstream LLC |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Loss (income) from equity method investments, net | $ 0 | $ 0 | $ 0 | $ (693,000) |  |
Equity method investment, ownership interest, percent | 0.00% |  | 0.00% |  |  | 25.00%
Phu Horm Field | Apico Llc |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Gas and oil area, reserve (in acres) | a |  |  | 108 |  |  |
Apico Llc | Tatex Thailand II, LLC |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Ownership percentage | 8.50% |  | 8.50% |  |  |
Apico Llc | Tatex Thailand II, LLC |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Loss (income) from equity method investments, net |  |  | $ 1,900,000 |  |  |
Investee | Mammoth Energy Services LP |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Equity method investment, ownership interest, percent | 21.80% |  | 21.80% |  |  |
Investee | Strike Force Midstream LLC |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Equity method investment, ownership interest, percent |  |  |  |  | 25.00% |

X
- Definition Cost Method Investment, Ownership Percentage + References No definition available. + Details
Name: | gpor_CostMethodInvestmentOwnershipPercentage
Namespace Prefix: | gpor_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Equity Method Investment, Amount of Cash Calls, Based on Proportionate Ownership Interest + References No definition available. + Details
Name: | gpor_EquityMethodInvestmentAmountofCashCallsBasedonProportionateOwnershipInterest
Namespace Prefix: | gpor_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Equity Method Investment, Ownership, Shares + References No definition available. + Details
Name: | gpor_EquityMethodInvestmentOwnershipShares
Namespace Prefix: | gpor_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Change in the balance sheet adjustment that results from the process of translating subsidiary financial statements and foreign equity investments into functional currency of the reporting entity for the period being reported, net of tax. + References No definition available. + Details
Name: | gpor_EquityMethodInvestmentsIncreaseDecreaseDueToForeignCurrencyTranslationAdjustment
Namespace Prefix: | gpor_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Gas And Oil Area, Reserve + References No definition available. + Details
Name: | gpor_GasAndOilAreaReserve
Namespace Prefix: | gpor_
Data Type: | num:areaItemType
Balance Type: | na
Period Type: | duration

X
- Definition This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 35 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=118954474&loc=d3e32787-111569 + Details
Name: | us-gaap_EquityMethodInvestmentOtherThanTemporaryImpairment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition This item represents the aggregate value of each identified investment accounted for under the equity method of accounting based on the quoted market price for those investments in common stock for which a quoted market price is available. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentQuotedMarketValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of income (loss) for proportionate share of equity method investee's income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03(12)) -URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(10)) -URI http://asc.fasb.org/extlink&oid=116637232&loc=SL114874131-224263 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04(13)(f)) -URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 22 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 + Details
Name: | us-gaap_IncomeLossFromEquityMethodInvestments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Per share or unit amount of distribution to shareholders. Includes, but is not limited to, dividend and capital gain. Excludes distribution for tax return of capital. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 205 -Section 50 -Paragraph 7 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=25866437&loc=d3e10246-115837 + Details
Name: | us-gaap_InvestmentCompanyDistributionToShareholdersPerShare
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of distribution received from equity method investee for return of investment, classified as investing activities. Excludes distribution for return on investment, classified as operating activities. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 21D -URI http://asc.fasb.org/extlink&oid=118932676&loc=SL94080555-108585 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 12 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585 + Details
Name: | us-gaap_ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_ScheduleOfEquityMethodInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=gpor_MammothEnergyServicesLPMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=gpor_TatexThailandIiLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=gpor_WindsorMidstreamLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=gpor_MammothEnergyServicesLPMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=gpor_StrikeForceMidstreamLLCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RealEstateAndAccumulatedDepreciationDescriptionOfPropertyAxis=gpor_PhuHormFieldMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=gpor_ApicoLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_OwnershipAxis=gpor_ApicoLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=gpor_TatexThailandIiLlcMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_InvesteeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |