XML 49 R38.htm IDEA: XBRL DOCUMENT
v3.20.2

BASIS OF PRESENTATION, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND LIQUIDITY, MANAGEMENT'S PLANS AND GOING CONCERN (Narrative) (Details) - USD ($) |  |  | 9 Months Ended |  |
--- | --- | --- | --- | --- | ---
Nov. 02, 2020 | Oct. 15, 2020 | Sep. 30, 2020 | Oct. 08, 2020 | Dec. 31, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |  |  |  |
Percentage decrease in capital spending (more than) |  |  | 50.00% |  |
Unsecured notes repurchased |  |  |  |  | $ 200,000,000
Long-term debt |  |  | $ 2,100,000,000 |  |
Revolving Credit Agreement | Revolving Credit Agreement |  |  |  |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |  |  |  |
Borrowing base |  |  | 700,000,000 |  |
Unsecured Debt |  |  |  |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |  |  |  |
Unsecured notes repurchased |  |  | $ 73,300,000 |  |
Senior Notes | 6.000% senior unsecured notes due 2024 |  |  |  |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |  |  |  |
Stated interest rate, percent |  |  | 6.00% |  |
Senior Notes | 6.625% senior unsecured notes due 2023 |  |  |  |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |  |  |  |
Stated interest rate, percent |  |  | 6.625% |  |
Subsequent Event | Revolving Credit Agreement | Revolving Credit Agreement |  |  |  |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |  |  |  |
Borrowing base |  |  |  | $ 580,000,000 |
Subsequent Event | Senior Notes | 6.000% senior unsecured notes due 2024 |  |  |  |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |  |  |  |
Debt instrument, interest |  | $ 17,400,000 |  |  |
Stated interest rate, percent |  | 6.00% |  |  |
Subsequent Event | Senior Notes | 6.625% senior unsecured notes due 2023 |  |  |  |  |
Error Corrections and Prior Period Adjustments Restatement [Line Items] |  |  |  |  |
Debt instrument, interest | $ 10,800,000 |  |  |  |
Stated interest rate, percent | 6.625% |  |  |  |

X
- Definition Decrease In Capital Spending, Percentage + References No definition available. + Details
Name: | gpor_DecreaseInCapitalSpendingPercentage
Namespace Prefix: | gpor_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of the required periodic payments applied to interest. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentPeriodicPaymentInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value amount of debt instrument that was repurchased. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentRepurchaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b),22(b)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gpor_AmendedAndRestatedCreditAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_LineOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_UnsecuredDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gpor_A6.000SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=gpor_A6.625SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |