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Income Taxes Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Details) (USD $)
In Thousands, unless otherwise specified |
Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Income Tax Disclosure [Abstract] | |||
| Net operating loss carryforward | $ 1,091us-gaap_DeferredTaxAssetsOperatingLossCarryforwards | $ 1,462us-gaap_DeferredTaxAssetsOperatingLossCarryforwards | $ 1,513us-gaap_DeferredTaxAssetsOperatingLossCarryforwards |
| FASB ASC 718 compensation expense | 1,562us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost | 634us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost | 762us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost |
| AMT credit | 24,053us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax | 7,968us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax | 1,643us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsAlternativeMinimumTax |
| Charitable contributions carryover | 150us-gaap_DeferredTaxAssetsCharitableContributionCarryforwards | 25us-gaap_DeferredTaxAssetsCharitableContributionCarryforwards | 5us-gaap_DeferredTaxAssetsCharitableContributionCarryforwards |
| Unrealized loss on hedging activities | 0us-gaap_DeferredTaxAssetsHedgingTransactions | 8,540us-gaap_DeferredTaxAssetsHedgingTransactions | 3,836us-gaap_DeferredTaxAssetsHedgingTransactions |
| Foreign tax credit carryforwards | 2,074us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign | 2,074us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign | 2,074us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign |
| Accrued liabilities | 1,260us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities | 0us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities | 0us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities |
| State net operating loss carryover | 2,627us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal | 4,408us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal | 4,315us-gaap_DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal |
| Total deferred tax assets | 32,817us-gaap_DeferredTaxAssetsGross | 25,111us-gaap_DeferredTaxAssetsGross | 14,148us-gaap_DeferredTaxAssetsGross |
| Valuation allowance for deferred tax assets | (3,145)us-gaap_DeferredTaxAssetsValuationAllowance | (4,743)us-gaap_DeferredTaxAssetsValuationAllowance | (4,629)us-gaap_DeferredTaxAssetsValuationAllowance |
| Deferred tax assets, net of valuation allowance | 29,672us-gaap_DeferredTaxAssetsNet | 20,368us-gaap_DeferredTaxAssetsNet | 9,519us-gaap_DeferredTaxAssetsNet |
| Oil and gas property basis difference | 183,767gpor_DeferredTaxLiabilityOilAndGasPropertyBasisDifference | 72,173gpor_DeferredTaxLiabilityOilAndGasPropertyBasisDifference | 15,049gpor_DeferredTaxLiabilityOilAndGasPropertyBasisDifference |
| Investment in pass through entities | 38,315us-gaap_DeferredTaxLiabilitiesInvestments | 8,799us-gaap_DeferredTaxLiabilitiesInvestments | 3,618us-gaap_DeferredTaxLiabilitiesInvestments |
| Non-oil and gas property basis difference | 849gpor_DeferredTaxLiabilitiesNonoilAndGasPropertyBasisDifference | 249gpor_DeferredTaxLiabilitiesNonoilAndGasPropertyBasisDifference | 227gpor_DeferredTaxLiabilitiesNonoilAndGasPropertyBasisDifference |
| Investment in nonconsolidated affiliates | 0us-gaap_DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates | 46,495us-gaap_DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates | 9,232us-gaap_DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates |
| Unrealized gain on hedging activities | 37,006us-gaap_DeferredTaxLiabilitiesDerivatives | 0us-gaap_DeferredTaxLiabilitiesDerivatives | 0us-gaap_DeferredTaxLiabilitiesDerivatives |
| Total deferred tax liabilities | 259,937us-gaap_DeferredTaxLiabilities | 127,716us-gaap_DeferredTaxLiabilities | 28,126us-gaap_DeferredTaxLiabilities |
| Net deferred tax liability | $ (230,265)us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent | $ (107,348)us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent | $ (18,607)us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent |
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- Definition
Deferred Tax Liabilities, Non-oil And Gas Property Basis Difference No definition available.
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- Definition
The tax effect as of the balance sheet date of the estimated future tax effects attributable to the difference between the tax basis of oil and gas assets and the basis of oil and gas assets computed in accordance with generally accepted accounting principles. The difference in basis, attributable to different capitalization of costs, depreciation, or amortization methodologies, will impact future taxable income when such basis difference is realized. No definition available.
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible charitable contribution carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from hedging transactions. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences expected to be realized or consumed after one year (or the normal operating cycle, if longer). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign tax credit carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from accrued liabilities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of deferred tax liability attributable to taxable temporary differences net of deferred tax asset attributable to deductible temporary differences and carryforwards after valuation allowances. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of deferred tax liability attributable to taxable temporary differences from derivatives. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of deferred tax liability attributable to taxable temporary differences from investments in unconsolidated subsidiaries and investments in other affiliates which are not controlled nor consolidated. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount of deferred tax liability attributable to taxable temporary differences from investments (excludes investments in subsidiaries and equity method investments). No definition available.
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- Details
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