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Hedging Activities (Narrative) (Details) (USD $)
In Millions, unless otherwise specified |
12 Months Ended | ||
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Dec. 31, 2014
financial_institution
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Dec. 31, 2013
financial_institution
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Dec. 31, 2012
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| General Discussion of Derivative Instruments and Hedging Activities [Abstract] | |||
| Number of financial institutions | 4gpor_NumberOfFinancialInstitutions | 4gpor_NumberOfFinancialInstitutions | |
| Gain on fair value hedge ineffectiveness, net | $ 121.1us-gaap_GainLossOnFairValueHedgeIneffectivenessNet | $ (18.2)us-gaap_GainLossOnFairValueHedgeIneffectivenessNet | $ (0.1)us-gaap_GainLossOnFairValueHedgeIneffectivenessNet |
| Gain on fair value hedge ineffectiveness | (9.1)us-gaap_LossOnFairValueHedgeIneffectiveness | ||
| Loss related to amortization of OCI from hedging activity | $ (9.1)us-gaap_OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax | ||
| Production delivered under fixed price swaps, percentage | 62.00%gpor_ProductionDeliveredUnderFixedPriceSwapsPercentage | ||
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- Definition
Number Of Financial Institutions No definition available.
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- Definition
Production Delivered Under Fixed Price Swaps, Percentage No definition available.
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- Definition
Amount of gain (loss)recognized in the income statement from the hedging ineffectiveness of a fair value hedge. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
Amount of recognized loss from the hedging ineffectiveness of a fair value hedge. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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