XML 58 R53.htm IDEA: XBRL DOCUMENT v2.4.1.9
Summary of Significant Accounting Policies Accumulated Other Comprehensive Income (Loss) (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Accumulated other comprehensive (income) loss $ (41.4)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax $ (28.2)us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax  
Other comprehensive income before reclassifications (14.2)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax    
Amounts reclassified from accumulated other comprehensive income (loss) (1.8)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax (3.7)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax (3.0)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax
Amounts reclassified from accumulated other comprehensive income (loss) 1.0us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax    
Net current period other comprehensive income (loss) (13.2)us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent    
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax 0us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax 0.4us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax (1.6)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax 0us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax (0.6)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax 3.6us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax
Amounts Reclassified from Accumulated OCI, Net of Tax and Noncontrolling Interest (1.0)oge_AmountsReclassifiedFromAccumulatedOciNetOfTaxAndNoncontrollingInterest (7.7)oge_AmountsReclassifiedFromAccumulatedOciNetOfTaxAndNoncontrollingInterest  
Components of Net Periodic Benefit Costs to be Recognized in Next Fiscal Year (4.1)oge_ComponentsOfNetPeriodicBenefitCostsToBeRecognizedInNextFiscalYear    
Less: Deconsolidation of Enogex Holdings 0us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation 6.1us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation 0us-gaap_NoncontrollingInterestDecreaseFromDeconsolidation
Pension Plans, Defined Benefit [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Amounts reclassified from accumulated other comprehensive income (loss) (1.7)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 (6.7)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax
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= us-gaap_PensionPlansDefinedBenefitMember		  
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax (3.0)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax
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= us-gaap_PensionPlansDefinedBenefitMember		 [1] (6.1)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 [1]  
Other Comprehensive Income Pension Settlement Adjustment 0.2oge_OtherComprehensiveIncomePensionSettlementAdjustment
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 [1] (4.9)oge_OtherComprehensiveIncomePensionSettlementAdjustment
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= us-gaap_PensionPlansDefinedBenefitMember		 [1]  
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax (2.8)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 (11.0)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTax
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= us-gaap_PensionPlansDefinedBenefitMember		  
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax (1.1)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax
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= us-gaap_PensionPlansDefinedBenefitMember		 (4.3)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax
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= us-gaap_PensionPlansDefinedBenefitMember		  
Amortization of Defined Benefit Pension Items, Amount Reclassified from Accumulated OCI, Noncontrolling Interest 0oge_AmortizationofDefinedBenefitPensionItemsAmountReclassifiedfromAccumulatedOCINoncontrollingInterest
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 (0.1)oge_AmortizationofDefinedBenefitPensionItemsAmountReclassifiedfromAccumulatedOCINoncontrollingInterest
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		  
Amounts Reclassified from Accumulated OCI, Net of Tax and Noncontrolling Interest (1.7)oge_AmountsReclassifiedFromAccumulatedOciNetOfTaxAndNoncontrollingInterest
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember		 (6.6)oge_AmountsReclassifiedFromAccumulatedOciNetOfTaxAndNoncontrollingInterest
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= us-gaap_PensionPlansDefinedBenefitMember		  
Other Postretirement Benefit Plans, Defined Benefit [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Amounts reclassified from accumulated other comprehensive income (loss) 0.9us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember		 (0.2)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax
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Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax (1.4)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember		 [1] (3.3)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossBeforeTax
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Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, before Tax 1.5us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTax
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember		 (0.4)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansBeforeTax
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember		  
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, Tax 0.6us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember		 (0.2)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember		  
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax 2.9us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember		 [1] 2.9us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditBeforeTax
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember		 [1]  
Defined Benefit Plans Income Loss [Member] | Pension Plans, Defined Benefit [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Accumulated other comprehensive income (loss) (36.8)us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
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= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		 (27.4)us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
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= us-gaap_PensionPlansDefinedBenefitMember
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Other comprehensive income before reclassifications (11.1)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax
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= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		    
Amounts reclassified from accumulated other comprehensive income (loss) 1.7us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax
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Net current period other comprehensive income (loss) (9.4)us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
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= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		    
Components of Net Periodic Benefit Costs to be Recognized in Next Fiscal Year (5.1)oge_ComponentsOfNetPeriodicBenefitCostsToBeRecognizedInNextFiscalYear
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= us-gaap_PensionPlansDefinedBenefitMember
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= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		    
Defined Benefit Plans Income Loss [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Accumulated other comprehensive income (loss) (8.0)us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
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/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		 (5.8)us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
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= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		  
Other comprehensive income before reclassifications (3.1)us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
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/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		    
Amounts reclassified from accumulated other comprehensive income (loss) 0.9us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
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/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		    
Net current period other comprehensive income (loss) (2.2)us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		    
Components of Net Periodic Benefit Costs to be Recognized in Next Fiscal Year (1.9)oge_ComponentsOfNetPeriodicBenefitCostsToBeRecognizedInNextFiscalYear
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= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLossMember		    
Defined Benefit Plan Prior Service Cost [Member] | Pension Plans, Defined Benefit [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Accumulated other comprehensive income (loss) 0.1us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
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= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		 0.1us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
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= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		  
Other comprehensive income before reclassifications 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		    
Amounts reclassified from accumulated other comprehensive income (loss) 0us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		    
Net current period other comprehensive income (loss) 0us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
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= us-gaap_PensionPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		    
Defined Benefit Plan Prior Service Cost [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Accumulated other comprehensive income (loss) 3.3us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
/ us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis
= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
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= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		 5.1us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
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Other comprehensive income before reclassifications 0us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
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/ us-gaap_StatementEquityComponentsAxis
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Amounts reclassified from accumulated other comprehensive income (loss) (1.8)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansNetOfTax
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/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		    
Net current period other comprehensive income (loss) (1.8)us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
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= us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember
/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		    
Components of Net Periodic Benefit Costs to be Recognized in Next Fiscal Year 2.9oge_ComponentsOfNetPeriodicBenefitCostsToBeRecognizedInNextFiscalYear
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/ us-gaap_StatementEquityComponentsAxis
= us-gaap_AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCreditMember		    
Interest Rate Swap [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Accumulated other comprehensive income (loss) 0us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax
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= us-gaap_InterestRateSwapMember		 (0.2)us-gaap_AccumulatedOtherComprehensiveIncomeLossCumulativeChangesInNetGainLossFromCashFlowHedgesEffectNetOfTax
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Other comprehensive income before reclassifications 0us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax
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Amounts reclassified from accumulated other comprehensive income (loss) 0.2us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet
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= us-gaap_InterestRateSwapMember		    
Net current period other comprehensive income (loss) 0.2us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
/ us-gaap_StatementEquityComponentsAxis
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Commodity Contract [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax 0us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax
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Derivative [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax (0.3)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax
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Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax (0.1)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax
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Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax (0.2)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax
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Interest Expense [Member] | Interest Rate Swap [Member]      
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]      
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax $ (0.3)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax
/ us-gaap_DerivativeByNatureAxis
= us-gaap_InterestRateSwapMember
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= us-gaap_InterestExpenseMember		 $ (0.4)us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesBeforeTax
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/ us-gaap_IncomeStatementLocationAxis
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[1] These accumulated other comprehensive income (loss) components are included in the computation of net periodic benefit cost (see Note 12 for additional information).
[2] Includes $0.1 million of pension curtailment charges.