2.2.0.7 true Investments (Details 6) (USD $) 4045 - Disclosure - Investments (Details 6) true false In Millions false false 1 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 USD true false false false ceg_RSBBondCoLLCMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_RSBBondCoLLCMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 3 USD true false false false ceg_RSBBondCoLLCMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_RSBBondCoLLCMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 4 USD true false false false ceg_RSBBondCoLLCMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_RSBBondCoLLCMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 5 true false false false ceg_RetailGasCustomerSupplyOperationMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_RetailGasCustomerSupplyOperationMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis explicitMember Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 false 6 USD true false false false ceg_PowerProjectsAndFuelSupplyEntitiesMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_PowerProjectsAndFuelSupplyEntitiesMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 $ false 7 USD true false false false ceg_RetailGasSupplyContractMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_RetailGasSupplyContractMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis explicitMember false false us-gaap_FinancialStandbyLetterOfCreditMember us-gaap_GuaranteeObligationsByNatureAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_FinancialStandbyLetterOfCreditMember us-gaap_GuaranteeObligationsByNatureAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 8 USD true false false false ceg_RetailGasSupplyContractMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_RetailGasSupplyContractMember us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis explicitMember false false us-gaap_GuaranteeTypeOtherMember us-gaap_GuaranteeObligationsByNatureAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_GuaranteeTypeOtherMember us-gaap_GuaranteeObligationsByNatureAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ 4 Variable Interest Entity 2 us-gaap_VariableInterestEntityLineItems us-gaap true na duration No definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false xbrli:stringItemType string 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. false 5 Our maximum exposure to loss 3 ceg_VariableInterestEntityEntityMaximumLossExposureAmount ceg false credit instant The amount of the entity's maximum exposure to loss as a result of its involvement with the Variable Interest Entity (VIE). false false false false false false false false false false false terselabel false 1 true true false false 99300000 99.3 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false xbrli:monetaryItemType monetary The amount of the entity's maximum exposure to loss as a result of its involvement with the Variable Interest Entity (VIE). No authoritative reference available. false 6 Debt guarantee and working capital funding 3 ceg_AmountOfDebtGuaranteeAndWorkingCapitalFunding ceg false credit instant The amount of the debt guarantee and working capital funds, as of the balance sheet date. false false false false false false false false false false false terselabel false 1 false false false false 0 0     false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false true false false 2000000 2.0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false xbrli:monetaryItemType monetary The amount of the debt guarantee and working capital funds, as of the balance sheet date. No authoritative reference available. false 7 Obligations under gas supply agreement 3 ceg_VariableInterestEntityFinancialOrOtherSupportAmount ceg false credit instant This item represents the amount of financial or other support the reporting entity has provided (explicitly or implicitly) to... false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false true false false 65000000 65.0 true false false 8 false true false false 100000000 100.0 true false false xbrli:monetaryItemType monetary This item represents the amount of financial or other support the reporting entity has provided (explicitly or implicitly) to the Variable Interest Entity (VIE) that it was not previously contractually required to provide or that the reporting entity intends to provide, including, for example, situations in which the reporting entity assisted the VIE in obtaining another type of support. No authoritative reference available. false 8 Number of consolidated variable interest entities 3 ceg_NumberOfVariableInterestEntities ceg false na instant The number of variable interest entities consolidated in the reporting entity's consolidated financial statements. false false false false false false false false false false false terselabel false 1 false true false false 3 3 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false xbrli:integerItemType integer The number of variable interest entities consolidated in the reporting entity's consolidated financial statements. No authoritative reference available. false 9 Remittance by BGE of payments received from customers for rate stabilization 3 ceg_AmountRemittedToVariableInterestEntitiesOnRateStabilizationBonds ceg false debit duration The amount remitted to variable interest entities for rate stabilization bonds. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false true false false 85800000 85.8 true false false 3 false true false false 87200000 87.2 true false false 4 false true false false 38400000 38.4 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false xbrli:monetaryItemType monetary The amount remitted to variable interest entities for rate stabilization bonds. No authoritative reference available. false 10 New variable interest entities formed 3 ceg_NumberOfNewVariableInterestEntitiesFormedDuringPeriod ceg false na duration The number of variable interest entities formed during the period. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false 2 2 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false xbrli:integerItemType integer The number of variable interest entities formed during the period. No authoritative reference available. false 11 Variable interest entity, ownership percentage (in hundredths) 3 us-gaap_VariableInterestEntityOwnershipPercentage us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false 1.00 1.00 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false us-types:percentItemType pure Percentage of the VIE's voting interest owned by the registrant. In general, a VIE is a corporation, partnership, trust, or any other legal structure used for business purposes that either (a) does not have equity investors with voting rights or (b) has equity investors that do not provide sufficient financial resources for the entity to support its activities. A VIE often holds financial assets, including loans or receivables, real estate or other property. A VIE may be essentially passive or it may engage in research and development or other activities on behalf of another company. No authoritative reference available. false 12 Guarantee obligations 3 us-gaap_GuaranteeObligationsMaximumExposure us-gaap true credit instant No definition available. false false false false false false false false false false false terselabel false 1 true true false false 10400000000 10400 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false xbrli:monetaryItemType monetary Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 45 -Paragraph 13 -Subparagraph b false 8 9 false HundredThousands UnKnown UnKnown false true