2.2.0.7 true Other Events (Details 7) (USD $) 4026 - Disclosure - Other Events (Details 7) true false 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 us-gaap_SubsidiariesMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_SubsidiariesMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 $ 4 Loss Contingencies 2 us-gaap_LossContingenciesLineItems 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 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 Before-tax charge related to the one-time $170 residential electric customer credit related to the Maryland settlement agreement 3 ceg_BeforeTaxChargeRelatedToOneTimeResidentialElectricCustomerCreditRelatedToSettlementAgreement ceg false debit duration This element represents the charge that is related to the one-time residential electric customer credit which is associated... false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 true true false false 189100000 189100000 true false false xbrli:monetaryItemType monetary This element represents the charge that is related to the one-time residential electric customer credit which is associated with the Maryland settlement agreement, before tax. No authoritative reference available. false 6 After-tax charge related to the one-time $170 residential electric customer credit related to the Maryland settlement agreement 3 ceg_AfterTaxChargeRelatedToOneTimeResidentialElectricCustomerCreditRelatedToSettlementAgreement ceg false debit duration This element represents the charge that is related to the one-time residential electric customer credit which is associated... false false false false false false false false false false false terselabel false 1 false true false false 1200000 1200000 false false false 2 false false false false 0 0 true false false xbrli:monetaryItemType monetary This element represents the charge that is related to the one-time residential electric customer credit which is associated with the Maryland settlement agreement, net of tax. No authoritative reference available. false 7 Amount of the per customer one-time residential electric customer credit related to the Maryland settlement agreement (in actual dollars) 3 ceg_ResidentialElectricCustomerCredit ceg false debit duration This element represents the amount of the per customer one-time residential electric customer credit that is related to... false false false false false false false false false false false terselabel false 1 false true false false 170 170 false false false 2 false true false false 170 170 true false false xbrli:monetaryItemType monetary This element represents the amount of the per customer one-time residential electric customer credit that is related to Maryland settlement agreement. No authoritative reference available. false 8 Potential future liability BGE customers are relieved of for decommissioning Calvert Cliffs Unit 1 and Unit 2 3 ceg_PotentialFutureLiabilityOfCustomerRelieved ceg false credit instant This element represents the potential future liability that a subsidiary's customers are relieved of for decommissioning two... 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 520000000 520000000 true false false xbrli:monetaryItemType monetary This element represents the potential future liability that a subsidiary's customers are relieved of for decommissioning two electric generation units. No authoritative reference available. false 9 Annual nuclear decommissioning charge to be collected from all electric customers through 2016 3 ceg_CollectionOfAnnualNuclearDecommissioningCharge ceg false credit duration This element represents the annual nuclear decommissioning charge that the company continues to collect from customers. 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 18700000 18700000 true false false xbrli:monetaryItemType monetary This element represents the annual nuclear decommissioning charge that the company continues to collect from customers. No authoritative reference available. false 10 Approximate amount of residential return portion of the SOS administrative charge to be collected between June 1, 2008 and May 31, 2010 3 ceg_ResidentialReturnPortionOfSOSAdministrativeChargeCollectionResumed ceg false credit duration This element represents the approximate total of the resumed collection of the residential return portion of the SOS... 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 40000000 40000000 true false false xbrli:monetaryItemType monetary This element represents the approximate total of the resumed collection of the residential return portion of the SOS administrative charge. No authoritative reference available. false 11 Rate increase cap ordered by the Maryland PSC for BGE's electric distribution case to be filed at any time beginning in January 2010 (in hundredths) 3 ceg_RateIncreaseCapForMaximumIncreaseInFirstElectricDistributionRateCase ceg false na instant This element represents the rate increase cap imposed on a public utility subsidiary by the public service commission. 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 us-types:percentItemType pure This element represents the rate increase cap imposed on a public utility subsidiary by the public service commission. No authoritative reference available. false 12 Reduction in depreciation expense based on revision of depreciation rates 3 ceg_ReductionInDepreciationOnRevisionOfDepreciationRate ceg false credit duration This element represents the reduction in depreciation expense for the period due to the revision of depreciation rates for... false false false false false false false false false false false terselabel false 1 false false false false 0 0     false false false 2 true true false false 14000000 14000000 true false false xbrli:monetaryItemType monetary This element represents the reduction in depreciation expense for the period due to the revision of depreciation rates for regulatory and financial purposes. No authoritative reference available. false 2 9 false NoRounding UnKnown UnKnown false true