2.2.0.7 true Investments (Details 4) (USD $) 4043 - Disclosure - Investments (Details 4) true false In Millions false false 1 USD true false false false ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis xbrldi http://xbrl.org/2006/xbrldi ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 2 USD true false false false ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis xbrldi http://xbrl.org/2006/xbrldi ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis explicitMember false false ceg_ConstellationEnergyMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_ConstellationEnergyMember 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 $ false 3 USD true false false false ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis xbrldi http://xbrl.org/2006/xbrldi ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis explicitMember false false ceg_ConstellationEnergyMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_ConstellationEnergyMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 4 USD true false false false ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis xbrldi http://xbrl.org/2006/xbrldi ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis explicitMember false false ceg_ConstellationEnergyMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_ConstellationEnergyMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 5 USD true false false false ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis xbrldi http://xbrl.org/2006/xbrldi ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis explicitMember false false ceg_EDFMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_EDFMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 6 USD true false false false ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis xbrldi http://xbrl.org/2006/xbrldi ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis explicitMember false false ceg_EDFMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_EDFMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 7 USD true false false false ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis xbrldi http://xbrl.org/2006/xbrldi ceg_UNEMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis explicitMember false false ceg_EDFMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_EDFMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ 4 Equity in earnings of investments accounted for under the equity method of accounting 2 us-gaap_ScheduleOfEquityMethodInvestmentsLineItems 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 true 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 xbrli:stringItemType string Line items represent financial concepts included in a table. 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Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 159 -Paragraph 18 -Subparagraph f Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 20 -Subparagraph a (1) false 6 EDF's total required phased-in investment in joint venture 3 ceg_JointlyOwnedUtilityPlantTotalPhasedInInvestmentRequiredOfCoventurer ceg false debit duration Total of phased-in investment in joint venture required by the coventurer per the agreement. false false false false false false false false false false false terselabel false 1 false false false false 0 0 true 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 true true false false 625000000 625.0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false xbrli:monetaryItemType monetary Total of phased-in investment in joint venture required by the coventurer per the agreement. No authoritative reference available. false 7 Assets contributed to UNE 3 ceg_OtherSignificantCashAndNoncashTransactionValueOfConsiderationGiven2010 ceg false debit duration The value of the cash and noncash consideration given (for example, liability, equity) in a transaction. Noncash is defined... false false false false false false false false false false false terselabel false 1 false false false false 0 0 true false false 2 false true false false 91600000 91.6 true false false 3 false true false false 1700000 1.7 true false false 4 false true false false 48700000 48.7 true false false 5 false true false false 91600000 91.6 true false false 6 false true false false 175000000 175.0 true false false 7 false true false false 350000000 350.0 true false false xbrli:monetaryItemType monetary The value of the cash and noncash consideration given (for example, liability, equity) in a transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. No authoritative reference available. false 8 EDF's additional contribution to UNE to be made upon achievement of licensing milestones 3 ceg_JointlyOwnedUtilityPlantAdditionalAmountToBeContributedByCoventurer ceg false credit duration Additional investment required of coventurer according to the agreement. false false false false false false false false false false false terselabel false 1 false false false false 0 0 true 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 100000000 100.0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false xbrli:monetaryItemType monetary Additional investment required of coventurer according to the agreement. No authoritative reference available. false 9 UNE's capitalized construction work in process 3 us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress us-gaap true debit instant No definition available. false false false false false false false false false false false terselabel false 1 true true false false 510000000 510.0 true 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 xbrli:monetaryItemType monetary The period end amount of construction work in progress at a jointly owned electricity generation plant. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section C false 7 6 false HundredThousands UnKnown UnKnown false true