2.2.0.7 true Other Events (Details 4) (USD $) 4023 - Disclosure - Other Events (Details 4) 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 false false 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 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 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 4 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 5 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 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 6 true false false false ceg_SeniorNoteHeldByFormerMergerCandidate14PercentMember us-gaap_LongtermDebtTypeAxis xbrldi http://xbrl.org/2006/xbrldi ceg_SeniorNoteHeldByFormerMergerCandidate14PercentMember us-gaap_LongtermDebtTypeAxis explicitMember Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 false 7 USD true false false false ceg_MerchantEnergyBusinessMember us-gaap_StatementBusinessSegmentsAxis xbrldi http://xbrl.org/2006/xbrldi ceg_MerchantEnergyBusinessMember us-gaap_StatementBusinessSegmentsAxis explicitMember Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 8 USD true false false false ceg_CEPMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_CEPMember dei_LegalEntityAxis explicitMember Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 9 USD true false false false ceg_CEPMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_CEPMember dei_LegalEntityAxis explicitMember Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 10 USD true false false false ceg_CEPMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_CEPMember dei_LegalEntityAxis explicitMember Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 11 USD true false false false ceg_ShippingJVMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_ShippingJVMember dei_LegalEntityAxis explicitMember Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 12 USD true false false false ceg_OtherMarketableSecuritiesMember us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsMajorTypesOfTradingSecuritiesAndAssetsAxis xbrldi http://xbrl.org/2006/xbrldi ceg_OtherMarketableSecuritiesMember us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsMajorTypesOfTradingSecuritiesAndAssetsAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 13 USD true false false false ceg_OtherMarketableSecuritiesMember us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsMajorTypesOfTradingSecuritiesAndAssetsAxis xbrldi http://xbrl.org/2006/xbrldi ceg_OtherMarketableSecuritiesMember us-gaap_ScheduleOfTradingSecuritiesAndOtherTradingAssetsMajorTypesOfTradingSecuritiesAndAssetsAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 14 USD true false false false ceg_DistrictChilledWaterFacilityMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis xbrldi http://xbrl.org/2006/xbrldi ceg_DistrictChilledWaterFacilityMember us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ 5 Asset Impairment 3 ceg_AssetImpairmentChargesLineitems ceg false 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 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 6 Impairment charge 4 us-gaap_AssetImpairmentCharges us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 true true false false 124700000 124.7 false false false 4 true true false false 741800000 741.8 false false false 5 true true false false 20200000 20.2 false false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 true true false false 14000000 14.0 true false false 9 true true false false 54700000 54.7 true false false 10 true true false false 69700000 69.7 true false false 11 true true false false 59000000 59.0 true false false 12 true true false false 7000000 7.0 true false false 13 true true false false 500000 0.5 true false false 14 true true false false 20000000 20.0 true false false xbrli:monetaryItemType monetary The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 45, 46, 47 false 7 Percentage interest sold (in hundredths) 4 ceg_PercentageInterestSold ceg false na duration This element represents the percentage of interest in affiliates sold. 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     false false false 3 false false false false 0 0     false false false 4 false false false false 0 0     false false false 5 false false false false 0 0     false 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 9 false false false false 0 0     true false false 10 false false false false 0 0     true false false 11 false true false false 0.50 0.50 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false us-types:percentItemType pure This element represents the percentage of interest in affiliates sold. No authoritative reference available. false 8 Equity method investment closing price 4 us-gaap_EquityMethodInvestmentsFairValueDisclosure us-gaap true debit instant 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 false false false 3 false true false false 5100000000 5100.0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false true false false 10000000 10.0 true false false 9 false true false false 73000000 73.0 true false false 10 false true false false 17000000 17.0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investments accounted for under the equity method of accounting as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 6 -Subparagraph b false 9 Carrying value, equity method investment 4 us-gaap_EquityMethodInvestments us-gaap true debit instant No definition available. false false false false false false false false false false false terselabel false 1 false true false false 414100000 414.1 false false false 2 false false false false 0 0 false false false 3 false true false false 5640300000 5640.3 false false false 4 false true false false 414100000 414.1 false false false 5 false false false false 0 0 false false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false true false false 24000000 24.0 true false false 9 false true false false 128000000 128.0 true false false 10 false true false false 87000000 87.0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment losses recognized. No authoritative reference available. false 10 Impairment charge net of noncontrolling interest 4 ceg_ImpairmentChargeNetOfNoncontrollingInterest ceg false debit duration This element represents the impairment charge, net of the non-controlling interest. 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 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false true false false 12000000 12.0 true false false xbrli:monetaryItemType monetary This element represents the impairment charge, net of the non-controlling interest. No authoritative reference available. false 11 Impairment charge noncontrolling interest impact 4 ceg_ImpairmentChargeNoncontrollingInterestImpact ceg false debit duration This element represents the noncontrolling interest impairment charge. 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 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false true false false 8000000 8.0 true false false xbrli:monetaryItemType monetary This element represents the noncontrolling interest impairment charge. No authoritative reference available. false 12 Goodwill impairment 4 us-gaap_GoodwillImpairmentLoss us-gaap true debit 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 false false false 3 false false false false 0 0 false false false 4 false true false false -266500000 -266.5 false false false 5 false false false false 0 0 false false false 6 false false false false 0 0 true false false 7 false true false false 266500000 266.5 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 45 -Subparagraph e(2) Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 43 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 47 -Subparagraph b Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 142 -Paragraph 20 false 13 Impairment losses on nuclear decommissioning trust assets 4 ceg_ImpairmentLossesOnNuclearDecommissioningTrustAssets ceg false debit duration This element represents an impairment charge related to the nuclear decommissioning trust fund assets, pre-tax. false false false false false false false false false false false terselabel false 1 false true false false 122000000 122.0 false false false 2 false true false false 12000000 12.0 false false false 3 false true false false 62600000 62.6 false false false 4 false true false false 165000000 165.0 false false false 5 false true false false 8500000 8.5 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary This element represents an impairment charge related to the nuclear decommissioning trust fund assets, pre-tax. No authoritative reference available. false 14 Other costs 2 ceg_OtherCosts ceg false debit duration This element represents other costs, such as write-offs of advances, lease terminations, and write-downs of long-lived... false false false false false false false false false false false terselabel false 1 false true false false 14000000 14.0 false false false 2 false false false false 0 0 false false false 3 false true false false 31200000 31.2 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary This element represents other costs, such as write-offs of advances, lease terminations, and write-downs of long-lived assets. No authoritative reference available. false 15 Loss on Redemption of Zero Coupon Senior Notes 2 ceg_LossOnRedemptionOfZeroCouponSeniorNotesAbstract ceg false 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 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 16 Pre-tax loss on redemption of zero coupon bonds 3 us-gaap_GainsLossesOnExtinguishmentOfDebt us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false -16000000 -16.0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary Amount represents the difference between the fair value of the payments made and the carrying amount of the debt at the time of its extinguishment. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 26 -Paragraph 20, 21 false 17 Merger, Termination and Strategic Alternatives Costs 2 ceg_MergerTerminationAndStrategicAlternativesCostsAbstract ceg false 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 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 18 Merger termination and strategic alternatives costs 3 ceg_MergerAndStrategicAlternativesCosts ceg false debit duration Amount of costs related to a merger and our pursuit of other strategic alternatives to the merger that were charged 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 false false false 3 false true false false 145800000 145.8 false false false 4 false true false false 1204400000 1204.4 false false false 5 false false false false 0 0     false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary Amount of costs related to a merger and our pursuit of other strategic alternatives to the merger that were charged to expense during the period. No authoritative reference available. false 19 Interest rate (in hundredths) 3 us-gaap_DebtInstrumentInterestRateStatedPercentage us-gaap true na instant No definition available. false false false false false false false false false false false terselabel false 1 false true false false 0.0620 0.0620 false false false 2 false false false false 0 0 false false false 3 false true false false 0.0620 0.0620 false false false 4 false true false false 0.0620 0.0620 false false false 5 false false false false 0 0 false false false 6 false true false false 0.14 0.14 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false us-types:percentItemType pure Interest rate stated in the contractual debt agreement. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 false 20 Workforce Reduction Costs, 2 ceg_WorkforceReductionCostsAbstract ceg false 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 false false false 3 false false false false 0 0 false false false 4 false false false false 0 0 false false false 5 false false false false 0 0 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 21 Workforce reduction costs 3 us-gaap_SeveranceCosts us-gaap true debit duration No definition available. false false false false false false false false false false false terselabel false 1 true true false false 19700000 19.7 false false false 2 false false false false 0 0 false false false 3 true true false false 12600000 12.6 false false false 4 true true false false 22200000 22.2 false false false 5 true true false false 2300000 2.3 false 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 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary The charge against earnings in the period for known and estimated costs of termination benefits provided to current employees that are involuntarily terminated under a benefit arrangement associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, excluding costs or losses pertaining to an entity newly acquired in a business combination or a discontinued operation as defined by generally accepted accounting principles and costs associated with one-time termination benefits. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5-8 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 146 -Paragraph 8-13, 20 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section P -Subsection 3, 4 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS146-1 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 112 -Paragraph 7 false 14 17 false HundredThousands UnKnown UnKnown false true