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xbrldi http://xbrl.org/2006/xbrldi us-gaap_PensionPlansDefinedBenefitMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis 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 Pension Benefits us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_PensionPlansDefinedBenefitMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 8 USD true false false false Qualified Pension Plans us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi ceg_QualifiedPensionPlansMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember false false Nine Mile dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_NineMilePointMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 9 USD true false false false Qualified Pension Plans us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi ceg_QualifiedPensionPlansMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember false false Other.. dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_OtherEntitiesMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 10 USD true false false false Qualified Pension Plans us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi ceg_QualifiedPensionPlansMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember false false Other.. dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_OtherEntitiesMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 11 USD true false false false Non-qualified Pension Plans us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi ceg_NonQualifiedPensionPlansMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 12 USD true false false false Non-qualified Pension Plans us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi ceg_NonQualifiedPensionPlansMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 13 USD true false false false Postretirement Benefits us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 $ false 14 USD true false false false Postretirement Benefits us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 $ false 15 USD true false false false Postretirement Benefits us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember us-gaap_DefinedBenefitPlansDisclosuresDefinedBenefitPlansAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 $ 2 Pension, Postretirement, Other Postemployment, and Employee Savings Plan Benefits 0 ceg_PensionPostretirementAndEmployeeSavingsPlanBenefitsDisclosureAbstract 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 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 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 15 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 3 Pension benefits 1 us-gaap_DefinedBenefitPensionPlanCurrentAndNoncurrentLiabilities 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 411700000 411700000 false false false 2 true true false false 411700000 411700000 false false false 3 true true false false 936700000 936700000 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary This represents the entire liability recognized in the balance sheet that is associated with the defined benefit pension plans. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph c Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 6 false 4 Postretirement benefits 1 us-gaap_OtherPostretirementDefinedBenefitPlanLiabilitiesCurrentAndNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false terselabel false 1 false true false false 322300000 322300000 false false false 2 false true false false 322300000 322300000 false false false 3 false true false false 415400000 415400000 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary This represents the entire liability recognized in the balance sheet that is associated with other postretirement defined benefit plans (excluding pension plans). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph c Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 6 false 5 Postemployment benefits 1 us-gaap_PostemploymentBenefitsLiabilityCurrentAndNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false terselabel false 1 false true false false 50600000 50600000 false false false 2 false true false false 50600000 50600000 false false false 3 false true false false 59900000 59900000 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary The carrying amount as of the balance sheet date of the obligations recognized for the various benefits provided to former or inactive employees, their beneficiaries, and covered dependents after employment but before retirement. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 5 -Paragraph 9 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 112 -Paragraph 4, 5, 6 false 6 Total defined benefit obligations 1 us-gaap_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesCurrentAndNoncurrent us-gaap true credit instant No definition available. false false false false false false false false false false false terselabel false 1 false true false false 784600000 784600000 false false false 2 false true false false 784600000 784600000 false false false 3 false true false false 1412000000 1412000000 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary This represents the entire liability recognized in the balance sheet that is associated with the defined benefit pension plans and other postretirement and postemployment benefit plans. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph c Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 6 false 7 Less: Amount recorded in other current liabilities 1 ceg_PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesCurrent ceg false credit instant This represents the current liability recognized in the balance sheet that is associated with the defined benefit pension... false false false false false false false false false false true negated false 1 false true false false 40700000 40700000 false false false 2 false true false false 40700000 40700000 false false false 3 false true false false 57700000 57700000 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary This represents the current liability recognized in the balance sheet that is associated with the defined benefit pension plans and other postretirement and postemployment benefit plans. No authoritative reference available. false 8 Total noncurrent defined benefit obligations 1 ceg_DefinedBenefitObligations ceg false credit instant For classified balance sheets this represents the noncurrent liability for underfunded plans recognized in the balance sheet... false false false false false false false false false false false totallabel false 1 false true false false 743900000 743900000 false false false 2 false true false false 743900000 743900000 false false false 3 false true false false 1354300000 1354300000 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary For classified balance sheets this represents the noncurrent liability for underfunded plans recognized in the balance sheet that is associated with the defined benefit pension plans, other postretirement defined benefit plans and other postemployment benefits (i.e. benefits for disabled and their dependents). No authoritative reference available. true 9 Age limit on January 1, 2002 under which future retirees' contributions are capped at the 2002 level (in years) 1 ceg_FutureRetireeMedicalCoverageContributionCapSpecifiedAgeLimit ceg false na duration Maximum age of retirees as of January 1, 2002 for which contributions for retiree medical coverage are capped at the 2002... 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 55 55 false false false 3 false false false false 0 0 false 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 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 15 false false false false 0 0 true false false xbrli:integerItemType integer Maximum age of retirees as of January 1, 2002 for which contributions for retiree medical coverage are capped at the 2002 level, expressed in years. No authoritative reference available. false 10 Reduction of Accumulated Postretirement Benefit Obligation due to the Medicare Prescription Drug Improvement and Modernization Act of 2003 1 us-gaap_PrescriptionDrugBenefitReductionInAccumulatedPostretirementBenefitObligationForSubsidy 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 28400000 28400000 false false false 2 false true false false 28400000 28400000 false false false 3 false false false false 0 0 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary Amount of the reduction in the accumulated postretirement benefit obligation for the government subsidy related to prescription drug benefits attributed to past service. Disclosure relates to the first period in which an employer includes the effects of the subsidy in measuring the accumulated postretirement benefit obligation and net periodic postretirement benefit cost. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS106-2 -Paragraph 21 -Subparagraph a false 11 Reduction of postretirement medical payments due to the Medicare Prescription Drug Improvement and Modernization Act of 2003 1 us-gaap_PrescriptionDrugBenefitEffectOfSubsidyOnNetPeriodicPostretirementBenefitCost 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 2800000 2800000 false false false 2 false true false false 2800000 2800000 false false false 3 false false false false 0 0 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary Amount of the effect of the government subsidy for prescription drug benefits on the measurement of net periodic postretirement benefit cost for the current period. That effect includes (1) any amortization of the actuarial experience gain, (2) the reduction in current period service cost due to the subsidy, and (3) the resulting reduction in interest cost on the accumulated postretirement benefit obligation as a result of the subsidy. Disclosure relates to the first period in which an employer includes the effects of the subsidy in measuring the accumulated postretirement benefit obligation and net periodic postretirement benefit cost. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS106-2 -Paragraph 21 -Subparagraph b false 13 Net pension and postretirement benefit costs 2 us-gaap_DefinedBenefitPlanDisclosureLineItems us-gaap true na duration No definition available. false false false false false true 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 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 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 15 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 14 Accumulated benefit obligation 3 us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation us-gaap true credit 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 false false false 0 0 false false false 4 false true false false 1361600000 1361600000 true false false 5 false true false false 1361600000 1361600000 true false false 6 false true false false 1640800000 1640800000 true false false 7 false false false false 0 0 true false false 8 false true false false 123700000 123700000 true false false 9 false true false false 1277500000 1277500000 true false false 10 false true false false 1417300000 1417300000 true false false 11 false true false false 84100000 84100000 true false false 12 false true false false 99800000 99800000 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary If aggregate disclosures are presented, the aggregate projected benefit obligation for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph C3 false 15 Fair value of assets 3 us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets 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 false false false 0 0 false false false 4 false true false false 1058100000 1058100000 true false false 5 false true false false 1058100000 1058100000 true false false 6 false true false false 867600000 867600000 true false false 7 false true false false 1258500000 1258500000 true false false 8 false true false false 63300000 63300000 true false false 9 false true false false 1058100000 1058100000 true false false 10 false true false false 804300000 804300000 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary If aggregate disclosures are presented, the aggregate fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets as of the measurement date of each statement of financial position presented. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 6 -Subparagraph b false 16 Unfunded obligation 3 ceg_UnfundedDefinedBenefitObligations ceg false credit instant The excess of the accumulated benefit obligation over the fair value of plan assets. 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 303500000 303500000 true false false 5 false true false false 303500000 303500000 true false false 6 false true false false 773200000 773200000 true false false 7 false false false false 0 0 true false false 8 false true false false 60400000 60400000 true false false 9 false true false false 219400000 219400000 true false false 10 false true false false 613000000 613000000 true false false 11 false true false false 84100000 84100000 true false false 12 false true false false 99800000 99800000 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary The excess of the accumulated benefit obligation over the fair value of plan assets. No authoritative reference available. false 17 Projected benefit obligation of pension liability increase (decrease) related to funded status adjustments 3 ceg_DefinedBenefitPlanEffectOfFundedStatusAdjustmentsOnProjectedBenefitObligation ceg false credit duration The amount of increase or decrease in the projected benefit obligation related to the defined benefit plan funded status... 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 -211700000 -211700000 [1] true false false 5 false true false false -49300000 -49300000 true false false 6 false true false false 590700000 590700000 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary The amount of increase or decrease in the projected benefit obligation related to the defined benefit plan funded status adjustments recorded during the period. No authoritative reference available. false 18 Accumulated benefit obligation of postretirement liability increase (decrease) related to funded status adjustments 3 ceg_DefinedBenefitPlanEffectOfFundedStatusAdjustmentsOnAccumulatedBenefitObligation ceg false credit duration The amount of increase or decrease in the accumulated benefit obligation related to the defined benefit plan funded status... 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 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 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 true false false -20900000 -20900000 [1] true false false 14 false true false false 1000000 1000000 true false false 15 false true false false -9500000 -9500000 true false false xbrli:monetaryItemType monetary The amount of increase or decrease in the accumulated benefit obligation related to the defined benefit plan funded status adjustments recorded during the period. No authoritative reference available. false 19 Impact of funded status adjustments on Accumulated Other Comprehensive Income (Loss), Pre-tax 3 ceg_AccumulatedOtherComprehensiveIncomeLossEffectOfFundedStatusAdjustmentsBeforeTax ceg false credit duration Pre-tax gain or loss adjustment to accumulated other comprehensive income or loss resulting from funded status adjustments to... false false false false false false false false false false false terselabel false 1 false true false false 232600000 232600000 [1] false false false 2 false true false false 48300000 48300000 false false false 3 false true false false -581200000 -581200000 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary Pre-tax gain or loss adjustment to accumulated other comprehensive income or loss resulting from funded status adjustments to the entity's defined benefit pension and/or other postretirement plans. No authoritative reference available. false 20 Impact of funded status adjustments on Accumulated Other Comprehensive Income (Loss), After-tax 3 ceg_AccumulatedOtherComprehensiveIncomeLossEffectOfFundedStatusAdjustmentsNetOfTax ceg false credit duration After-tax gain or loss adjustment to accumulated other comprehensive income or loss resulting from funded status adjustments... false false false false false false false false false false false terselabel false 1 false true false false 138000000 138000000 [1] false false false 2 false true false false 25400000 25400000 false false false 3 false true false false -347100000 -347100000 false 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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary After-tax gain or loss adjustment to accumulated other comprehensive income or loss resulting from funded status adjustments to the entity's defined benefit pension and/or other postretirement plans. No authoritative reference available. false 21 Change in benefit obligation 3 us-gaap_DefinedBenefitPlanChangeInBenefitObligationRollForward 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 false false false 3 false false false false 0 0 false 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 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 15 false false false false 0 0 true false false xbrli:stringItemType string A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. false 22 Benefit obligation, beginning balance 4 us-gaap_DefinedBenefitPlanBenefitObligation us-gaap true credit instant No definition available. false false false false false false false false true false false periodstartlabel 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 true false false 5 false true false false 1804300000 1804300000 [2] true false false 6 false true false false 1644200000 1644200000 [2] true false false 7 false false false false 0 0 [2] 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 415400000 415400000 [2] true false false 15 false true false false 421500000 421500000 [2] true false false xbrli:monetaryItemType monetary 1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. The projected benefit obligation is measured using assumptions as to future compensation levels if the pension benefit formula is based on those future compensation levels (pay-related, final-pay, final-average-pay, or career-average-pay plans). For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date. Prior to an employee's full eligibility date, the accumulated postretirement benefit obligation as of a particular date for an employee is the portion of the expected postretirement benefit obligation attributed to that employee's service rendered to that date; on and after the full eligibility date, the accumulated and expected postretirement benefit obligations for an employee are the same. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 6 -Subparagraph a Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph E1 false 23 Service cost 4 ceg_DefinedBenefitPlanBenefitObligationServiceCost ceg false credit duration The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during... 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 true false false 5 false true false false 50800000 50800000 [2] true false false 6 false true false false 55400000 55400000 [2] 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 6300000 6300000 [2] true false false 15 false true false false 6100000 6100000 [2] true false false xbrli:monetaryItemType monetary The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component increases the benefit obligation and is unaffected by the funded status of the plan. No authoritative reference available. false 24 Interest cost 4 ceg_DefinedBenefitPlanBenefitObligationInterestCost ceg false credit duration The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's... 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 true false false 5 false true false false 101100000 101100000 [2] true false false 6 false true false false 100200000 100200000 [2] 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 22600000 22600000 [2] true false false 15 false true false false 24000000 24000000 [2] true false false xbrli:monetaryItemType monetary The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation related to interest cost. No authoritative reference available. false 25 Plan amendments 4 us-gaap_DefinedBenefitPlanPlanAmendments us-gaap true credit 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 false false false 0 0 true false false 5 false true false false 2400000 2400000 [2] true false false 6 false true false false 12100000 12100000 [2] 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary The amount of increase or decrease due to a change in the terms of an existing plan or the initiation of a new plan. A plan amendment may increase or decrease benefits, including those attributed to years of service already rendered. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a false 26 Plan participants' contributions 4 us-gaap_DefinedBenefitPlanContributionsByPlanParticipants us-gaap true credit 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 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 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 10200000 10200000 [2] true false false 15 false true false false 10800000 10800000 [2] true false false xbrli:monetaryItemType monetary The amount of contributions made by plan participants. Under a contributory plan active employees or retirees contribute part of the cost. In some contributory plans, those wishing to be covered must contribute; in others, the contributions result in increased benefits. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph b false 27 Actuarial loss (gain) 4 ceg_DefinedBenefitPlanActuarialGainsLosses ceg false debit duration The amount of actuarial gains or losses that are related to defined benefit plan obligations. false false false false false false false false false false true negated 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 true false false 5 false true false false 55800000 55800000 [2] true false false 6 false true false false 102400000 102400000 [2] 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 1000000 1000000 [2] true false false 15 false true false false -9500000 -9500000 [2] true false false xbrli:monetaryItemType monetary The amount of actuarial gains or losses that are related to defined benefit plan obligations. No authoritative reference available. false 28 Separation of CENG Plan 4 us-gaap_DefinedBenefitPlanDivestituresBenefitObligation us-gaap true debit duration No definition available. false false false false false false false false false false true negated 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 true false false 5 false true false false -410500000 -410500000 [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 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 -98600000 -98600000 [2] true false false 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary The amount of decrease in the plan benefit obligation attributed to the sale, liquidation, spin-off or other divestiture of a corporate division or subsidiary. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a false 29 Settlements 4 us-gaap_DefinedBenefitPlanSettlementsBenefitObligation us-gaap true debit duration No definition available. false false false false false false false false false false true negated 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 true false false 5 false true false false -19000000 -19000000 [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 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 15 false false false false 0 0 true false false xbrli:monetaryItemType monetary The amount of decrease that relates to an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include (a) making lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and (b) purchasing nonparticipating annuity contracts. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 88 -Paragraph 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a false 30 Special termination benefits 4 us-gaap_DefinedBenefitPlanSpecialTerminationBenefits us-gaap true credit 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 false false false 0 0 true false false 5 false true false false 100000 100000 [2] true false false 6 false true false false 2200000 2200000 [2] 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 15 false true false false 800000 800000 [2] true false false xbrli:monetaryItemType monetary The amount of increase related to special termination benefits offered to and accepted by employees in connection with their termination of employment that are only offered for a short period of time. A situation involving termination benefits may also involve a curtailment. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 88 -Paragraph 15 false 31 Benefits paid 4 us-gaap_DefinedBenefitPlanBenefitsPaid us-gaap true debit duration No definition available. false false false false false false false false false false true negated 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 true false false 5 false true false false -115200000 -115200000 [2],[3] true false false 6 false true false false -112200000 -112200000 [2],[3] 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 -34600000 -34600000 [2],[4] true false false 15 false true false false -38300000 -38300000 [2],[4] true false false xbrli:monetaryItemType monetary The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a, b Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 106 -Paragraph 518 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 87 -Paragraph 264 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number FAS106-2 -Paragraph 22 false 32 Benefit obligation, ending balance 4 us-gaap_DefinedBenefitPlanBenefitObligation us-gaap true credit instant No definition available. false false false false false false false false false true false periodendlabel 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 true true false false 1469800000 1469800000 [2] true false false 5 true true false false 1469800000 1469800000 [2] true false false 6 true true false false 1804300000 1804300000 [2] true false false 7 false false false false 0 0 [2] 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 true true false false 322300000 322300000 [2] true false false 14 true true false false 322300000 322300000 [2] true false false 15 true true false false 415400000 415400000 [2] true false false xbrli:monetaryItemType monetary 1) For defined benefit pension plans, the benefit obligation is the projected benefit obligation, which is the actuarial present value as of a date of all benefits attributed by the pension benefit formula to employee service rendered prior to that date. The projected benefit obligation is measured using assumptions as to future compensation levels if the pension benefit formula is based on those future compensation levels (pay-related, final-pay, final-average-pay, or career-average-pay plans). For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same. 2) For other postretirement defined benefit plans, the benefit obligation is the accumulated postretirement benefit obligation, which is the actuarial present value of benefits attributed to employee service rendered to a particular date. Prior to an employee's full eligibility date, the accumulated postretirement benefit obligation as of a particular date for an employee is the portion of the expected postretirement benefit obligation attributed to that employee's service rendered to that date; on and after the full eligibility date, the accumulated and expected postretirement benefit obligations for an employee are the same. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph a Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 6 -Subparagraph a Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph E1 false 1 We performed a remeasurement of our pension and postretirement obligations at November 6, 2009 in connection with the separation of a portion of those plans upon the deconsolidation of CENG. 2 Amounts reflect projected benefit obligation for pension benefits and accumulated postretirement benefit obligations for postretirement benefits. 3 Pension benefits paid include annuity payments and lump-sum distributions. 4 Postretirement benefits paid are net of Medicare Part D reimbursements. 15 30 false NoRounding UnKnown UnKnown false true