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The difference in basis, attributable to different capitalization of costs, depreciation, or amortization methodologies, will increase future taxable income when such basis difference is realized. Capital assets include but are not limited to assets such as land, real estate, leasehold improvements, machinery and equipment and furniture and fixtures. 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No authoritative reference available. false 5 Regulatory assets, net 2 us-gaap_DeferredTaxLiabilitiesRegulatoryAssets 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 263000000 263.0 false false false 2 false true false false 295500000 295.5 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The amount as of the balance sheet date of the estimated future tax effects attributable to the difference between the tax basis and the basis in accordance with generally accepted accounting principles of regulatory assets which will increase future taxable income when such basis difference reverses. 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Deferred tax consequences are future tax effects on income taxes as measured by the applicable enacted tax rate and provisions of the enacted tax law resulting from temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 -Subparagraph a false 7 Investment in CENG 2 ceg_DeferredTaxLiabilitiesEquityMethodInvestment ceg false credit instant The amount as of the balance sheet date of the estimated future tax effects attributable to CENG relating to the difference... false false false false false false false false false false false terselabel false 1 false true false false 1802700000 1802.7 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The amount as of the balance sheet date of the estimated future tax effects attributable to CENG relating to the difference between the tax basis and the basis in accordance with generally accepted accounting principles of equity method investments retained at carrying value which will increase future taxable income when such basis difference reverses. No authoritative reference available. false 8 Other 2 us-gaap_DeferredTaxLiabilitiesOther 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 33100000 33.1 false false false 2 false true false false 126600000 126.6 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The cumulative amount of the estimated future tax effects attributable to other temporary differences not otherwise specified in this taxonomy that were expensed for tax purposes but capitalized in conformity with generally accepted accounting principles, or which were recognized as revenue under GAAP but not for tax purposes, which will reverse in future periods. 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A taxable temporary difference is a difference between the tax basis and the carrying amount of an asset or liability in the financial statements prepared in accordance with generally accepted accounting principles that will result in taxable amounts in one or more future periods. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 42, 43 true 10 Deferred tax assets 2 us-gaap_ComponentsOfDeferredTaxAssetsAbstract 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 xbrli:stringItemType string No definition available. false 11 Asset retirement obligation 2 us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAssetRetirementObligations 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 7900000 7.9 false false false 2 false true false false 391600000 391.6 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The tax effect as of the balance sheet date of the amount of the estimated future tax deductions arising from estimated costs required to satisfy asset retirement obligations, which can only be deducted for tax purposes when relevant costs (such as closure and postclosure costs) are actually incurred, and which can only be realized if sufficient tax basis income is generated in future periods to enable the deduction to be taken. 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Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 true 17 Total deferred tax liability, net 2 us-gaap_DeferredTaxAssetsLiabilitiesNet us-gaap true debit instant No definition available. false false false false false false false false false false true negatedtotal false 1 false true false false 3077600000 3077.6 false false false 2 false true false false 409000000 409.0 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary For entities that net deferred tax assets and tax liabilities, represents the unclassified net amount of deferred tax assets and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities. A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 42, 43 true 18 Less: Current portion of deferred tax (asset)/liability 2 us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent us-gaap true debit instant No definition available. false false false false false false false false false false true negated false 1 false true false false -127900000 -127.9 false false false 2 false true false false -268000000 -268.0 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary For entities that net deferred tax assets and tax liabilities, represents the net amount of deferred tax assets (after reduction for valuation allowance) and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities that are classified as current in the financial statements, or that are expected to reverse in the next twelve months (or normal operating cycle, if longer). A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods. In a classified statement of financial position, an enterprise shall separate deferred tax liabilities and assets into a current amount and a noncurrent amount. Deferred tax liabilities and assets shall be classified as current or noncurrent based on the classification of the related asset or liability for financial reporting. A deferred tax liability or asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to carryforwards, shall be classified according to the expected reversal date of the temporary difference. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 41, 42, 43 false 19 Long-term portion of deferred tax liability, net 2 us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent us-gaap true debit instant No definition available. false false false false false false false false false false true negatedtotal false 1 false true false false 3205500000 3205.5 false false false 2 false true false false 677000000 677.0 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary For entities that net deferred tax assets and tax liabilities, represents the net amount of deferred tax assets (after reduction for valuation allowance) and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities that are classified as noncurrent in the financial statements, or that are expected to reverse after the next twelve months (or beyond the normal operating cycle, if longer). A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods. In a classified statement of financial position, an enterprise shall separate deferred tax liabilities and assets into a current amount and a noncurrent amount. Deferred tax liabilities and assets shall be classified as current or noncurrent based on the classification of the related asset or liability for financial reporting. A deferred tax liability or asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to carryforwards, shall be classified according to the expected reversal date of the temporary difference. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 41, 42, 43 true 20 Unrecognized Tax Benefits 2 us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward 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 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 21 Total unrecognized tax benefits, beginning balance 2 us-gaap_UnrecognizedTaxBenefits us-gaap true credit instant No definition available. false false false false false false false false true false false periodstartlabel false 1 false true false false 189700000 189.7 [1] false false false 2 false true false false 114500000 114.5 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The gross amount of unrecognized tax benefits (tax reductions recognized in financial reports but excluded from tax returns) pertaining to uncertain tax positions taken in tax returns as of the beginning balance sheet date, excluding amounts pertaining to examined tax returns. 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Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 21 -Subparagraph a(1) false 25 Reductions in tax positions related to audit settlements 2 us-gaap_UnrecognizedTaxBenefitsDecreasesResultingFromSettlementsWithTaxingAuthorities 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 true false false -21500000 -21.5 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The gross amount of decreases in unrecognized tax benefits resulting from settlements with taxing authorities. 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No authoritative reference available. false 29 Outstanding tax claim benefits 2 ceg_OutstandingTaxClaimBenefits ceg false credit instant Amount of outstanding tax claims for which no tax benefit was recorded on Balance Sheet because refunds were not received and... false false false false false false false false false false false terselabel false 1 false true false false 65800000 65.8 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary Amount of outstanding tax claims for which no tax benefit was recorded on Balance Sheet because refunds were not received and the claims do not meet the "more-likely-than-not" threshold. 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No authoritative reference available. false 31 Amount of potential decrease in income tax expense if unrecognized tax benefits were realized 2 us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate 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 177000000 177.0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate. 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No authoritative reference available. false 37 Deferred tax liabilities 2 us-gaap_ComponentsOfDeferredTaxLiabilitiesAbstract 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 xbrli:stringItemType string No definition available. false 38 Net property, plant and equipment 2 us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment 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 920100000 920.1 false false false 2 false true false false 604400000 604.4 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The amount as of the balance sheet date of the estimated future tax effects attributable to the difference between the tax basis of capital assets and the basis of capital assets computed in accordance with generally accepted accounting principles. The difference in basis, attributable to different capitalization of costs, depreciation, or amortization methodologies, will increase future taxable income when such basis difference is realized. Capital assets include but are not limited to assets such as land, real estate, leasehold improvements, machinery and equipment and furniture and fixtures. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 11 -Subparagraph d, e, f false 40 Regulatory assets, net 2 us-gaap_DeferredTaxLiabilitiesRegulatoryAssets 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 263000000 263.0 false false false 2 false true false false 295500000 295.5 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The amount as of the balance sheet date of the estimated future tax effects attributable to the difference between the tax basis and the basis in accordance with generally accepted accounting principles of regulatory assets which will increase future taxable income when such basis difference reverses. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 11 -Subparagraph d false 43 Other 2 us-gaap_DeferredTaxLiabilitiesOther 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 -55100000 -55.1 false false false 2 false true false false 32500000 32.5 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The cumulative amount of the estimated future tax effects attributable to other temporary differences not otherwise specified in this taxonomy that were expensed for tax purposes but capitalized in conformity with generally accepted accounting principles, or which were recognized as revenue under GAAP but not for tax purposes, which will reverse in future periods. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 11 -Subparagraph a, d, e false 44 Total deferred tax liabilities 2 us-gaap_DeferredTaxLiabilities us-gaap true credit instant No definition available. false false false false false false false false false false false totallabel false 1 false true false false 1128000000 1128.0 false false false 2 false true false false 932400000 932.4 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The cumulative amount of all deferred tax liabilities, which result from applying the applicable tax rate to net taxable temporary differences pertaining to each jurisdiction to which the entity is obligated to pay income tax. A taxable temporary difference is a difference between the tax basis and the carrying amount of an asset or liability in the financial statements prepared in accordance with generally accepted accounting principles that will result in taxable amounts in one or more future periods. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 42, 43 true 45 Deferred tax assets 2 us-gaap_ComponentsOfDeferredTaxAssetsAbstract 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 xbrli:stringItemType string No definition available. false 47 Defined benefit obligations 2 us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits 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 -23700000 -23.7 false false false 2 false true false false 30800000 30.8 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The sum of the tax effects as of the balance sheet date of the amount of the estimated future tax deductions arising from all employee compensation and benefits costs, which can only be deducted for tax purposes when the actual costs are incurred, and which can only be realized if sufficient tax-basis income is generated in future periods to enable the deduction to be taken. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 11 -Subparagraph b false 49 Deferred investment tax credits 2 ceg_DeferredTaxAssetsInvestmentTaxCredits ceg false debit instant This element represents the deferred tax liabilities resulting from investment tax credits as of the balance sheet date. false false false false false false false false false false false terselabel false 1 false true false false 3800000 3.8 false false false 2 false true false false 4300000 4.3 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary This element represents the deferred tax liabilities resulting from investment tax credits as of the balance sheet date. No authoritative reference available. false 50 Other 2 us-gaap_DeferredTaxAssetsOther 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 71500000 71.5 false false false 2 false true false false 13800000 13.8 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The tax effect as of the balance sheet date of the amount of estimated future tax deductions arising from other temporary differences not otherwise specified in the taxonomy. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 false 51 Total deferred tax assets 2 us-gaap_DeferredTaxAssetsNet us-gaap true debit instant No definition available. false false false false false false false false false false false totallabel false 1 false true false false 51600000 51.6 false false false 2 false true false false 48900000 48.9 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary The aggregate tax effects as of the balance sheet date of all future tax deductions arising from temporary differences between tax basis and generally accepted accounting principles basis recognition of assets, liabilities, revenues and expenses, which can only be deducted for tax purposes when permitted under enacted tax laws; net of deducting the allocated valuation allowance, if any, to reduce such amount to net realizable value. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 43 true 52 Total deferred tax liability, net 2 us-gaap_DeferredTaxAssetsLiabilitiesNet us-gaap true debit instant No definition available. false false false false false false false false false false true negatedtotal false 1 false true false false 1076400000 1076.4 false false false 2 false true false false 883500000 883.5 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary For entities that net deferred tax assets and tax liabilities, represents the unclassified net amount of deferred tax assets and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities. A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 42, 43 true 53 Less: Current portion of deferred tax (asset)/liability 2 us-gaap_DeferredTaxAssetsLiabilitiesNetCurrent us-gaap true debit instant No definition available. false false false false false false false false false false true negated false 1 false true false false -11200000 -11.2 false false false 2 false true false false 40200000 40.2 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary For entities that net deferred tax assets and tax liabilities, represents the net amount of deferred tax assets (after reduction for valuation allowance) and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities that are classified as current in the financial statements, or that are expected to reverse in the next twelve months (or normal operating cycle, if longer). A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods. In a classified statement of financial position, an enterprise shall separate deferred tax liabilities and assets into a current amount and a noncurrent amount. Deferred tax liabilities and assets shall be classified as current or noncurrent based on the classification of the related asset or liability for financial reporting. A deferred tax liability or asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to carryforwards, shall be classified according to the expected reversal date of the temporary difference. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 41, 42, 43 false 54 Long-term portion of deferred tax liability, net 2 us-gaap_DeferredTaxAssetsLiabilitiesNetNoncurrent us-gaap true debit instant No definition available. false false false false false false false false false false true negatedtotal false 1 false true false false 1087600000 1087.6 false false false 2 false true false false 843300000 843.3 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary For entities that net deferred tax assets and tax liabilities, represents the net amount of deferred tax assets (after reduction for valuation allowance) and liabilities as of the balance sheet date, which result from applying the applicable enacted tax rate to net temporary differences and carryforwards pertaining to assets or liabilities that are classified as noncurrent in the financial statements, or that are expected to reverse after the next twelve months (or beyond the normal operating cycle, if longer). A temporary difference is a difference between the tax basis of an asset or liability and its carrying amount in the financial statements prepared in accordance with generally accepted accounting principles that will reverse in ensuing periods. In a classified statement of financial position, an enterprise shall separate deferred tax liabilities and assets into a current amount and a noncurrent amount. Deferred tax liabilities and assets shall be classified as current or noncurrent based on the classification of the related asset or liability for financial reporting. A deferred tax liability or asset that is not related to an asset or liability for financial reporting, including deferred tax assets related to carryforwards, shall be classified according to the expected reversal date of the temporary difference. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 41, 42, 43 true 55 Unrecognized Tax Benefits 2 us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward 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 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 70 Accrued interest and penalties recognized in balance sheet 2 us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued 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 1600000 1.6 false false false 2 true true false false 700000 0.7 false false false 3 false false false false 0 0 false false false xbrli:monetaryItemType monetary This element represents the total of accruals as of the date of the statement of financial position for interest recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity and the amount of statutory penalties for a tax position claimed or expected to be claimed by the entity, in its tax return, that does not meet the minimum statutory threshold to avoid payment of penalties. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 21 -Subparagraph c Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 15, 16 false 71 Constellation Energy 0 na true na na No definition available. false true false false false false false false false false false http://www.constellation.com/role/disclosuretaxesdetails2 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 false 6 USD true false false false Constellation Energy dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_ConsolidatedEntitiesExcludingBGEMember 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 $ na No definition available. No authoritative reference available. false 90 Unrecognized Tax Benefits 2 us-gaap_ReconciliationOfUnrecognizedTaxBenefitsExcludingAmountsPertainingToExaminedTaxReturnsRollForward 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 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 98 Percent of membership interest in CENG sold (in hundredths) 2 ceg_MembershipInterestSalePercentage ceg false na instant The percentage of ownership interest in a subsidiary that was sold during the period. false false false false false false false false false false false terselabel false 1 false true false false 0.4999 0.4999 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 false false false us-types:percentItemType pure The percentage of ownership interest in a subsidiary that was sold during the period. No authoritative reference available. false 1 BGE's portion of our total unrecognized tax benefits at December 31, 2009 and 2008 was $111.8 million and $4.8 million, respectively. 3 53 false HundredThousands UnKnown UnKnown false true