2.2.0.7 true Intangible Assets (Details 3) (USD $) 4052 - Disclosure - Intangible Assets (Details 3) 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 true false false false ceg_NonRegulatedBusinessMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_NonRegulatedBusinessMember dei_LegalEntityAxis explicitMember false false us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 3 USD true false false false ceg_NonRegulatedBusinessMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_NonRegulatedBusinessMember dei_LegalEntityAxis explicitMember false false us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 4 USD true false false false ceg_NonRegulatedBusinessMember dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi ceg_NonRegulatedBusinessMember dei_LegalEntityAxis explicitMember false false us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 5 USD true false false false us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 6 USD true false false false us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_ContractualRightsMember ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsByMajorClassAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ 4 Unamortized Energy Contracts. 2 ceg_FiniteLivedNetAssetsLiabilitiesIntangibleAssetsLineItems 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 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 5 Fair value of power purchase agreement with CENG 3 ceg_FairValueRelatedPartyAgreementAtClosing ceg false debit instant Fair value of power purchase agreement with CENG recorded at closing. false false false false false false false false false false false terselabel false 1 true true false false 800000000 800.0 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:monetaryItemType monetary Fair value of power purchase agreement with CENG recorded at closing. No authoritative reference available. false 6 Carrying Amount 3 ceg_UnamortizedEnergyContractNetAssetsLiabilitiesGross ceg false debit instant The gross carrying amount of the non-derivative energy contracts acquired, certain contracts which no longer qualify as... false false false false false false false false false false false terselabel false 1 false false false false 0 0     false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false -1587100000 -1587.1 true false false 6 false true false false -2332300000 -2332.3 true false false xbrli:monetaryItemType monetary The gross carrying amount of the non-derivative energy contracts acquired, certain contracts which no longer qualify as derivatives due to the absence of a liquid market, and derivatives designated as normal purchases and normal sales. No authoritative reference available. false 7 Accumulated Amortization 3 ceg_UnamortizedEnergyContractNetAssetsLiabilitiesAccumulatedAmortization ceg false credit instant The accumulated amortization related to the non-derivative energy contracts acquired, certain contracts which no longer... 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 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false 1584500000 1584.5 true false false 6 false true false false 1286800000 1286.8 true false false xbrli:monetaryItemType monetary The accumulated amortization related to the non-derivative energy contracts acquired, certain contracts which no longer qualify as derivatives due to the absence of a liquid market, and derivatives designated as normal purchases and normal sales. No authoritative reference available. false 8 Net Liability 3 ceg_UnamortizedEnergyContractNetAssetsLiabilities ceg false debit instant The net asset (liability) related to the non-derivative energy contracts acquired, certain contracts which no longer qualify... false false false false false false false false false false false totallabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false -2600000 -2.6 true false false 6 false true false false -1045500000 -1045.5 true false false xbrli:monetaryItemType monetary The net asset (liability) related to the non-derivative energy contracts acquired, certain contracts which no longer qualify as derivatives due to the absence of a liquid market, and derivatives designated as normal purchases and normal sales. No authoritative reference available. true 9 Amortization expense 3 ceg_IndefiniteLivedIntangibleAssetsAmortizationExpense ceg false debit duration Aggregate amount of amortization expense recognized for indefinite lived intangible asset during the period. 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 353100000 353.1 true false false 3 false true false false 390400000 390.4 true false false 4 false true false false 423700000 423.7 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:monetaryItemType monetary Aggregate amount of amortization expense recognized for indefinite lived intangible asset during the period. No authoritative reference available. false 10 Estimated amortization expense 3 ceg_EstimatedAmortizationExpenseAbstract 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 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 11 2010 4 ceg_FutureAmortizationExpenseIncomeYearOne ceg false debit duration Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy... 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 45600000 45.6 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:monetaryItemType monetary Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy contracts, year one. No authoritative reference available. false 12 2011 4 ceg_FutureAmortizationExpenseIncomeYearTwo ceg false debit duration Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy... 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 295100000 295.1 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:monetaryItemType monetary Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy contracts, year two. No authoritative reference available. false 13 2012 4 ceg_FutureAmortizationExpenseIncomeYearThree ceg false debit duration Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy... 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 -89800000 -89.8 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:monetaryItemType monetary Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy contracts, year three. No authoritative reference available. false 14 2013 4 ceg_FutureAmortizationExpenseIncomeYearFour ceg false debit duration Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy... 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 -92300000 -92.3 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:monetaryItemType monetary Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy contracts, year four. No authoritative reference available. false 15 2014 4 ceg_FutureAmortizationExpenseIncomeYearFive ceg false debit duration Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy... false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 true true false false -72100000 -72.1 true false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false xbrli:monetaryItemType monetary Aggregate amount of intangible asset (liability) amortization recognized as expense during the period related to energy contracts, year five. No authoritative reference available. false 6 12 false HundredThousands UnKnown UnKnown false true