2.2.0.7 true Derivatives and Fair Value Measurements (Derivatives Details 6) (USD $) 4135 - Disclosure - Derivatives and Fair Value Measurements (Derivatives Details 6) 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 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 3 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 4 USD true false false false Level 1 ceg_FairValueAssetsLiabilitiesMeasuredOnNonrecurringBasisDisclosureItemsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_FairValueInputsLevel1Member ceg_FairValueAssetsLiabilitiesMeasuredOnNonrecurringBasisDisclosureItemsAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 5 USD true false false false Losses, end of period ceg_FairValueAssetsLiabilitiesMeasuredOnNonrecurringBasisDisclosureItemsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_FairValueAssetsMeasuredOnNonrecurringBasisGainsLossesMember ceg_FairValueAssetsLiabilitiesMeasuredOnNonrecurringBasisDisclosureItemsAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 6 USD true false false false Losses, end of period ceg_FairValueAssetsLiabilitiesMeasuredOnNonrecurringBasisDisclosureItemsAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_FairValueAssetsMeasuredOnNonrecurringBasisGainsLossesMember ceg_FairValueAssetsLiabilitiesMeasuredOnNonrecurringBasisDisclosureItemsAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ 3 Fair Value Assets and Liabilities Measured on Recurring Basis Unobservable Input Reconciliation Calculation 1 ceg_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationCalculationRollForward 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 xbrli:stringItemType string No definition available. false 4 Balance, Level 3 fair value measurements at beginning of period 2 ceg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetAssetLiabilityValue ceg false debit instant This element represents net assets and liabilities measured at fair value using significant unobservable inputs (Level 3)... false false false false false false false false true false false periodstartlabel false 1 true true false false 37000000 37.0 false false false 2 true true false false -147100000 -147.1 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 xbrli:monetaryItemType monetary This element represents net assets and liabilities measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. No authoritative reference available. false 5 Realized and unrealized (losses) gains recorded in income 2 ceg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetAssetLiabilityGainLossIncludedInEarnings ceg false debit duration This element represents total unrealized gains or losses for the period, arising from net assets and liabilities measured at... false false false false false false false false false false false terselabel false 1 false true false false -486900000 -486.9 false false false 2 false true false false 471200000 471.2 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 xbrli:monetaryItemType monetary This element represents total unrealized gains or losses for the period, arising from net assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value. No authoritative reference available. false 6 Realized and unrealized (losses) gains recorded in other comprehensive income 2 ceg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetAssetLiabilityGainLossIncludedInOtherComprehensiveIncome ceg false debit duration This element represents total unrealized gains or losses for the period, arising from net assets and liabilities measured at... false false false false false false false false false false false terselabel false 1 false true false false 201600000 201.6 false false false 2 false true false false -511900000 -511.9 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 xbrli:monetaryItemType monetary This element represents total unrealized gains or losses for the period, arising from net assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in other comprehensive income (a separate component of shareholders' equity). No authoritative reference available. false 7 Purchases, sales, issuances, and settlements 2 ceg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetAssetLiabilityPurchasesSalesIssuancesSettlements ceg false debit duration This element represents purchases, sales, issuances, and settlements (net) which have taken place during the period in... false false false false false false false false false false false terselabel false 1 false true false false 49100000 49.1 false false false 2 false true false false 37600000 37.6 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 xbrli:monetaryItemType monetary This element represents purchases, sales, issuances, and settlements (net) which have taken place during the period in relation to net assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3). No authoritative reference available. false 8 Net transfers into and out of Level 3 2 ceg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetAssetLiabilityTransfersNet ceg false debit duration This element represents net transfers into and out of assets and liabilities measured at fair value on a recurring basis... false false false false false false false false false false false terselabel false 1 false true false false -92300000 -92.3 false false false 2 false true false false 187200000 187.2 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 xbrli:monetaryItemType monetary This element represents net transfers into and out of assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period. No authoritative reference available. false 9 Balance, Level 3 fair value measurements at end of period 2 ceg_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetAssetLiabilityValue ceg false debit instant This element represents net assets and liabilities measured at fair value using significant unobservable inputs (Level 3)... false false false false false false false false false true false periodendlabel false 1 false true false false -291500000 -291.5 false false false 2 false true false false 37000000 37.0 false false false 3 false true false false -147100000 -147.1 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 xbrli:monetaryItemType monetary This element represents net assets and liabilities measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances. No authoritative reference available. false 10 Change in unrealized gains recorded in income relating to derivatives still held at the end of the period 2 ceg_FairValueAssetsLiabilitiesMeasuredOnRecurringBasisChangeInUnrealizedGainLossIncludedInEarnings ceg false credit duration This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included... false false false false false false false false false false false terselabel false 1 false true false false -27800000 -27.8 false false false 2 false true false false 800100000 800.1 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 xbrli:monetaryItemType monetary This item represents the amount of the total change in unrealized (holding) gains or losses for the period which are included in the statement of income. Such unrealized (holding) gains or losses relate to those assets and liabilities still held at the reporting date for which fair value is measured on a recurring basis using significant unobservable inputs (Level 3). No authoritative reference available. false 12 Fair Value Assets Liabilities 2 us-gaap_FairValueAssetsMeasuredOnNonrecurringBasisFinancialStatementCaptionsLineItems 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 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 13 Equity method investment closing price 3 us-gaap_EquityMethodInvestmentsFairValueDisclosure us-gaap true debit instant No definition available. false false false false false false false false false false false terselabel false 1 false true false false 5100000000 5100.0 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 17700000 17.7 true false false 5 false true false false 124400000 124.4 true false false 6 false false false false 0 0 true false false xbrli:monetaryItemType monetary This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investments accounted for under the equity method of accounting as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 18 -Paragraph 6 -Subparagraph b false 14 Impairment charge 3 us-gaap_AssetImpairmentCharges us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 true true false false 124700000 124.7 false false false 2 true true false false 741800000 741.8 false false false 3 true true false false 20200000 20.2 false false false 4 false false false false 0 0 true false false 5 true true false false 69700000 69.7 true false false 6 true true false false 54700000 54.7 true false false xbrli:monetaryItemType monetary The charge against earnings resulting from the aggregate write down of all assets from their carrying value to their fair value. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 144 -Paragraph 45, 46, 47 false 6 11 false HundredThousands UnKnown UnKnown false true