1.0.0.3 false CONSOLIDATED STATEMENTS OF CASH FLOWS (Constellation Energy Group, Inc. and Subsidiaries) (USD $) In Millions false 1 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 2 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 false 3 $ false false Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDPerShare Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 3 Cash Flows From Operating Activities 1 us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 4 Net income (loss) 2 us-gaap_ProfitLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 4503400000 4503.4 false false 2 true true -1318400000 -1318.4 false false 3 true true 833500000 833.5 false false No definition available. No authoritative reference available. false 5 Adjustments to reconcile to net cash provided by operating activities 2 us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 6 Depreciation, depletion, and amortization 3 us-gaap_DepreciationAndAmortization us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 589100000 589.1 false false 2 false true 583200000 583.2 false false 3 false true 557800000 557.8 false false No definition available. No authoritative reference available. false 7 Amortization of nuclear fuel 3 ceg_AmortizationOfNuclearFuel ceg false debit duration monetary The expense charged against earnings for the periodic recognition of nuclear fuel costs. false false false false false false false false false 1 false true 117900000 117.9 false false 2 false true 123900000 123.9 false false 3 false true 114300000 114.3 false false The expense charged against earnings for the periodic recognition of nuclear fuel costs. No authoritative reference available. false 8 Amortization of energy contracts and derivatives designated as hedges 3 us-gaap_AmortizationOfPowerContractsEmissionCredits us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -138400000 -138.4 false false 2 false true -256300000 -256.3 false false 3 false true -222900000 -222.9 false false No definition available. No authoritative reference available. false 9 All other amortization 3 us-gaap_OtherAmortizationOfDeferredCharges us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 135700000 135.7 false false 2 false true 40500000 40.5 false false 3 false true 11200000 11.2 false false No definition available. No authoritative reference available. false 10 Accretion of asset retirement obligations 3 us-gaap_AssetRetirementObligationAccretionExpense us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 62300000 62.3 false false 2 false true 68400000 68.4 false false 3 false true 68300000 68.3 false false No definition available. No authoritative reference available. false 11 Deferred income taxes 3 us-gaap_DeferredIncomeTaxExpenseBenefit us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1846900000 1846.9 false false 2 false true -122800000 -122.8 false false 3 false true 226200000 226.2 false false No definition available. No authoritative reference available. false 12 Investment tax credit adjustments 3 us-gaap_InvestmentTaxCredit us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -12100000 -12.1 false false 2 false true -6400000 -6.4 false false 3 false true -6700000 -6.7 false false No definition available. No authoritative reference available. false 13 Deferred fuel costs 3 us-gaap_IncreaseDecreaseInDeferredFuelCosts us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 68900000 68.9 false false 2 false true 52000000 52.0 false false 3 false true -248000000 -248.0 false false No definition available. No authoritative reference available. false 14 Defined benefit obligation expense 3 ceg_DefinedBenefitPlanExpenses ceg false debit duration monetary The amount of pension, postemployment, and other (such as medical, dental and life insurance) postretirement benefit costs... false false false false false false false false false 1 false true 85300000 85.3 false false 2 false true 99600000 99.6 false false 3 false true 111800000 111.8 false false The amount of pension, postemployment, and other (such as medical, dental and life insurance) postretirement benefit costs recognized during the period for (1) defined benefit plans (periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain or loss on assets, prior service cost or credit, transition asset or obligation, and gain or loss due to settlements or curtailments) and for (2) defined contribution plans (to the extent that a plan's defined contributions to an individual's account are to be made for periods in which that individual renders services, the net cost for a period shall be the contribution called for in that period; if a plan calls for contributions for periods after an individual retires or terminates, the estimated cost shall be accrued during the employee's service period). No authoritative reference available. false 15 Defined benefit obligation payments 3 ceg_DefinedBenefitObligationPayments ceg false credit duration monetary The amount of cash or cash equivalents contributed during the reporting period by the entity to fund its pension plans and... false false false false false false false false false 1 false true -372500000 -372.5 false false 2 false true -120400000 -120.4 false false 3 false true -165400000 -165.4 false false The amount of cash or cash equivalents contributed during the reporting period by the entity to fund its pension plans and its nonpension postretirement benefit plans as well as payments to retirees and disabled employees. No authoritative reference available. false 16 Merger termination and strategic alternatives costs 3 ceg_MergerTerminationAndStrategicAlternativesCostsCashFlowImpact ceg false debit duration monetary The cash flow impact of costs related to a merger and our pursuit of other strategic alternatives to the merger. false false false false false false false false false 1 false true 128200000 128.2 false false 2 false true 541800000 541.8 false false 3 false false 0 0 false false The cash flow impact of costs related to a merger and our pursuit of other strategic alternatives to the merger. No authoritative reference available. false 17 Workforce reduction costs 3 us-gaap_SeveranceCosts us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 12600000 12.6 false false 2 false true 22200000 22.2 false false 3 false true 2300000 2.3 false false No definition available. No authoritative reference available. false 18 Impairment losses and other costs 3 us-gaap_AssetImpairmentCharges us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 124700000 124.7 false false 2 false true 741800000 741.8 false false 3 false true 20200000 20.2 false false No definition available. No authoritative reference available. false 19 Impairment losses on nuclear decommissioning trust assets 3 ceg_ImpairmentLossesOnNuclearDecommissioningTrustAssets ceg false debit duration monetary Non-cash impairment charge on certain nuclear decommissioning trust fund assets. false false false false false false false false false 1 false true 62600000 62.6 false false 2 false true 165000000 165.0 false false 3 false true 8500000 8.5 false false Non-cash impairment charge on certain nuclear decommissioning trust fund assets. No authoritative reference available. false 20 Gain on sale of 49.99% membership interest in CENG 3 ceg_GainLossOnSaleOfInterestInCENG ceg false credit duration monetary Gain on sale of 49.99% membership interest in CENG. false false false false false false false false false 1 false true -7445600000 -7445.6 false false 2 false false 0 0 false false 3 false false 0 0 false false Gain on sale of 49.99% membership interest in CENG. No authoritative reference available. false 21 Gains on sale of CEP LLC equity 3 us-gaap_GainLossOnSaleOfStockInSubsidiaryOrEquityMethodInvestee us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false true -63300000 -63.3 false false No definition available. No authoritative reference available. false 22 Loss (gain) on divestitures 3 us-gaap_GainLossOnDispositionOfAssets us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 468800000 468.8 false false 2 false true -38100000 -38.1 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 23 Gains on termination of contracts 3 us-gaap_GainLossOnContractTermination us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false true -73100000 -73.1 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 24 Accrual of BGE residential customer credit 3 ceg_AccrualResidentialCustomerCredit ceg false debit duration monetary This element represents the accrual of residential customer credit false false false false false false false false false 1 false true 112400000 112.4 false false 2 false false 0 0 false false 3 false false 0 0 false false This element represents the accrual of residential customer credit No authoritative reference available. false 25 Equity in earnings of affiliates less than dividends received 3 us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 15500000 15.5 false false 2 false true 6300000 6.3 false false 3 false true 45300000 45.3 false false No definition available. No authoritative reference available. false 26 Derivative contracts classified as financing activities 3 ceg_DerivativeContractsClassifiedAsFinancingActivitiesOperatingActivitiesImpact ceg false debit duration monetary The amount of ongoing cash flows related to certain out-of-the-money acquired contracts that are derivatives and contain an... false false false false false false false false false 1 false true 1138300000 1138.3 false false 2 false true -107200000 -107.2 false false 3 false true 32200000 32.2 false false The amount of ongoing cash flows related to certain out-of-the-money acquired contracts that are derivatives and contain an other than insignificant financing element. As a result, the cash flows from these contracts are reclassified from cash provided by (used in) operating activities to cash provided by (used in) financing activities. No authoritative reference available. false 27 Changes in working capital 3 us-gaap_IncreaseDecreaseInOperatingCapitalAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 28 Accounts receivable, excluding margin 4 ceg_IncreaseDecreaseInAccountsReceivableExcludingMargin ceg false credit duration monetary The net change during the reporting period in amount due within one year (or one business cycle) from customers for the... false false false false false false false false false 1 false true 543300000 543.3 false false 2 false true 606700000 606.7 false false 3 false true -664200000 -664.2 false false The net change during the reporting period in amount due within one year (or one business cycle) from customers for the credit sale of goods and services and amounts related to exchange-traded derivatives, excluding margin. No authoritative reference available. false 29 Derivative assets and liabilities, excluding collateral 4 ceg_IncreaseDecreaseInDerivativeAssetsAndLiabilities ceg false credit duration monetary The net change during the reporting period of all assets and liabilities resulting from contracts that meet the criteria of... false false false false false false false false false 1 false true 425300000 425.3 false false 2 false true -757900000 -757.9 false false 3 false true -138200000 -138.2 false false The net change during the reporting period of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements, excluding collateral. No authoritative reference available. false 30 Net collateral and margin 4 us-gaap_IncreaseDecreaseInDepositOtherAssets us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 1522800000 1522.8 false false 2 false true -960300000 -960.3 false false 3 false true 49600000 49.6 false false No definition available. No authoritative reference available. false 31 Materials, supplies, and fuel stocks 4 us-gaap_IncreaseDecreaseInInventories us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 220600000 220.6 false false 2 false true -33500000 -33.5 false false 3 false true -66400000 -66.4 false false No definition available. No authoritative reference available. false 32 Other current assets 4 us-gaap_IncreaseDecreaseInOtherOperatingAssets us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 217200000 217.2 false false 2 false true -95400000 -95.4 false false 3 false true -18500000 -18.5 false false No definition available. No authoritative reference available. false 33 Accounts payable and accrued liabilities 4 us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -1105000000 -1105.0 false false 2 false true -225800000 -225.8 false false 3 false true 448800000 448.8 false false No definition available. No authoritative reference available. false 34 Liability for unrecognized tax benefits 4 us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 102100000 102.1 false false 2 false true 79700000 79.7 false false 3 false true 71900000 71.9 false false No definition available. No authoritative reference available. false 35 Other current liabilities 4 us-gaap_IncreaseDecreaseInOtherOperatingLiabilities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 788800000 788.8 false false 2 false true -238100000 -238.1 false false 3 false true -14000000 -14.0 false false No definition available. No authoritative reference available. false 36 Other 3 ceg_OtherCashAndNoncashChangesInOperatingActivities ceg false credit duration monetary Transactions that result in no cash inflows or outflows in the period in which they occur, but affect net income and thus are... false false false false false false false false false 1 false true 171700000 171.7 false false 2 false true -38500000 -38.5 false false 3 false true -53300000 -53.3 false false Transactions that result in no cash inflows or outflows in the period in which they occur, but affect net income and thus are removed when calculating net cash flow from operating activities using the indirect method combined with the net change during the reporting period in the value of other assets or liabilities used in operating activities that are not otherwise defined in the taxonomy. This element is used when there is not a more specific and appropriate element. No authoritative reference available. false 37 Net cash provided by (used in) operating activities 2 us-gaap_NetCashProvidedByUsedInOperatingActivities us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 4390800000 4390.8 false false 2 false true -1261100000 -1261.1 false false 3 false true 941000000 941.0 false false No definition available. No authoritative reference available. true 38 Cash Flows From Investing Activities 1 us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 39 Investments in property, plant and equipment 2 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -1529700000 -1529.7 false false 2 false true -1934100000 -1934.1 false false 3 false true -1295700000 -1295.7 false false No definition available. No authoritative reference available. false 40 Asset acquisitions and business combinations, net of cash acquired 2 ceg_AssetAcquisitionsAndBusinessCombinationsNetOfCashAcquired ceg false credit duration monetary The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase, and the... false false false false false false false false false 1 false true -41100000 -41.1 false false 2 false true -315300000 -315.3 false false 3 false true -347500000 -347.5 false false The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase, and the acquisition of other tangible assets not otherwise defined in the taxonomy. No authoritative reference available. false 41 Investments in nuclear decommissioning trust fund securities 2 ceg_InvestmentsInNuclearDecommissioningTrustFundSecurities ceg false credit duration monetary Cash outflows for the investment in securities within the nuclear decommissioning trust fund that are classified as cash... false false false false false false false false false 1 false true -385200000 -385.2 false false 2 false true -440600000 -440.6 false false 3 false true -659500000 -659.5 false false Cash outflows for the investment in securities within the nuclear decommissioning trust fund that are classified as cash flows from investing activities and are reported on a gross basis. No authoritative reference available. false 42 Proceeds from nuclear decommissioning trust fund securities 2 ceg_ProceedsFromNuclearDecommissioningTrustFundSecurities ceg false debit duration monetary Proceeds from the sale of securities within the nuclear decommissioning trust fund that are classified as cash flows from... false false false false false false false false false 1 false true 366500000 366.5 false false 2 false true 421900000 421.9 false false 3 false true 650700000 650.7 false false Proceeds from the sale of securities within the nuclear decommissioning trust fund that are classified as cash flows from investing activities and are reported on a gross basis. No authoritative reference available. false 43 Investments in joint ventures 2 us-gaap_PaymentsToAcquireInterestInJointVenture us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -201600000 -201.6 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 44 Issuances of loans receivable 2 ceg_IssuanceOfLoansReceivable ceg false credit duration monetary The cash outflow for the issuance of loan receivable arising from the financing of goods and services. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false true -19000000 -19.0 false false The cash outflow for the issuance of loan receivable arising from the financing of goods and services. No authoritative reference available. false 45 Proceeds from sale of 49.99% membership interest in CENG 2 ceg_ProceedsFromPaymentsForMembershipInterestSale ceg false debit duration monetary This element represents the proceeds from the sale of membership interest in joint venture. false false false false false false false false false 1 false true 3528700000 3528.7 false false 2 false false 0 0 false false 3 false false 0 0 false false This element represents the proceeds from the sale of membership interest in joint venture. No authoritative reference available. false 46 Proceeds from sales of investments and other assets 2 us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 88300000 88.3 false false 2 false true 446300000 446.3 false false 3 false true 13900000 13.9 false false No definition available. No authoritative reference available. false 47 Contract and portfolio acquisitions 2 ceg_PaymentsForContractAndPortfolioAcquistions ceg false credit duration monetary The net cash outflow for acquired energy purchase and sale agreements. These agreements had contract prices that differed... false false false false false false false false false 1 false true -2153700000 -2153.7 false false 2 false false 0 0 false false 3 false true -474200000 -474.2 false false The net cash outflow for acquired energy purchase and sale agreements. These agreements had contract prices that differed from market prices at closing, which resulted in cash payments to the counterparty at the acquisition of the agreements. No authoritative reference available. false 48 Decrease (increase) in restricted funds 2 us-gaap_IncreaseDecreaseInRestrictedCash us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 1003300000 1003.3 false false 2 false true -942800000 -942.8 false false 3 false true -109900000 -109.9 false false No definition available. No authoritative reference available. false 49 Other 2 us-gaap_PaymentsForProceedsFromOtherInvestingActivities us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 100000 0.1 false false 2 false true 21700000 21.7 false false 3 false true -45300000 -45.3 false false No definition available. No authoritative reference available. false 50 Net cash provided by (used in) investing activities 2 us-gaap_NetCashProvidedByUsedInInvestingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 675600000 675.6 false false 2 false true -2742900000 -2742.9 false false 3 false true -2286500000 -2286.5 false false No definition available. No authoritative reference available. true 51 Cash Flows From Financing Activities 1 us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 52 Net (maturity) issuance of short-term borrowings 2 us-gaap_ProceedsFromRepaymentsOfShortTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -809700000 -809.7 false false 2 false true 813700000 813.7 false false 3 false true 14000000 14.0 false false No definition available. No authoritative reference available. false 53 Proceeds from issuance of common stock 2 us-gaap_ProceedsFromIssuanceOfCommonStock us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 33900000 33.9 false false 2 false true 17600000 17.6 false false 3 false true 65100000 65.1 false false No definition available. No authoritative reference available. false 54 Proceeds from issuance of long-term debt 2 us-gaap_ProceedsFromIssuanceOfLongTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 136100000 136.1 false false 2 false true 3211400000 3211.4 false false 3 false true 698200000 698.2 false false No definition available. No authoritative reference available. false 55 Common stock dividends paid 2 us-gaap_PaymentsOfDividendsCommonStock us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -228000000 -228.0 false false 2 false true -336300000 -336.3 false false 3 false true -306000000 -306.0 false false No definition available. No authoritative reference available. false 56 Reacquisiton of common stock 2 us-gaap_PaymentsForRepurchaseOfCommonStock us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false true -16200000 -16.2 false false 3 false true -409500000 -409.5 false false No definition available. No authoritative reference available. false 57 BGE preference stock dividends paid 2 us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -13200000 -13.2 false false 2 false true -13200000 -13.2 false false 3 false true -13200000 -13.2 false false No definition available. No authoritative reference available. false 58 Proceeds from contract and portfolio acquisitions 2 ceg_ProceedsFromContractAndPortfolioAcquisitions ceg false debit duration monetary The net cash inflow for acquired energy purchase and sale agreements. These agreements had contract prices that differed from... false false false false false false false false false 1 false true 2263100000 2263.1 false false 2 false false 0 0 false false 3 false true 847800000 847.8 false false The net cash inflow for acquired energy purchase and sale agreements. These agreements had contract prices that differed from market prices at closing, which resulted in cash payments from the counterparty at the acquisition of the agreements. No authoritative reference available. false 59 Repayment of long-term debt 2 us-gaap_RepaymentsOfLongTermDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -1986800000 -1986.8 false false 2 false true -577400000 -577.4 false false 3 false true -745300000 -745.3 false false No definition available. No authoritative reference available. false 60 Derivative contracts classified as financing activities 2 ceg_DerivativeContractsClassifiedAsFinancingActivityFinancingActivitiesImpact ceg false debit duration monetary The amount of ongoing cash flows related to certain out-of-the-money acquired contracts that are derivatives and contain a... false false false false false false false false false 1 false true -1138300000 -1138.3 false false 2 false true 107200000 107.2 false false 3 false true -32200000 -32.2 false false The amount of ongoing cash flows related to certain out-of-the-money acquired contracts that are derivatives and contain a financing element. As a result, the cash flows from these contracts are reclassified from cash provided by (used in) operating activities to cash provided by (used in) financing activities. No authoritative reference available. false 61 Debt and credit facility costs 2 us-gaap_PaymentsOfDebtIssuanceCosts us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -98400000 -98.4 false false 2 false true -104800000 -104.8 false false 3 false false 0 0 false false No definition available. No authoritative reference available. false 62 Other 2 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 12700000 12.7 false false 2 false true 8300000 8.3 false false 3 false true 33400000 33.4 false false No definition available. No authoritative reference available. false 63 Net cash (used in) provided by financing activities 2 us-gaap_NetCashProvidedByUsedInFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -1828600000 -1828.6 false false 2 false true 3110300000 3110.3 false false 3 false true 152300000 152.3 false false No definition available. No authoritative reference available. true 64 Net Increase (Decrease) in Cash and Cash Equivalents 1 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 3237800000 3237.8 false false 2 false true -893700000 -893.7 false false 3 false true -1193200000 -1193.2 false false No definition available. No authoritative reference available. true 65 Cash and Cash Equivalents at Beginning of Year 1 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false true false false 1 false true 202200000 202.2 false false 2 false true 1095900000 1095.9 false false 3 false true 2289100000 2289.1 false false No definition available. No authoritative reference available. false 66 Cash and Cash Equivalents at End of Year 1 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 false true 3440000000 3440.0 false false 2 false true 202200000 202.2 false false 3 false true 1095900000 1095.9 false false No definition available. No authoritative reference available. false 68 Cash paid during the year for: 2 ceg_CashPaidDuringTheYearAbstract ceg false na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false No definition available. false 69 Interest (net of amounts capitalized) 3 us-gaap_InterestPaidNet us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 369500000 369.5 false false 2 false true 341400000 341.4 false false 3 false true 291800000 291.8 false false No definition available. No authoritative reference available. false 70 Income taxes 3 us-gaap_IncomeTaxesPaidNet us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 57100000 57.1 false false 2 true true 119200000 119.2 false false 3 true true 282400000 282.4 false false No definition available. No authoritative reference available. false false 3 67 false HundredThousands UnKnown UnKnown false true