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 4 Cash Flows From Operating Activities 2 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 No definition available. false 5 Net income 3 us-gaap_ProfitLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 76000000 76.0 false false 2 true true 102300000 102.3 false false No definition available. No authoritative reference available. false 6 Adjustments to reconcile to net cash provided by operating activities 3 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 No definition available. false 7 Depreciation, depletion, and amortization 4 us-gaap_DepreciationAndAmortization us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 446800000 446.8 false false 2 false true 424500000 424.5 false false No definition available. No authoritative reference available. false 8 Amortization of nuclear fuel 4 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 102700000 102.7 false false 2 false true 91200000 91.2 false false The expense charged against earnings for the periodic recognition of nuclear fuel costs. No authoritative reference available. false 9 Amortization of energy contracts 4 us-gaap_AmortizationOfPowerContractsEmissionCredits us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -149700000 -149.7 false false 2 false true -193800000 -193.8 false false No definition available. No authoritative reference available. false 10 All other amortization 4 us-gaap_OtherAmortizationOfDeferredCharges us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 93200000 93.2 false false 2 false true 18200000 18.2 false false No definition available. No authoritative reference available. false 11 Accretion of asset retirement obligations 4 us-gaap_AssetRetirementObligationAccretionExpense us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 54600000 54.6 false false 2 false true 50800000 50.8 false false No definition available. No authoritative reference available. false 12 Deferred income taxes 4 us-gaap_DeferredIncomeTaxExpenseBenefit us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -63800000 -63.8 false false 2 false true 45000000 45.0 false false No definition available. No authoritative reference available. false 13 Investment tax credit adjustments 4 us-gaap_InvestmentTaxCredit us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -4500000 -4.5 false false 2 false true -4800000 -4.8 false false No definition available. No authoritative reference available. false 14 Deferred fuel costs 4 us-gaap_IncreaseDecreaseInDeferredFuelCosts us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 55400000 55.4 false false 2 false true 40800000 40.8 false false No definition available. No authoritative reference available. false 15 Defined benefit obligation expense 4 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 83500000 83.5 false false 2 false true 77200000 77.2 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 16 Defined benefit obligation payments 4 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 -361200000 -361.2 false false 2 false true -111400000 -111.4 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 17 Workforce reduction costs 4 us-gaap_SeveranceCosts us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 11600000 11.6 false false 2 false true 2200000 2.2 false false No definition available. No authoritative reference available. false 18 Impairment losses and other costs 4 us-gaap_AssetImpairmentCharges us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 103300000 103.3 false false 2 false true 477100000 477.1 false false No definition available. No authoritative reference available. false 19 Impairment losses on nuclear decommissioning trust assets 4 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 43600000 43.6 false false Non-cash impairment charge on certain nuclear decommissioning trust fund assets. No authoritative reference available. false 20 Merger termination and strategic alternatives costs 4 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 37200000 37.2 false false 2 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 21 Loss (gain) on divestitures 4 ceg_DisposalGroupNotDiscontinuedOperationGainLossOnDisposalCashFlowImpact ceg false credit duration monetary The cash flow impact of the gain (loss) resulting from the sale of a disposal group that is not a discontinued operation. false false false false false false false false false 1 false true 464400000 464.4 false false 2 false true -103800000 -103.8 false false The cash flow impact of the gain (loss) resulting from the sale of a disposal group that is not a discontinued operation. No authoritative reference available. false 22 Gains on termination of contracts 4 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 -81600000 -81.6 false false No definition available. No authoritative reference available. false 23 Equity in earnings of affiliates less than dividends received 4 us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 17800000 17.8 false false 2 false true 1100000 1.1 false false No definition available. No authoritative reference available. false 24 Derivative contracts classified as financing activities 4 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 1007000000 1007.0 false false 2 false true -37100000 -37.1 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 25 Changes in: 4 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 No definition available. false 26 Accounts receivable, excluding margin 5 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 754200000 754.2 false false 2 false true 221200000 221.2 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 27 Derivative assets and liabilities, excluding collateral 5 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 125000000 125.0 false false 2 false true -935000000 -935.0 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 28 Net collateral and margin 5 us-gaap_IncreaseDecreaseInDepositOtherAssets us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 1504800000 1504.8 false false 2 false true -568600000 -568.6 false false No definition available. No authoritative reference available. false 29 Materials, supplies, and fuel stocks 5 us-gaap_IncreaseDecreaseInInventories us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 239800000 239.8 false false 2 false true -328500000 -328.5 false false No definition available. No authoritative reference available. false 30 Other current assets 5 us-gaap_IncreaseDecreaseInOtherOperatingAssets us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 223900000 223.9 false false 2 false true -134700000 -134.7 false false No definition available. No authoritative reference available. false 31 Accounts payable and accrued liabilities 5 us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -1010900000 -1010.9 false false 2 false true 57200000 57.2 false false No definition available. No authoritative reference available. false 32 Liability for uncertain tax expense 5 us-gaap_UnrecognizedTaxBenefitsPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 96700000 96.7 false false 2 false false 0 0 false false No definition available. No authoritative reference available. false 33 Other current liabilities 5 us-gaap_IncreaseDecreaseInOtherOperatingLiabilities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -47900000 -47.9 false false 2 false true -173800000 -173.8 false false No definition available. No authoritative reference available. false 34 Other 4 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 53100000 53.1 false false 2 false true 6600000 6.6 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 35 Net cash provided by (used in) operating activities 3 us-gaap_NetCashProvidedByUsedInOperatingActivities us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 3975600000 3975.6 false false 2 false true -1014100000 -1014.1 false false No definition available. No authoritative reference available. true 36 Cash Flows From Investing Activities 2 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 No definition available. false 37 Investments in property, plant and equipment 3 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -1243200000 -1243.2 false false 2 false true -1360500000 -1360.5 false false No definition available. No authoritative reference available. false 38 Asset and business acquisitions, net of cash acquired 3 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 -20800000 -20.8 false false 2 false true -316500000 -316.5 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 39 Investments in nuclear decommissioning trust fund securities 3 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 -349500000 -349.5 false false 2 false true -365400000 -365.4 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 40 Proceeds from nuclear decommissioning trust fund securities 3 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 330800000 330.8 false false 2 false true 346700000 346.7 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 41 Proceeds from sales of investments and other assets 3 us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 81100000 81.1 false false 2 false true 241200000 241.2 false false No definition available. No authoritative reference available. false 42 Contract and portfolio acquisitions 3 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 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 43 Repayments of loans receivable 3 us-gaap_ProceedsFromCollectionOfLoansReceivable us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false true 26000000 26.0 false false No definition available. No authoritative reference available. false 44 Decrease in restricted funds 3 us-gaap_IncreaseDecreaseInRestrictedCash us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 979900000 979.9 false false 2 false true 8300000 8.3 false false No definition available. No authoritative reference available. false 45 Other 3 us-gaap_PaymentsForProceedsFromOtherInvestingActivities us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -15800000 -15.8 false false 2 false true -4100000 -4.1 false false No definition available. No authoritative reference available. false 46 Net cash used in investing activities 3 us-gaap_NetCashProvidedByUsedInInvestingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -2391200000 -2391.2 false false 2 false true -1424300000 -1424.3 false false No definition available. No authoritative reference available. true 47 Cash Flows From Financing Activities 2 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 No definition available. false 48 Net (repayment) issuance of short-term borrowings 3 us-gaap_ProceedsFromRepaymentsOfShortTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -520800000 -520.8 false false 2 false true 1207500000 1207.5 false false No definition available. No authoritative reference available. false 49 Proceeds from issuance of common stock 3 us-gaap_ProceedsFromIssuanceOfCommonStock us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 24400000 24.4 false false 2 false true 17600000 17.6 false false No definition available. No authoritative reference available. false 50 Proceeds from issuance of long-term debt 3 us-gaap_ProceedsFromIssuanceOfLongTermDebt us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 121100000 121.1 false false 2 false true 2100000000 2100.0 false false No definition available. No authoritative reference available. false 51 Repayment of long-term debt 3 us-gaap_RepaymentsOfLongTermDebt us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -1680600000 -1680.6 false false 2 false true -265700000 -265.7 false false No definition available. No authoritative reference available. false 52 Debt issuance costs 3 us-gaap_PaymentsOfDebtIssuanceCosts us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -67800000 -67.8 false false 2 false true -50600000 -50.6 false false No definition available. No authoritative reference available. false 53 Common stock dividends paid 3 us-gaap_PaymentsOfDividendsCommonStock us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -179600000 -179.6 false false 2 false true -250700000 -250.7 false false No definition available. No authoritative reference available. false 54 Reacquisiton of common stock 3 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 No definition available. No authoritative reference available. false 55 BGE preference stock dividends paid 3 us-gaap_PaymentsOfDividendsPreferredStockAndPreferenceStock us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -9900000 -9.9 false false 2 false true -9900000 -9.9 false false No definition available. No authoritative reference available. false 56 Proceeds from contract and portfolio acquisitions 3 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 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 57 Derivative contracts classified as financing activiites 3 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 -1007000000 -1007.0 false false 2 false true 37100000 37.1 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 58 Other 3 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 13100000 13.1 false false 2 false true 7400000 7.4 false false No definition available. No authoritative reference available. false 59 Net cash (used in) provided by financing activities 3 us-gaap_NetCashProvidedByUsedInFinancingActivities us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -1044000000 -1044.0 false false 2 false true 2776500000 2776.5 false false No definition available. No authoritative reference available. true 60 Net Increase in Cash and Cash Equivalents 2 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 540400000 540.4 false false 2 false true 338100000 338.1 false false No definition available. No authoritative reference available. true 61 Cash and Cash Equivalents at Beginning of Period 2 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 No definition available. No authoritative reference available. false 62 Cash and Cash Equivalents at End of Period 2 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant monetary No definition available. false false false false false false false true false 1 true true 742600000 742.6 false false 2 true true 1434000000 1434.0 false false No definition available. No authoritative reference available. false false 2 59 false HundredThousands UnKnown UnKnown false true