3.19.1 html 2154 545 1 true 210 0 false 10 false false R1.htm 0001000 - Document - Document and Entity Information Sheet http://www.exeloncorp.com/role/DocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 1001000 - Statement - Consolidated Statements of Operations and Comprehensive Income (Unaudited) Sheet http://www.exeloncorp.com/role/ConsolidatedStatementsOfOperationsAndComprehensiveIncomeUnaudited Consolidated Statements of Operations and Comprehensive Income (Unaudited) Statements 2 false false R3.htm 1002000 - Statement - Consolidated Statements of Cash Flows (Unaudited) Sheet http://www.exeloncorp.com/role/ConsolidatedStatementsOfCashFlowsUnaudited Consolidated Statements of Cash Flows (Unaudited) Statements 3 false false R4.htm 1003000 - Statement - Consolidated Balance Sheets (Unaudited) Sheet http://www.exeloncorp.com/role/ConsolidatedBalanceSheetsUnaudited Consolidated Balance Sheets (Unaudited) Statements 4 false false R5.htm 1003501 - Statement - Consolidated Balance Sheets (Unaudited) (Parenthetical) Sheet http://www.exeloncorp.com/role/ConsolidatedBalanceSheetsUnauditedParenthetical Consolidated Balance Sheets (Unaudited) (Parenthetical) Statements 5 false false R6.htm 1004000 - Statement - Consolidated Statement of Changes in Shareholders Equity (Unaudited) Sheet http://www.exeloncorp.com/role/ConsolidatedStatementOfChangesInShareholdersEquityUnaudited Consolidated Statement of Changes in Shareholders Equity (Unaudited) Statements 6 false false R7.htm 1004001 - Statement - Consolidated Statement of Changes in Shareholders Equity (Unaudited) (Parenthetical) Sheet http://www.exeloncorp.com/role/ConsolidatedStatementOfChangesInShareholdersEquityUnauditedParenthetical Consolidated Statement of Changes in Shareholders Equity (Unaudited) (Parenthetical) Statements 7 false false R8.htm 2101100 - Disclosure - Significant Accounting Policies Sheet http://www.exeloncorp.com/role/SignificantAccountingPolicies Significant Accounting Policies Notes 8 false false R9.htm 2103100 - Disclosure - Variable Interest Entities (All Registrants) Sheet http://www.exeloncorp.com/role/VariableInterestEntitiesAllRegistrants Variable Interest Entities (All Registrants) Notes 9 false false R10.htm 2104100 - Disclosure - Mergers, Acquisitions and Dispositions (Exelon and Generation) Sheet http://www.exeloncorp.com/role/MergersAcquisitionsAndDispositionsExelonAndGeneration Mergers, Acquisitions and Dispositions (Exelon and Generation) Notes 10 false false R11.htm 2105100 - Disclosure - Revenue from Contracts with Customers (All Registrants) Sheet http://www.exeloncorp.com/role/RevenueFromContractsWithCustomersAllRegistrants Revenue from Contracts with Customers (All Registrants) Notes 11 false false R12.htm 2107100 - Disclosure - Leases (All Registrants) Sheet http://www.exeloncorp.com/role/LeasesAllRegistrants Leases (All Registrants) Notes 12 false false R13.htm 2108100 - Disclosure - Regulatory Matters (All Registrants) Sheet http://www.exeloncorp.com/role/RegulatoryMattersAllRegistrants Regulatory Matters (All Registrants) Notes 13 false false R14.htm 2109100 - Disclosure - Impairment of Long-Lived Assets (Exelon and Generation) Sheet http://www.exeloncorp.com/role/ImpairmentOfLongLivedAssetsExelonAndGeneration Impairment of Long-Lived Assets (Exelon and Generation) Notes 14 false false R15.htm 2111100 - Disclosure - Early Plant Retirements (Exelon and Generation) Sheet http://www.exeloncorp.com/role/EarlyPlantRetirementsExelonAndGeneration Early Plant Retirements (Exelon and Generation) Notes 15 false false R16.htm 2112100 - Disclosure - Fair Value of Financial Assets and Liabilities (All Registrants) Sheet http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesAllRegistrants Fair Value of Financial Assets and Liabilities (All Registrants) Notes 16 false false R17.htm 2113100 - Disclosure - Derivative Financial Instruments (All Registrants) Sheet http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsAllRegistrants Derivative Financial Instruments (All Registrants) Notes 17 false false R18.htm 2114100 - Disclosure - Debt and Credit Agreements (All Registrants) Sheet http://www.exeloncorp.com/role/DebtAndCreditAgreementsAllRegistrants Debt and Credit Agreements (All Registrants) Notes 18 false false R19.htm 2115100 - Disclosure - Income Taxes (All Registrants) Sheet http://www.exeloncorp.com/role/IncomeTaxesAllRegistrants Income Taxes (All Registrants) Notes 19 false false R20.htm 2116100 - Disclosure - Nuclear Decommissioning (Exelon and Generation) Sheet http://www.exeloncorp.com/role/NuclearDecommissioningExelonAndGeneration Nuclear Decommissioning (Exelon and Generation) Notes 20 false false R21.htm 2119100 - Disclosure - Retirement Benefits (All Registrants) Sheet http://www.exeloncorp.com/role/RetirementBenefitsAllRegistrants Retirement Benefits (All Registrants) Notes 21 false false R22.htm 2121100 - Disclosure - Changes in Accumulated Other Comprehensive Income (Exelon and Generation) Sheet http://www.exeloncorp.com/role/ChangesInAccumulatedOtherComprehensiveIncomeExelonAndGeneration Changes in Accumulated Other Comprehensive Income (Exelon and Generation) Notes 22 false false R23.htm 2123100 - Disclosure - Commitments and Contingencies (All Registrants) Sheet http://www.exeloncorp.com/role/CommitmentsAndContingenciesAllRegistrants Commitments and Contingencies (All Registrants) Notes 23 false false R24.htm 2124100 - Disclosure - Supplemental Financial Information (All Registrants) Sheet http://www.exeloncorp.com/role/SupplementalFinancialInformationAllRegistrants Supplemental Financial Information (All Registrants) Notes 24 false false R25.htm 2125100 - Disclosure - Segment Information (All Registrants) Sheet http://www.exeloncorp.com/role/SegmentInformationAllRegistrants Segment Information (All Registrants) Notes 25 false false R26.htm 2201201 - Disclosure - Significant Accounting Policies (Policies) Sheet http://www.exeloncorp.com/role/SignificantAccountingPoliciesPolicies Significant Accounting Policies (Policies) Policies http://www.exeloncorp.com/role/SignificantAccountingPolicies 26 false false R27.htm 2303301 - Disclosure - Variable Interest Entities (Tables) Sheet http://www.exeloncorp.com/role/VariableInterestEntitiesTables Variable Interest Entities (Tables) Tables http://www.exeloncorp.com/role/VariableInterestEntitiesAllRegistrants 27 false false R28.htm 2305301 - Disclosure - Revenue from Contracts with Customers (Tables) Sheet http://www.exeloncorp.com/role/RevenueFromContractsWithCustomersTables Revenue from Contracts with Customers (Tables) Tables http://www.exeloncorp.com/role/RevenueFromContractsWithCustomersAllRegistrants 28 false false R29.htm 2307301 - Disclosure - Leases (Tables) Sheet http://www.exeloncorp.com/role/LeasesTables Leases (Tables) Tables http://www.exeloncorp.com/role/LeasesAllRegistrants 29 false false R30.htm 2308301 - Disclosure - Regulatory Matters (Tables) Sheet http://www.exeloncorp.com/role/RegulatoryMattersTables Regulatory Matters (Tables) Tables http://www.exeloncorp.com/role/RegulatoryMattersAllRegistrants 30 false false R31.htm 2311301 - Disclosure - Early Plant Retirements (Tables) Sheet http://www.exeloncorp.com/role/EarlyPlantRetirementsTables Early Plant Retirements (Tables) Tables http://www.exeloncorp.com/role/EarlyPlantRetirementsExelonAndGeneration 31 false false R32.htm 2312301 - Disclosure - Fair Value of Financial Assets and Liabilities (Tables) Sheet http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesTables Fair Value of Financial Assets and Liabilities (Tables) Tables http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesAllRegistrants 32 false false R33.htm 2313301 - Disclosure - Derivative Financial Instruments (Tables) Sheet http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsTables Derivative Financial Instruments (Tables) Tables http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsAllRegistrants 33 false false R34.htm 2314301 - Disclosure - Debt and Credit Agreements (Tables) Sheet http://www.exeloncorp.com/role/DebtAndCreditAgreementsTables Debt and Credit Agreements (Tables) Tables http://www.exeloncorp.com/role/DebtAndCreditAgreementsAllRegistrants 34 false false R35.htm 2315301 - Disclosure - Income Taxes (Tables) Sheet http://www.exeloncorp.com/role/IncomeTaxesTables Income Taxes (Tables) Tables http://www.exeloncorp.com/role/IncomeTaxesAllRegistrants 35 false false R36.htm 2316301 - Disclosure - Nuclear Decommissioning (Tables) Sheet http://www.exeloncorp.com/role/NuclearDecommissioningTables Nuclear Decommissioning (Tables) Tables http://www.exeloncorp.com/role/NuclearDecommissioningExelonAndGeneration 36 false false R37.htm 2319301 - Disclosure - Retirement Benefits (Tables) Sheet http://www.exeloncorp.com/role/RetirementBenefitsTables Retirement Benefits (Tables) Tables http://www.exeloncorp.com/role/RetirementBenefitsAllRegistrants 37 false false R38.htm 2321301 - Disclosure - Changes in Accumulated Other Comprehensive Income (Tables) Sheet http://www.exeloncorp.com/role/ChangesInAccumulatedOtherComprehensiveIncomeTables Changes in Accumulated Other Comprehensive Income (Tables) Tables http://www.exeloncorp.com/role/ChangesInAccumulatedOtherComprehensiveIncomeExelonAndGeneration 38 false false R39.htm 2323301 - Disclosure - Commitments and Contingencies (Tables) Sheet http://www.exeloncorp.com/role/CommitmentsAndContingenciesTables Commitments and Contingencies (Tables) Tables http://www.exeloncorp.com/role/CommitmentsAndContingenciesAllRegistrants 39 false false R40.htm 2324301 - Disclosure - Supplemental Financial Information (Tables) Sheet http://www.exeloncorp.com/role/SupplementalFinancialInformationTables Supplemental Financial Information (Tables) Tables http://www.exeloncorp.com/role/SupplementalFinancialInformationAllRegistrants 40 false false R41.htm 2325301 - Disclosure - Segment Information (Tables) Sheet http://www.exeloncorp.com/role/SegmentInformationTables Segment Information (Tables) Tables http://www.exeloncorp.com/role/SegmentInformationAllRegistrants 41 false false R42.htm 2403402 - Disclosure - Variable Interest Entities - Narrative (Details) Sheet http://www.exeloncorp.com/role/VariableInterestEntitiesNarrativeDetails Variable Interest Entities - Narrative (Details) Details 42 false false R43.htm 2403403 - Disclosure - Variable Interest Entities - Carrying Amounts and Classification of Consolidated VIE Assets and Liabilities (Details) Sheet http://www.exeloncorp.com/role/VariableInterestEntitiesCarryingAmountsAndClassificationOfConsolidatedVieAssetsAndLiabilitiesDetails Variable Interest Entities - Carrying Amounts and Classification of Consolidated VIE Assets and Liabilities (Details) Details 43 false false R44.htm 2403404 - Disclosure - Variable Interest Entities - Assets and Liabilities of VIES which Creditors or Beneficiaries have no Recourse (Details) Sheet http://www.exeloncorp.com/role/VariableInterestEntitiesAssetsAndLiabilitiesOfViesWhichCreditorsOrBeneficiariesHaveNoRecourseDetails Variable Interest Entities - Assets and Liabilities of VIES which Creditors or Beneficiaries have no Recourse (Details) Details 44 false false R45.htm 2403405 - Disclosure - Variable Interest Entities - Summary of Significant Unconsolidated VIEs (Details) Sheet http://www.exeloncorp.com/role/VariableInterestEntitiesSummaryOfSignificantUnconsolidatedViesDetails Variable Interest Entities - Summary of Significant Unconsolidated VIEs (Details) Details 45 false false R46.htm 2404401 - Disclosure - Mergers, Acquisitions and Dispositions - Narrative (Details) Sheet http://www.exeloncorp.com/role/MergersAcquisitionsAndDispositionsNarrativeDetails Mergers, Acquisitions and Dispositions - Narrative (Details) Details 46 false false R47.htm 2405402 - Disclosure - Revenue from Contracts with Customers Change in Contract with Customer, Asset and Liability (Details) Sheet http://www.exeloncorp.com/role/RevenueFromContractsWithCustomersChangeInContractWithCustomerAssetAndLiabilityDetails Revenue from Contracts with Customers Change in Contract with Customer, Asset and Liability (Details) Details 47 false false R48.htm 2405403 - Disclosure - Revenue from Contracts with Customers Performance Obligations (Details) Sheet http://www.exeloncorp.com/role/RevenueFromContractsWithCustomersPerformanceObligationsDetails Revenue from Contracts with Customers Performance Obligations (Details) Details 48 false false R49.htm 2407402 - Disclosure - Leases Lessee - Narrative (Details) Sheet http://www.exeloncorp.com/role/LeasesLesseeNarrativeDetails Leases Lessee - Narrative (Details) Details 49 false false R50.htm 2407403 - Disclosure - Leases Components of Lease Cost (Details) Sheet http://www.exeloncorp.com/role/LeasesComponentsOfLeaseCostDetails Leases Components of Lease Cost (Details) Details 50 false false R51.htm 2407404 - Disclosure - Leases Supplemental Balance Sheet Information Related to Lessee Right-of-Use Assets and Lease Liabilities (Details) Sheet http://www.exeloncorp.com/role/LeasesSupplementalBalanceSheetInformationRelatedToLesseeRightOfUseAssetsAndLeaseLiabilitiesDetails Leases Supplemental Balance Sheet Information Related to Lessee Right-of-Use Assets and Lease Liabilities (Details) Details 51 false false R52.htm 2407405 - Disclosure - Leases Lessee Future Minimum Operating Lease Maturity Payments (Details) Sheet http://www.exeloncorp.com/role/LeasesLesseeFutureMinimumOperatingLeaseMaturityPaymentsDetails Leases Lessee Future Minimum Operating Lease Maturity Payments (Details) Details 52 false false R53.htm 2407406 - Disclosure - Leases Lessee 2018 Schedule of Minimum Future Operating Lease Payments (Details) Sheet http://www.exeloncorp.com/role/LeasesLessee2018ScheduleOfMinimumFutureOperatingLeasePaymentsDetails Leases Lessee 2018 Schedule of Minimum Future Operating Lease Payments (Details) Details 53 false false R54.htm 2407407 - Disclosure - Leases Supplemental Cash Flow Information Related to Leases (Details) Sheet http://www.exeloncorp.com/role/LeasesSupplementalCashFlowInformationRelatedToLeasesDetails Leases Supplemental Cash Flow Information Related to Leases (Details) Details 54 false false R55.htm 2407408 - Disclosure - Leases Lessor - Narrative (Details) Sheet http://www.exeloncorp.com/role/LeasesLessorNarrativeDetails Leases Lessor - Narrative (Details) Details 55 false false R56.htm 2407409 - Disclosure - Leases Components of Operating Lease Income (Details) Sheet http://www.exeloncorp.com/role/LeasesComponentsOfOperatingLeaseIncomeDetails Leases Components of Operating Lease Income (Details) Details 56 false false R57.htm 2407410 - Disclosure - Leases Lessor Future Minimum Operating Lease Maturity Payments (Details) Sheet http://www.exeloncorp.com/role/LeasesLessorFutureMinimumOperatingLeaseMaturityPaymentsDetails Leases Lessor Future Minimum Operating Lease Maturity Payments (Details) Details 57 false false R58.htm 2408402 - Disclosure - Regulatory Matters - Narrative (Details) Sheet http://www.exeloncorp.com/role/RegulatoryMattersNarrativeDetails Regulatory Matters - Narrative (Details) Details 58 false false R59.htm 2408403 - Disclosure - Regulatory Matters Schedule of Completed Rate Cases (Details) (Details) Sheet http://www.exeloncorp.com/role/RegulatoryMattersScheduleOfCompletedRateCasesDetailsDetails Regulatory Matters Schedule of Completed Rate Cases (Details) (Details) Details 59 false false R60.htm 2408404 - Disclosure - Regulatory Matters Schedule of Pending Rate Cases (Details) (Details) Sheet http://www.exeloncorp.com/role/RegulatoryMattersScheduleOfPendingRateCasesDetailsDetails Regulatory Matters Schedule of Pending Rate Cases (Details) (Details) Details 60 false false R61.htm 2408405 - Disclosure - Regulatory Matters - Capitalized Ratemaking Amount Not Recognized (Details) Sheet http://www.exeloncorp.com/role/RegulatoryMattersCapitalizedRatemakingAmountNotRecognizedDetails Regulatory Matters - Capitalized Ratemaking Amount Not Recognized (Details) Details 61 false false R62.htm 2408406 - Disclosure - Regulatory Matters - Annual Electric Transmission Fillings (Details) Sheet http://www.exeloncorp.com/role/RegulatoryMattersAnnualElectricTransmissionFillingsDetails Regulatory Matters - Annual Electric Transmission Fillings (Details) Details 62 false false R63.htm 2409402 - Disclosure - Impairment of Long-Lived Assets - Narrative (Details) Sheet http://www.exeloncorp.com/role/ImpairmentOfLongLivedAssetsNarrativeDetails Impairment of Long-Lived Assets - Narrative (Details) Details 63 false false R64.htm 2411402 - Disclosure - Early Plant Retirements - Narrative (Details) Sheet http://www.exeloncorp.com/role/EarlyPlantRetirementsNarrativeDetails Early Plant Retirements - Narrative (Details) Details 64 false false R65.htm 2411403 - Disclosure - Early Plant Retirements - Pretax Expense (Details) Sheet http://www.exeloncorp.com/role/EarlyPlantRetirementsPretaxExpenseDetails Early Plant Retirements - Pretax Expense (Details) Details 65 false false R66.htm 2411404 - Disclosure - Early Plant Retirements - Implications of Potential Early Plant Retirement on Balance Sheet (Details) Sheet http://www.exeloncorp.com/role/EarlyPlantRetirementsImplicationsOfPotentialEarlyPlantRetirementOnBalanceSheetDetails Early Plant Retirements - Implications of Potential Early Plant Retirement on Balance Sheet (Details) Details 66 false false R67.htm 2412402 - Disclosure - Fair Value of Financial Assets and Liabilities - Narrative (Details) Sheet http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesNarrativeDetails Fair Value of Financial Assets and Liabilities - Narrative (Details) Details 67 false false R68.htm 2412403 - Disclosure - Fair Value of Financial Assets and Liabilities - Fair Value of Financial Liabilities Recorded at the Carrying Amount (Details) Sheet http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesFairValueOfFinancialLiabilitiesRecordedAtCarryingAmountDetails Fair Value of Financial Assets and Liabilities - Fair Value of Financial Liabilities Recorded at the Carrying Amount (Details) Details 68 false false R69.htm 2412404 - Disclosure - Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) Sheet http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesFairValueMeasurementsOfAssetsAndLiabilitiesRecurringAndNonrecurringDetails Fair Value of Financial Assets and Liabilities - Fair Value Measurements of Assets and Liabilities, Recurring and Nonrecurring (Details) Details 69 false false R70.htm 2412405 - Disclosure - Fair Value of Financial Assets and Liabilities - Fair Value Assets Liabilities Measured On Recurring Basis Unobservable Input Reconciliation (Details) Sheet http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesFairValueAssetsLiabilitiesMeasuredOnRecurringBasisUnobservableInputReconciliationDetails Fair Value of Financial Assets and Liabilities - Fair Value Assets Liabilities Measured On Recurring Basis Unobservable Input Reconciliation (Details) Details 70 false false R71.htm 2412406 - Disclosure - Fair Value of Financial Assets and Liabilities - Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings (Details) Sheet http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesFairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisGainLossIncludedInEarningsDetails Fair Value of Financial Assets and Liabilities - Fair Value Assets And Liabilities Measured On Recurring Basis Gain Loss Included In Earnings (Details) Details 71 false false R72.htm 2412407 - Disclosure - Fair Value of Financial Assets and Liabilities - Fair Value Inputs Assets Quantitative Information (Details) Sheet http://www.exeloncorp.com/role/FairValueOfFinancialAssetsAndLiabilitiesFairValueInputsAssetsQuantitativeInformationDetails Fair Value of Financial Assets and Liabilities - Fair Value Inputs Assets Quantitative Information (Details) Details 72 false false R73.htm 2413402 - Disclosure - Derivative Financial Instruments - Summary of Derivative Fair Value Balances (Details) Sheet http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsSummaryOfDerivativeFairValueBalancesDetails Derivative Financial Instruments - Summary of Derivative Fair Value Balances (Details) Details 73 false false R74.htm 2413403 - Disclosure - Derivative Financial Instruments - Summary of Economic Hedges (Details) Sheet http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsSummaryOfEconomicHedgesDetails Derivative Financial Instruments - Summary of Economic Hedges (Details) Details 74 false false R75.htm 2413404 - Disclosure - Derivative Financial Instruments - Summary of Proprietary Trading Activities (Details) Sheet http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsSummaryOfProprietaryTradingActivitiesDetails Derivative Financial Instruments - Summary of Proprietary Trading Activities (Details) Details 75 false false R76.htm 2413406 - Disclosure - Derivative Financial Instruments - Summary of Credit Risk Exposure (Details) Sheet http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsSummaryOfCreditRiskExposureDetails Derivative Financial Instruments - Summary of Credit Risk Exposure (Details) Details 76 false false R77.htm 2413407 - Disclosure - Derivative Financial Instruments - Summary of Credit Risk Related Contingent Features (Details) Sheet http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsSummaryOfCreditRiskRelatedContingentFeaturesDetails Derivative Financial Instruments - Summary of Credit Risk Related Contingent Features (Details) Details 77 false false R78.htm 2413408 - Disclosure - Derivative Financial Instruments - Narrative (Details) Sheet http://www.exeloncorp.com/role/DerivativeFinancialInstrumentsNarrativeDetails Derivative Financial Instruments - Narrative (Details) Details 78 false false R79.htm 2414402 - Disclosure - Debt and Credit Agreements - Narrative (Details) Sheet http://www.exeloncorp.com/role/DebtAndCreditAgreementsNarrativeDetails Debt and Credit Agreements - Narrative (Details) Details 79 false false R80.htm 2414403 - Disclosure - Debt and Credit Agreements - Commercial Paper Borrowings (Details) Sheet http://www.exeloncorp.com/role/DebtAndCreditAgreementsCommercialPaperBorrowingsDetails Debt and Credit Agreements - Commercial Paper Borrowings (Details) Details 80 false false R81.htm 2414404 - Disclosure - Debt and Credit Agreements - Issuance of Long-Term Debt (Details) Sheet http://www.exeloncorp.com/role/DebtAndCreditAgreementsIssuanceOfLongTermDebtDetails Debt and Credit Agreements - Issuance of Long-Term Debt (Details) Details 81 false false R82.htm 2415402 - Disclosure - Income Taxes - Narrative (Details) Sheet http://www.exeloncorp.com/role/IncomeTaxesNarrativeDetails Income Taxes - Narrative (Details) Details 82 false false R83.htm 2415403 - Disclosure - Income Taxes - Reconciliation to Effective Tax Rate (Details) Sheet http://www.exeloncorp.com/role/IncomeTaxesReconciliationToEffectiveTaxRateDetails Income Taxes - Reconciliation to Effective Tax Rate (Details) Details 83 false false R84.htm 2415404 - Disclosure - Income Taxes - Unrecognized Tax Benefits (Details) Sheet http://www.exeloncorp.com/role/IncomeTaxesUnrecognizedTaxBenefitsDetails Income Taxes - Unrecognized Tax Benefits (Details) Details 84 false false R85.htm 2416402 - Disclosure - Nuclear Decommissioning - Narrative (Details) Sheet http://www.exeloncorp.com/role/NuclearDecommissioningNarrativeDetails Nuclear Decommissioning - Narrative (Details) Details 85 false false R86.htm 2416403 - Disclosure - Nuclear Decommissioning - Rollforward of Nuclear Decommissioning ARO (Details) Sheet http://www.exeloncorp.com/role/NuclearDecommissioningRollforwardOfNuclearDecommissioningAroDetails Nuclear Decommissioning - Rollforward of Nuclear Decommissioning ARO (Details) Details 86 false false R87.htm 2419402 - Disclosure - Retirement Benefits - Narrative (Details) Sheet http://www.exeloncorp.com/role/RetirementBenefitsNarrativeDetails Retirement Benefits - Narrative (Details) Details 87 false false R88.htm 2419403 - Disclosure - Retirement Benefits - Calculation of Net Periodic Benefit Cost (Details) Sheet http://www.exeloncorp.com/role/RetirementBenefitsCalculationOfNetPeriodicBenefitCostDetails Retirement Benefits - Calculation of Net Periodic Benefit Cost (Details) Details 88 false false R89.htm 2419404 - Disclosure - Retirement Benefits - Allocated Portion of Pension and Postretirement Benefit Plan Costs (Details) Sheet http://www.exeloncorp.com/role/RetirementBenefitsAllocatedPortionOfPensionAndPostretirementBenefitPlanCostsDetails Retirement Benefits - Allocated Portion of Pension and Postretirement Benefit Plan Costs (Details) Details 89 false false R90.htm 2419405 - Disclosure - Retirement Benefits - Defined Contribution Savings Plans (Details) Sheet http://www.exeloncorp.com/role/RetirementBenefitsDefinedContributionSavingsPlansDetails Retirement Benefits - Defined Contribution Savings Plans (Details) Details 90 false false R91.htm 2421402 - Disclosure - Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) Sheet http://www.exeloncorp.com/role/ChangesInAccumulatedOtherComprehensiveIncomeScheduleOfChangesInAociDetails Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) Details 91 false false R92.htm 2421403 - Disclosure - Changes in Accumulated Other Comprehensive Income - Reclassification out of Accumulated Other Comprehensive Income (Details) Sheet http://www.exeloncorp.com/role/ChangesInAccumulatedOtherComprehensiveIncomeReclassificationOutOfAccumulatedOtherComprehensiveIncomeDetails Changes in Accumulated Other Comprehensive Income - Reclassification out of Accumulated Other Comprehensive Income (Details) Details 92 false false R93.htm 2421404 - Disclosure - Changes in Accumulated Other Comprehensive Income - Components of Other Comprehensive Income (Loss) (Details) Sheet http://www.exeloncorp.com/role/ChangesInAccumulatedOtherComprehensiveIncomeComponentsOfOtherComprehensiveIncomeLossDetails Changes in Accumulated Other Comprehensive Income - Components of Other Comprehensive Income (Loss) (Details) Details 93 false false R94.htm 2423402 - Disclosure - Commitments and Contingencies - Narrative (Details) Sheet http://www.exeloncorp.com/role/CommitmentsAndContingenciesNarrativeDetails Commitments and Contingencies - Narrative (Details) Details 94 false false R95.htm 2423403 - Disclosure - Commitments and Contingencies - Merger Commitment (Details) Sheet http://www.exeloncorp.com/role/CommitmentsAndContingenciesMergerCommitmentDetails Commitments and Contingencies - Merger Commitment (Details) Details 95 false false R96.htm 2423404 - Disclosure - Commitments and Contingencies - Schedule of Commercial Commitments (Details) Sheet http://www.exeloncorp.com/role/CommitmentsAndContingenciesScheduleOfCommercialCommitmentsDetails Commitments and Contingencies - Schedule of Commercial Commitments (Details) Details 96 false false R97.htm 2423405 - Disclosure - Commitments and Contingencies - Schedule of Accruals for Environmental Matters (Details) Sheet http://www.exeloncorp.com/role/CommitmentsAndContingenciesScheduleOfAccrualsForEnvironmentalMattersDetails Commitments and Contingencies - Schedule of Accruals for Environmental Matters (Details) Details 97 false false R98.htm 2424402 - Disclosure - Supplemental Financial Information - Operations (Detail) Sheet http://www.exeloncorp.com/role/SupplementalFinancialInformationOperationsDetail Supplemental Financial Information - Operations (Detail) Details 98 false false R99.htm 2424403 - Disclosure - Supplemental Financial Information - Utility Taxes (Details) Sheet http://www.exeloncorp.com/role/SupplementalFinancialInformationUtilityTaxesDetails Supplemental Financial Information - Utility Taxes (Details) Details 99 false false R100.htm 2424404 - Disclosure - Supplemental Financial Information - Cash Flow (Details) Sheet http://www.exeloncorp.com/role/SupplementalFinancialInformationCashFlowDetails Supplemental Financial Information - Cash Flow (Details) Details 100 false false R101.htm 2424405 - Disclosure - Supplemental Financial Information - Balance Sheet (Details) Sheet http://www.exeloncorp.com/role/SupplementalFinancialInformationBalanceSheetDetails Supplemental Financial Information - Balance Sheet (Details) Details 101 false false R102.htm 2425402 - Disclosure - Segment Information - Narrative (Details) Sheet http://www.exeloncorp.com/role/SegmentInformationNarrativeDetails Segment Information - Narrative (Details) Details 102 false false R103.htm 2425403 - Disclosure - Segment Information - Reconciliation to Consolidated Financial Statements (Details) Sheet http://www.exeloncorp.com/role/SegmentInformationReconciliationToConsolidatedFinancialStatementsDetails Segment Information - Reconciliation to Consolidated Financial Statements (Details) Details 103 false false R104.htm 2425404 - Disclosure - Segment Information - Generation Total Revenues (Details) Sheet http://www.exeloncorp.com/role/SegmentInformationGenerationTotalRevenuesDetails Segment Information - Generation Total Revenues (Details) Details 104 false false R105.htm 2425405 - Disclosure - Segment Information - Generation Total Revenues Net of Purchased Power and Fuel Expense (Details) Sheet http://www.exeloncorp.com/role/SegmentInformationGenerationTotalRevenuesNetOfPurchasedPowerAndFuelExpenseDetails Segment Information - Generation Total Revenues Net of Purchased Power and Fuel Expense (Details) Details 105 false false R106.htm 2425406 - Disclosure - Segment Information - Electric and Gas Revenue by Customer Class (Details) Sheet http://www.exeloncorp.com/role/SegmentInformationElectricAndGasRevenueByCustomerClassDetails Segment Information - Electric and Gas Revenue by Customer Class (Details) Details 106 false false All Reports Book All Reports exc-20190331.xml exc-20190331.xsd exc-20190331_cal.xml exc-20190331_def.xml exc-20190331_lab.xml exc-20190331_pre.xml http://xbrl.sec.gov/dei/2014-01-31 http://xbrl.sec.gov/invest/2013-01-31 http://xbrl.sec.gov/sic/2011-01-31 http://fasb.org/us-gaap/2017-01-31 true true