Name:	exc_AssetRetirementObligationsLineItems
Namespace Prefix:	exc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Assumed Returns on NDT Funds

No definition available.

Name:	exc_AssumedReturnsonNDTFunds
Namespace Prefix:	exc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

The current period expense charged against earnings on decommissioning the Byron Units that are not contractually offset.

No definition available.

Name:	exc_DecommissioningRelatedActivitiesNotContractuallyOffset
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Increase (Decrease) in ARO Due to Change in DOE Spent Fuel Acceptance Date

No definition available.

Name:	exc_IncreaseDecreaseInARODueToChangeInDOESpentFuelAcceptanceDate
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Increase (Decrease) in ARO Due to Reversal of Early Retirement

No definition available.

Name:	exc_IncreaseDecreaseInARODueToReversalOfEarlyRetirement
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Increase (Decrease) in ARO Due to Updated Cost Escalation Rates and Discount Rates

No definition available.

Name:	exc_IncreaseDecreaseInARODueToUpdatedCostEscalationRatesAndDiscountRates
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Increase (Decrease) in ARO Due to Change in Retirement Timing Probabilities

No definition available.

Name:	exc_IncreaseDecreaseinARODuetoChangeinRetirementTimingProbabilities
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Increase (Decrease) in ARO Due to Early Retirement

No definition available.

Name:	exc_IncreaseDecreaseinARODuetoEarlyRetirement
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Increase (Decrease) in ARO for Impacts of Revised Decommissioning Cost Estimates

No definition available.

Name:	exc_IncreaseDecreaseinAROforImpactsofRevisedDecommissioningCostEstimates
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Number of years that measurement of the obligation at the present value of the future estimated costs and an annual average accretion of the ARO occurs.

No definition available.

Name:	exc_NumberOfYearsUsedInPresentValueMeasurement
Namespace Prefix:	exc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Historical annual average after-tax return on NDT funds

No definition available.

Name:	exc_ReturnonNuclearDecommissioningFundsHistorical
Namespace Prefix:	exc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

Amount of decommissioning shortfall with recourse for collection from customers.

No definition available.

Name:	exc_UncollectibleDecommissioningShortfall
Namespace Prefix:	exc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Percent of additional decommissioning shortfall with recourse for collection from customers.

No definition available.

Name:	exc_UncollectibleDecommissioningShortfallPercentage
Namespace Prefix:	exc_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Name:	us-gaap_AssetRetirementObligation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of increase (decrease) in asset retirement obligations.

Name:	us-gaap_AssetRetirementObligationPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

Amount of increase (decrease) in the asset retirement obligation from changes in the amount or timing of the estimated cash flows associated with the settlement of the obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 35
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6392603&loc=d3e7123-110846

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)(4)
-URI http://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849

Name:	us-gaap_AssetRetirementObligationRevisionOfEstimate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Decommission fund to pay for the costs of decontaminating and decommissioning of facilities through collection of revenues derived from utility assessments and government appropriations. Decommission fund investment for the process whereby a power station, at the end of its economic life, is taken permanently out of service and its site made available for other purposes. In the case of a nuclear station this comprises three different states of clearance. Immediately after the final closure, radioactive material such as nuclear fuel and operational waste is removed and the buildings surrounding the reactor shield are dismantled and finally the reactor itself is dismantled.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_DecommissioningFundInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of public utility's approved rate increase (decrease) by regulatory agency.

No definition available.

Name:	us-gaap_PublicUtilitiesApprovedRateIncreaseDecreaseAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Name:	srt_ConsolidatedEntitiesAxis=exc_ExelonGenerationCoLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PublicUtilityAxis=exc_NuclearDecommissioningMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PublicUtilityAxis=exc_NuclearDecommissioningByronMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PublicUtilityAxis=exc_NineMilePointMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_PublicUtilityAxis=exc_ZionStationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FairValueByAssetClassAxis=exc_NuclearDecommissioningTrustFundInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_AssetsTotalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FairValueByAssetClassAxis=us-gaap_OtherCurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: