Name:	exc_ExpectedGenerationHedgedInNextTwelveMonths
Namespace Prefix:	exc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Incremental collateral amount required to be provided related to its financial instruments, including derivatives, non-derivatives, normal purchase normal sales contracts and applicable payables and receivables, if the credit rating is downgraded below investment grade.

No definition available.

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

- References

No definition available.

Name:	exc_NonRecourseDebtHedgePercentage
Namespace Prefix:	exc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Non Recourse Debt Interest Rate Swap

No definition available.

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

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Nominal or face amount used to calculate payment on derivative.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5579245-113959

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

Energy volume that must be purchased within the specified time period of the agreement to avoid penalties or unfavorable effects on pricing, among other adverse consequences.

No definition available.

Name:	us-gaap_LongTermPurchaseCommitmentMinimumEnergyVolumeRequired
Namespace Prefix:	us-gaap_
Data Type:	num:energyItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_DebtInstrumentAxis=exc_ExGenRenewablesIVDec2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_LongtermDebtTypeAxis=exc_NonRecourseDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NotDesignatedAsHedgingInstrumentEconomicHedgeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

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

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeContractMember
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:	dei_LegalEntityAxis=exc_CommonwealthEdisonCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=exc_PecoEnergyCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	dei_LegalEntityAxis=exc_BaltimoreGasAndElectricCompanyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: