Name:	exc_AccrualForEnvironmentalLossContingenciesLineItems
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The penalty assessed under a consent decree.

No definition available.

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Number of individual manufactured gas plant sites at which the respective state environmental agency has approved a cleanup plan.

No definition available.

Name:	exc_MgpSiteContingencyApprovedCleanupCount
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Data Type:	xbrli:integerItemType
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Total number of individual manufactured gas plant sites with associated possible environmental loss contingencies related to remediation.

No definition available.

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Data Type:	xbrli:integerItemType
Balance Type:	na
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Number of individual manufactured gas plant sites where monitoring or remediation activities are occurring.

No definition available.

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This represents the maximum annual retrospective premium obligation that can be assessed to each member by an industry mutual insurance company in the event of a major accidental outage at a power plant incurred by any individual members.

No definition available.

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QuantityOfMineralOilSPill

No definition available.

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Recorded amount of the accrual for a material component of an environmental loss contingency.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 5.Y.Q2)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

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Total anticipated costs associated with remediation, site restoration, postclosure, monitoring commitments, or other exit costs that may occur on the sale, disposal, or abandonment of a particular property resulting from unanticipated contamination of the assets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 5.Y.Q4)
-URI http://asc.fasb.org/extlink&oid=27011672&loc=d3e149879-122751

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13296-110859

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3602-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
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-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The total number of new claims filed pertaining to a loss contingency during the period.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

The number of real estate properties owned as of the balance sheet date.

No definition available.

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

Best estimate of the loss exposure for reasonably possible environmental contingencies at an individual site for which no accrual has been recorded.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
-Paragraph 10
-Subparagraph (c),(d)(2)
-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13237-110859

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Name:	dei_LegalEntityAxis=exc_CommonwealthEdisonCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	dei_LegalEntityAxis=exc_PecoEnergyCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	dei_LegalEntityAxis=exc_BaltimoreGasAndElectricCompanyMember
Namespace Prefix:
Data Type:	na
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Name:	dei_LegalEntityAxis=exc_ExelonGenerationCoLLCMember
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Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
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Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
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Data Type:	na
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Name:	dei_LegalEntityAxis=exc_PEPCOHoldingsIncMember
Namespace Prefix:
Data Type:	na
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Name:	dei_LegalEntityAxis=exc_PotomacElectricPowerCompanyMember
Namespace Prefix:
Data Type:	na
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Name:	dei_LegalEntityAxis=exc_DelmarvaPowerandLightCompanyMember
Namespace Prefix:
Data Type:	na
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Name:	dei_LegalEntityAxis=exc_CalpineCorporationMember
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Data Type:	na
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