- Definition

Maximum basis points that can be added to the average rate on 30-year treasury notes, to determine the allowed ROE for ComEd's revenue requirement.

+ References

No definition available.

+ Details

Name:	exc_BasispointsforComEdsRevenueRequirement
Namespace Prefix:	exc_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency, initial revenue requirement.

+ References

No definition available.

+ Details

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

- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency, prior year annual reconciliation.

+ References

No definition available.

+ Details

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

- Definition

Line Items for Regulatory Matters Pending Rate Cases [Table]

+ References

No definition available.

+ Details

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

- Definition

Percentage of public utility's requested equity to capital, including debt and equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedEquityCapitalStructurePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of public utility's amended requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

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

- Definition

Amount of public utility's requested rate increase (decrease) with regulatory agency.

+ References

No definition available.

+ Details

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

- Definition

Percentage of public utility's requested return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=exc_Illinois2020ElectricDistributionBaseRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=exc_Maryland2020DistributionBaseRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=exc_DistrictofColumbia2019ElectricDistributionBaseRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	exc_PeriodAxis=exc_A2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	exc_PeriodAxis=exc_A2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=exc_Delaware2020GasDistributionBaseRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=exc_Delaware2020ElectricDistributionBaseRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=exc_Maryland2020ElectricDistributionBaseRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=exc_Maryland2020GasDistributionBaseRateCaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Regulatory Matters - Schedule of Pending Rate Cases (Details) (Details) - USD ($) $ in Millions	Jun. 01, 2020	May 15, 2020	Apr. 16, 2020	Mar. 17, 2020
Illinois 2020 Electric Distribution Base Rate Case [Member] \| Commonwealth Edison Co [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)			$ (11)
Public Utilities, Requested Rate Increase (Decrease), Initial Revenue Requirement, Amount			51
Public Utilities Requested Rate Increase (Decrease), Prior Year Annual Reconciliation			$ (62)
Requested Return on Equity, Percentage			8.38%
Requested Return on Distribution Rate Base, Percentage			6.28%
Basis points for ComEd's Revenue Requirement			580
Maryland 2020 Distribution Base Rate Case [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)		$ 235
Requested Return on Equity, Percentage		10.10%
District of Columbia 2019 Electric Distribution Base Rate Case [Member] \| Potomac Electric Power Company [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended	$ 136
Requested Return on Equity, Percentage	9.70%
District of Columbia 2019 Electric Distribution Base Rate Case [Member] \| Potomac Electric Power Company [Member] \| 2022 [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended	$ 73
District of Columbia 2019 Electric Distribution Base Rate Case [Member] \| Potomac Electric Power Company [Member] \| 2023 [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended	$ 63
Delaware 2020 Gas Distribution Base Rate Case [Member] \| Delmarva Power and Light Company [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended				$ 9
Requested Return on Equity, Percentage				10.30%
Delaware 2020 Electric Distribution Base Rate Case [Member] \| Delmarva Power and Light Company [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease), Amended			$ 24
Requested Return on Equity, Percentage			10.30%
Maryland 2020 Electric Distribution Base Rate Case [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)		$ 140
Maryland 2020 Gas Distribution Base Rate Case [Member] \| Baltimore Gas and Electric Company [Member]
Regulatory Matters Pending Rate Cases [Line Items]
Requested Revenue Requirement Increase (Decrease)		$ 95