Regulatory Matters - Energy Efficiency Formula Rate (Details) - Commonwealth Edison Co [Member] - ComEd 2022 Energy Efficiency Formula Rate [Domain] - USD ($) $ in Millions	Oct. 27, 2022	May 25, 2022
Schedule of Energy Efficiency Formula Rate Updates [Line Items]
Public Utilities, Requested Rate Increase (Decrease), Amount		$ 50
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 50
Public Utilities, Approved Return on Equity, Percentage	7.85%
Public Utilities, Requested Equity Capital Structure, Percentage	5.94%
Basis points for ComEd's Revenue Requirement	580
2021
Schedule of Energy Efficiency Formula Rate Updates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ (16)
Public Utilities, Approved Return on Equity, Percentage	6.99%
Public Utilities, Approved Equity Capital Structure, Percentage	5.52%
2023
Schedule of Energy Efficiency Formula Rate Updates [Line Items]
Public Utilities, Approved Rate Increase (Decrease), Amount	$ 66

- 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

[Line Items] for Schedule of Energy Efficiency Formula Rate Updates [Table]

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedEquityCapitalStructurePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Percentage of public utility's approved return on equity.

+ References

No definition available.

+ Details

Name:	us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
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:	dtr-types:percentItemType
Balance Type:	na
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

- Details

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

- Details

Name:	us-gaap_PublicUtilitiesRegulatoryProceedingAxis=exc_ComEd2022EnergyEfficiencyFormulaRateDomain
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	exc_PeriodAxis=exc_A2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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