Commitments and Contingencies - Narrative (Details) $ in Millions		3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 23, 2016 USD ($) MW	Mar. 31, 2021 USD ($) MGPSite Open_claim MW	Mar. 31, 2020 MW	Sep. 30, 2018 MW	Dec. 31, 2022 MW	Dec. 31, 2020 USD ($)
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 3,123
Accrual for Environmental Loss Contingencies, Gross		473				$ 483
Liability for Asbestos and Environmental Claims, Gross		88				89
Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		2,555
Accrual for Environmental Loss Contingencies, Gross		119				121
Liability for Asbestos and Environmental Claims, Gross		88				89
Exelon Generation Co L L C [Member] | LDC Damages
Commitments And Contingencies Additional Narrative Information [Line Items]
LDC Damages		40
Exelon Generation Co L L C [Member] | LDC Damages - Accrued Liability
Commitments And Contingencies Additional Narrative Information [Line Items]
LDC Damages		40
Commonwealth Edison Co [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 224
Mgp Site Contingency Monitoring Count | MGPSite		21
Accrual for Environmental Loss Contingencies, Gross		$ 281				293
Deferred Prosecution Agreement Payments						200
PECO Energy Co [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 180
Mgp Site Contingency Monitoring Count | MGPSite		8
Accrual for Environmental Loss Contingencies, Gross		$ 23				23
Baltimore Gas and Electric Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 6
Mgp Site Contingency Monitoring Count | MGPSite		4
Accrual for Environmental Loss Contingencies, Gross		$ 6				2
Pepco Holdings LLC [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		52
Accrual for Environmental Loss Contingencies, Gross		44				44
Potomac Electric Power Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		24
Accrual for Environmental Loss Contingencies, Gross		42				42
Delmarva Power and Light Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 17
Mgp Site Contingency Count | MGPSite		1
Accrual for Environmental Loss Contingencies, Gross		$ 1				$ 1
Open Claims [Member] | Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Liability for Asbestos and Environmental Claims, Gross		$ 24
Open Asbestos Related Personal Injury Claims | Open_claim		243
Estimated Future Claims [Member] | Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Liability for Asbestos and Environmental Claims, Gross		$ 64
Pepco Holdings Inc [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		513
Pepco Holdings Inc [Member] | Pepco Holdings LLC [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		320
Pepco Holdings Inc [Member] | Potomac Electric Power Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		120
Pepco Holdings Inc [Member] | Delmarva Power and Light Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		89
West Lake [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Accrual for Environmental Loss Contingencies, Gross		280
West Lake [Member] | Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Accrual for Environmental Loss Contingencies, Gross		30
Accrual for Environmental Loss Contingencies, Component Amount		90
Other Solar Projects [Member] | Pepco Holdings Inc [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Business Acquisition, Expected New Generation Mwh | MW	37
Other Commitment	$ 135	$ 121
Other Non-Financial Commitment | MW		27
Other Solar Projects [Member] | Pepco Holdings Inc [Member] | Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment		$ 121
Wind Assets [Member] | Pepco Holdings Inc [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Non-Financial Commitment | MW	100
Wind Assets [Member] | Pepco Holdings Inc [Member] | Delmarva Power and Light Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Purchase Commitment | MW	120		40	40
Subsequent Event [Member] | Wind Assets [Member] | Pepco Holdings Inc [Member] | Delmarva Power and Light Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Purchase Commitment | MW					40