Commitments and Contingencies - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($) MGPSite Open_claim gal MW	Dec. 31, 2022 MW	Dec. 31, 2018 USD ($) MW	Dec. 31, 2017 MW
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment	$ 3,481
Accrual for Environmental Loss Contingencies, Gross	486		$ 496
Exelon Generation Co L L C [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment	2,831
Accrued Insurance, Current	14,100
Loss Contingency, Undiscounted Amount of Insurance-related Assessment Liability	450
Maximum liability per nuclear incident	13,600
Prepaid Reinsurance Premiums	335
Estimated Insurance Recoveries	3,200
Accrual for Environmental Loss Contingencies, Gross	108		108
Accrual for Environmental Loss Contingencies, Component Amount	90
Liability for Asbestos and Environmental Claims, Gross	$ 77		79
Open Asbestos Related Personal Injury Claims | Open_claim	239
Pepco Holdings LLC [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment	$ 74
Accrual for Environmental Loss Contingencies, Gross	26		27
Commonwealth Edison Co [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment	$ 257
Mgp Site Contingency Approved Cleanup Count | MGPSite	42
Mgp Site Contingency Count | MGPSite	21
Mgp Site Contingency Monitoring Count | MGPSite	21
Accrual for Environmental Loss Contingencies, Gross	$ 320		329
Potomac Electric Power Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment	48
Accrual for Environmental Loss Contingencies, Gross	24		25
PECO Energy Co [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment	$ 187
Mgp Site Contingency Approved Cleanup Count | MGPSite	26
Mgp Site Contingency Count | MGPSite	17
Mgp Site Contingency Monitoring Count | MGPSite	9
Accrual for Environmental Loss Contingencies, Gross	$ 27		27
Baltimore Gas and Electric Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment	$ 19
Mgp Site Contingency Approved Cleanup Count | MGPSite	13
Mgp Site Contingency Count | MGPSite	9
Mgp Site Contingency Monitoring Count | MGPSite	4
Accrual for Environmental Loss Contingencies, Gross	$ 5		5
Delmarva Power and Light Company [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Other Commitment	$ 16
Mgp Site Contingency Approved Cleanup Count | gal	3
Mgp Site Contingency Count | MGPSite	2
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	25
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	52
Nuclear Insurance Premiums [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Nuclear financial protection pool value	3,100
Nuclear Insurance Premiums [Member] | Maximum [Member]
Commitments And Contingencies Additional Narrative Information [Line Items]
Nuclear financial protection pool value	454
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	$ 20
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 Non-Financial Commitment | MW	27
Other Commitment	$ 97
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	$ 97
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