Commitments and Contingencies - Narrative (Details) $ in Millions	1 Months Ended
	Nov. 30, 2020 USD ($)	Mar. 31, 2024 USD ($) mGPSite
Commonwealth Edison Co
Commitments And Contingencies Additional Narrative Information [Line Items]
Mgp Site Contingency Monitoring Count | mGPSite		16
Deferred Prosecution Agreement Payments	$ 200.0
Loss Contingency Accrual		$ 46.2
Customer Refund Liability, Current		38.0
Commonwealth Edison Co | Illinois Chamber of Commerce
Commitments And Contingencies Additional Narrative Information [Line Items]
Customer Refund Liability, Current		$ 31.0
PECO Energy Co
Commitments And Contingencies Additional Narrative Information [Line Items]
Mgp Site Contingency Monitoring Count | mGPSite		6
Baltimore Gas and Electric Company
Commitments And Contingencies Additional Narrative Information [Line Items]
Mgp Site Contingency Monitoring Count | mGPSite		4
Delmarva Power and Light Company
Commitments And Contingencies Additional Narrative Information [Line Items]
Mgp Site Contingency Monitoring Count | mGPSite		1
Potomac Electric Power Company
Commitments And Contingencies Additional Narrative Information [Line Items]
Environmental Liability - Anacostia		$ 47.0
Environmental Liability - Buzzard Point		10.0
Exelon Business Services Co Affiliate
Commitments And Contingencies Additional Narrative Information [Line Items]
Deferred Prosecution Agreement Liability, Current		173.0
Insurers' Settlement Payment		40.0
Settling Shareholders' Attorney Fees		$ 10.0