Commitments and Contingencies - Narrative (Details) $ in Millions			1 Months Ended	3 Months Ended
	Apr. 07, 2026 USD ($)	Apr. 09, 2025 USD ($)	Nov. 30, 2020 USD ($)	Mar. 31, 2026 USD ($) mGPSite	Apr. 11, 2024 USD ($)	Feb. 02, 2024 USD ($)
Commitments And Contingencies Additional Narrative Information [Line Items]
Income Taxes Receivable, Noncurrent				$ 100
Commonwealth Edison Co
Commitments And Contingencies Additional Narrative Information [Line Items]
Mgp Site Contingency Monitoring Count \| mGPSite				16
Deferred Prosecution Agreement Payments			$ 200
PECO Energy Co
Commitments And Contingencies Additional Narrative Information [Line Items]
Mgp Site Contingency Monitoring Count \| mGPSite				5
Baltimore Gas and Electric Company
Commitments And Contingencies Additional Narrative Information [Line Items]
Mgp Site Contingency Monitoring Count \| mGPSite				4
Income Taxes Receivable, Noncurrent				$ 65
Delmarva Power and Light Company
Commitments And Contingencies Additional Narrative Information [Line Items]
Mgp Site Contingency Monitoring Count \| mGPSite				1
Income Taxes Receivable, Noncurrent				$ 10
Potomac Electric Power Company
Commitments And Contingencies Additional Narrative Information [Line Items]
Environmental Liability - Anacostia					$ 47
Environmental Liability - Buzzard Point						$ 10
Income Taxes Receivable, Noncurrent				25
Payments for Environmental Liabilities	$ 12	$ 12
Exelon Business Services Co Affiliate
Commitments And Contingencies Additional Narrative Information [Line Items]
Insurers' Settlement Payment				40
Settling Shareholders' Attorney Fees				10
Pepco Holdings LLC
Commitments And Contingencies Additional Narrative Information [Line Items]
Income Taxes Receivable, Noncurrent				$ 35

EXELON CORP 10-Q