Retirement Benefits - Defined Contribution Savings Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	$ 22	$ 21
Commonwealth Edison Co
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	10	9
PECO Energy Co
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	3	3
Baltimore Gas and Electric Company
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	3	2
Pepco Holdings LLC
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	2	3
Potomac Electric Power Company
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	1	1
Delmarva Power and Light Company
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	1	1
Atlantic City Electric Company
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	$ 0	$ 0