Retirement Benefits - Defined Contribution Savings Plans (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	$ 26	$ 23	$ 47	$ 43
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	10	10	19	18
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	4	3	7	6
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	3	3	5	5
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	5	4	8	7
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	1	1	2	2
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	1	1	2	2
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	$ 1	$ 1	$ 1	$ 1