Retirement Benefits - Defined Contribution Savings Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	$ 23	$ 24	$ 66	$ 67
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	11	9	29	27
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	3	2	9	8
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	2	4	7	8
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	4	5	11	12
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	1	1	3	3
Delmarva Power and Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	1	1	3	3
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Savings Plan Employer Contributions	$ 1	$ 1	$ 2	$ 2