Retirement Benefits - Allocated Portion of Pension and Postretirement Benefit Plan Costs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	$ 164	$ 411	$ 411
Pension and other post retirement benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	161	288	296
Commonwealth Edison Co [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	60	129	114
Commonwealth Edison Co [Member] | Pension and other post retirement benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	60	129	114
PECO Energy Co [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	(9)	8	5
PECO Energy Co [Member] | Pension and other post retirement benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	(9)	8	5
Baltimore Gas and Electric Company [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	44	61	62
Baltimore Gas and Electric Company [Member] | Pension and other post retirement benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	44	64	64
Pepco Holdings LLC [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	53	49	70
Pepco Holdings LLC [Member] | Pension and other post retirement benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	53	49	70
Potomac Electric Power Company [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	9	6	15
Potomac Electric Power Company [Member] | Pension and other post retirement benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	9	6	15
Delmarva Power & Light Company [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	3	2	7
Delmarva Power & Light Company [Member] | Pension and other post retirement benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	3	2	7
Atlantic City Electric Company [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	12	11	14
Atlantic City Electric Company [Member] | Pension and other post retirement benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Pension and non-pension postretirement benefit costs	$ 12	$ 11	$ 14