Retirement Benefits - Allocated Portion of Pension and Postretirement Benefit Plan Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			$ 196	$ 204
Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	$ 67	$ 68	196	204
Commonwealth Edison Co
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			80	64
Commonwealth Edison Co \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	26	22	80	64
PECO Energy Co
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			13	5
PECO Energy Co \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	5	2	13	5
Baltimore Gas and Electric Company
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			21	46
Baltimore Gas and Electric Company \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	7	16	21	46
Pepco Holdings LLC
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			62	72
Pepco Holdings LLC \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	21	23	62	72
Potomac Electric Power Company
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			23	26
Potomac Electric Power Company \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	9	8	23	26
Delmarva Power and Light Company
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			11	12
Delmarva Power and Light Company \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	4	4	11	12
Atlantic City Electric Company
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs			7	10
Atlantic City Electric Company \| Pension and other post retirement benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and Other Postretirement Benefits Costs	$ 2	$ 3	$ 7	$ 10