Retirement Benefits - Contributions made to Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions			12 Months Ended
	Mar. 02, 2022	Feb. 01, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			$ 616	$ 665	$ 601
Expected qualified pension plan contributions			20
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months			48
Defined Other Postretirement Benefit Plan Estimated Future Employer Contributions In Next Fiscal Year			47
Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			184	196	148
Expected qualified pension plan contributions			20
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months			3
Defined Other Postretirement Benefit Plan Estimated Future Employer Contributions In Next Fiscal Year			19
PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			18	18	18
Expected qualified pension plan contributions			0
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months			1
Defined Other Postretirement Benefit Plan Estimated Future Employer Contributions In Next Fiscal Year			0
Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			68	81	78
Expected qualified pension plan contributions			0
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months			1
Defined Other Postretirement Benefit Plan Estimated Future Employer Contributions In Next Fiscal Year			15
Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			78	48	39
Expected qualified pension plan contributions			0
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months			9
Defined Other Postretirement Benefit Plan Estimated Future Employer Contributions In Next Fiscal Year			11
Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			11	11	11
Expected qualified pension plan contributions			0
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months			1
Defined Other Postretirement Benefit Plan Estimated Future Employer Contributions In Next Fiscal Year			11
Delmarva Power & Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			1	1	0
Expected qualified pension plan contributions			0
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months			0
Defined Other Postretirement Benefit Plan Estimated Future Employer Contributions In Next Fiscal Year			0
Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			7	3	2
Expected qualified pension plan contributions			0
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months			0
Defined Other Postretirement Benefit Plan Estimated Future Employer Contributions In Next Fiscal Year			0
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions	$ 33	$ 207	570	343	306
Pension Plan, Defined Benefit [Member] | Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			176	174	143
Pension Plan, Defined Benefit [Member] | PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			15	17	18
Pension Plan, Defined Benefit [Member] | Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			48	57	56
Pension Plan, Defined Benefit [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			69	39	30
Pension Plan, Defined Benefit [Member] | Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			3	2	2
Pension Plan, Defined Benefit [Member] | Delmarva Power & Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			1	1	0
Pension Plan, Defined Benefit [Member] | Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			7	3	2
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			42	63	40
Other Postretirement Benefit Plan, Defined Benefit [Member] | Commonwealth Edison Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			8	22	5
Other Postretirement Benefit Plan, Defined Benefit [Member] | PECO Energy Co [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			3	1	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Baltimore Gas and Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			20	24	22
Other Postretirement Benefit Plan, Defined Benefit [Member] | Pepco Holdings LLC [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			9	9	9
Other Postretirement Benefit Plan, Defined Benefit [Member] | Potomac Electric Power Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			8	9	9
Other Postretirement Benefit Plan, Defined Benefit [Member] | Delmarva Power & Light Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			0	0	0
Other Postretirement Benefit Plan, Defined Benefit [Member] | Atlantic City Electric Company [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and non-pension postretirement benefit contributions			$ 0	$ 0	$ 0