Related Party Transactions - BSC and PHISCO Service Companies (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Exelon Business Services Co Affiliate
Related Party Transaction [Line Items]
Related party transaction capitalized costs support services	$ 162	$ 156	$ 502	$ 500
Exelon Business Services Co Affiliate | Commonwealth Edison Co
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	92	69	263	234
Related party transaction capitalized costs support services	71	70	230	222
Exelon Business Services Co Affiliate | PECO Energy Co
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	55	44	160	140
Related party transaction capitalized costs support services	29	24	89	80
Exelon Business Services Co Affiliate | Baltimore Gas and Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	58	46	166	148
Related party transaction capitalized costs support services	23	26	69	86
Exelon Business Services Co Affiliate | Pepco Holdings LLC
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	50	39	135	135
Related party transaction capitalized costs support services	39	36	114	112
Exelon Business Services Co Affiliate | Potomac Electric Power Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	30	24	85	80
Related party transaction capitalized costs support services	13	13	41	41
Exelon Business Services Co Affiliate | Delmarva Power and Light Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	19	16	54	51
Related party transaction capitalized costs support services	12	11	32	34
Exelon Business Services Co Affiliate | Atlantic City Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	16	13	45	42
Related party transaction capitalized costs support services	13	12	39	37
PHI Service Co Affiliate
Related Party Transaction [Line Items]
Related party transaction capitalized costs support services	25	20	74	60
PHI Service Co Affiliate | Pepco Holdings LLC
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	0	0	0	0
Related party transaction capitalized costs support services	24	20	73	60
PHI Service Co Affiliate | Potomac Electric Power Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	31	28	91	86
Related party transaction capitalized costs support services	9	8	30	24
PHI Service Co Affiliate | Delmarva Power and Light Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	24	24	73	73
Related party transaction capitalized costs support services	7	7	22	20
PHI Service Co Affiliate | Atlantic City Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	23	20	67	63
Related party transaction capitalized costs support services	$ 7	$ 5	$ 20	$ 16