Related Party Transactions - BSC and PHISCO Service Companies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Exelon Business Services Co Affiliate
Related Party Transaction [Line Items]
Related party transaction capitalized costs support services	$ 158	$ 175
Exelon Business Services Co Affiliate | Commonwealth Edison Co
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	100	83
Related party transaction capitalized costs support services	71	81
Exelon Business Services Co Affiliate | PECO Energy Co
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	58	51
Related party transaction capitalized costs support services	29	30
Exelon Business Services Co Affiliate | Baltimore Gas and Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	59	54
Related party transaction capitalized costs support services	24	24
Exelon Business Services Co Affiliate | Pepco Holdings LLC
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	50	42
Related party transaction capitalized costs support services	34	40
Exelon Business Services Co Affiliate | Potomac Electric Power Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	31	27
Related party transaction capitalized costs support services	17	14
Exelon Business Services Co Affiliate | Delmarva Power and Light Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	19	17
Related party transaction capitalized costs support services	12	10
Exelon Business Services Co Affiliate | Atlantic City Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	16	14
Related party transaction capitalized costs support services	5	14
PHI Service Co Affiliate
Related Party Transaction [Line Items]
Related party transaction capitalized costs support services	29	24
PHI Service Co Affiliate | Pepco Holdings LLC
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	0	0
Related party transaction capitalized costs support services	29	24
PHI Service Co Affiliate | Potomac Electric Power Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	33	30
Related party transaction capitalized costs support services	12	11
PHI Service Co Affiliate | Delmarva Power and Light Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	25	24
Related party transaction capitalized costs support services	9	7
PHI Service Co Affiliate | Atlantic City Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	23	22
Related party transaction capitalized costs support services	$ 8	$ 6