Related Party Transactions - BSC and PHISCO Service Companies (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Exelon Business Services Co Affiliate
Related Party Transaction [Line Items]
Related party transaction capitalized costs support services	$ 162	$ 159	$ 323	$ 317
Exelon Business Services Co Affiliate \| Commonwealth Edison Co
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	100	104	200	204
Related party transaction capitalized costs support services	61	63	124	134
Exelon Business Services Co Affiliate \| PECO Energy Co
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	61	61	120	119
Related party transaction capitalized costs support services	28	29	54	58
Exelon Business Services Co Affiliate \| Baltimore Gas and Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	63	62	125	121
Related party transaction capitalized costs support services	32	25	65	49
Exelon Business Services Co Affiliate \| Pepco Holdings LLC
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	49	49	100	99
Related party transaction capitalized costs support services	41	42	80	76
Exelon Business Services Co Affiliate \| Potomac Electric Power Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	32	32	63	63
Related party transaction capitalized costs support services	17	18	34	35
Exelon Business Services Co Affiliate \| Delmarva Power and Light Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	20	20	40	39
Related party transaction capitalized costs support services	12	13	24	25
Exelon Business Services Co Affiliate \| Atlantic City Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	16	16	32	32
Related party transaction capitalized costs support services	9	10	18	15
PHI Service Co Affiliate
Related Party Transaction [Line Items]
Related party transaction capitalized costs support services	29	29	53	58
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	29	29	53	58
PHI Service Co Affiliate \| Potomac Electric Power Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	32	33	62	66
Related party transaction capitalized costs support services	12	12	23	24
PHI Service Co Affiliate \| Delmarva Power and Light Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	26	26	50	51
Related party transaction capitalized costs support services	9	8	16	17
PHI Service Co Affiliate \| Atlantic City Electric Company
Related Party Transaction [Line Items]
Operating and maintenance from affiliates	24	25	47	48
Related party transaction capitalized costs support services	$ 8	$ 9	$ 14	$ 17