Related Party Transactions - Operating Revenues and Purchased Power and Fuel From Affiliates (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Related Party Transaction, Purchases from Related Party	$ (159)	$ (1,178)	$ (1,209)
Exelon Generation Co L L C [Member] | Commonwealth Edison Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	59	376	330
Exelon Generation Co L L C [Member] | PECO Energy Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	33	196	190
Exelon Generation Co L L C [Member] | Baltimore Gas And Electric Company Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	18	236	315
Exelon Generation Co L L C [Member] | Pepco Holdings LLC Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	51	366	367
Exelon Generation Co L L C [Member] | Potomac Electric Power Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	39	270	279
Exelon Generation Co L L C [Member] | Delmarva Power and Light Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	10	79	75
Exelon Generation Co L L C [Member] | Atlantic City Electric Co Affiliate [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	2	17	13
Commonwealth Edison Co [Member]
Related Party Transaction [Line Items]
Revenue from Related Parties	16	41	37
Related Party Transaction, Purchases from Related Party	$ (59)	$ (383)	$ (345)