Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	$ 24,744	$ 34,795	$ 34,868
Other comprehensive income (loss)	(88)	89	650
Ending Balance	25,755	24,744	34,795
Cash Flow Hedges
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	2	(6)	(5)
OCI before reclassifications	(4)	2	(1)
Amounts reclassified from AOCI	(1)	0	0
Other comprehensive income (loss)	(5)	2	(1)
Ending Balance	(3)	2	(6)
Cash Flow Hedges | Exelon Generation Co L L C
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss)		6
Pension and Non-Pension Postretirement Benefit Plan Items (a)
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(640)	(2,721)	(3,372)
OCI before reclassifications	(109)	46	432
Amounts reclassified from AOCI	26	41	219
Other comprehensive income (loss)	(83)	87	651
Ending Balance	(723)	(640)	(2,721)
Pension and Non-Pension Postretirement Benefit Plan Items (a) | Exelon Generation Co L L C
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss)		1,994
Foreign Currency Items
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	0	(23)	(23)
OCI before reclassifications	0	0	0
Amounts reclassified from AOCI	0	0	0
Other comprehensive income (loss)	0	0	0
Ending Balance	0	0	(23)
Foreign Currency Items | Exelon Generation Co L L C
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss)		23
Total
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning Balance	(638)	(2,750)	(3,400)
OCI before reclassifications	(113)	48	431
Amounts reclassified from AOCI	25	41	219
Other comprehensive income (loss)	(88)	89	650
Ending Balance	$ (726)	(638)	$ (2,750)
Total | Exelon Generation Co L L C
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss)		$ 2,023