Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2023	Jun. 30, 2022
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 25,066	$ 24,744	$ 23,491	$ 34,795	$ 24,744	$ 34,795
Other comprehensive income (loss), net of income taxes	9	(1)	12	14	8	26
Ending balance	25,079	25,066	23,656	23,491	25,079	23,656
Gains (Losses) on Cash Flow Hedges
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	8	2	0	(6)	2	(6)
OCI before reclassifications	9		0		15	0
Amounts reclassified from AOCI	0		0		0	0
Other comprehensive income (loss), net of income taxes	9		0		15	0
Ending balance	17	8	0	0	17	0
Gains (Losses) on Cash Flow Hedges | Exelon Generation Co L L C [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss), net of income taxes						6
Pension and Non-Pension Postretirement Benefit Plan Items
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(647)	(640)	(713)	(2,721)	(640)	(2,721)
OCI before reclassifications	(3)		2		(13)	2
Amounts reclassified from AOCI	3		10		6	24
Other comprehensive income (loss), net of income taxes	0		12		(7)	26
Ending balance	(647)	(647)	(701)	(713)	(647)	(701)
Pension and Non-Pension Postretirement Benefit Plan Items | Exelon Generation Co L L C [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss), net of income taxes						1,994
Foreign Currency Items
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	0	0	0	(23)	0	(23)
OCI before reclassifications	0		0		0	0
Amounts reclassified from AOCI	0		0		0	0
Other comprehensive income (loss), net of income taxes	0		0		0	0
Ending balance	0	0	0	0	0	0
Foreign Currency Items | Exelon Generation Co L L C [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss), net of income taxes						23
Total
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(639)	(638)	(713)	(2,750)	(638)	(2,750)
OCI before reclassifications	6		2		2	2
Amounts reclassified from AOCI	3		10		6	24
Other comprehensive income (loss), net of income taxes	9	(1)	12	14	8	26
Ending balance	$ (630)	$ (639)	$ (701)	$ (713)	$ (630)	(701)
Total | Exelon Generation Co L L C [Member]
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Other comprehensive income (loss), net of income taxes						$ 2,023