Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 23,656	$ 23,491	$ 34,795	$ 34,500	$ 34,313	$ 34,868	$ 34,795	$ 34,868
Other comprehensive income (loss), net of income taxes	9	12	14	66	57	54	35	177
Ending balance	24,582	23,656	23,491	34,259	34,500	34,313	24,582	34,259
Gains (Losses) on Cash Flow Hedges
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	0		(6)	(5)		(5)	(6)	(5)
OCI before reclassifications				0			0	(1)
Amounts reclassified from AOCI	0			0			0	0
Other comprehensive income (loss), net of income taxes	0			0			0	(1)
Ending balance	0	0		(6)	(5)		0	(6)
Gains (Losses) on Cash Flow Hedges | Total
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Ending balance				(5)				(5)
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	(701)		(2,721)	(3,264)		(3,372)	(2,721)	(3,372)
OCI before reclassifications				14			2	15
Amounts reclassified from AOCI	9			55			33	163
Other comprehensive income (loss), net of income taxes	9			69			35	178
Ending balance	(692)	(701)		(3,194)	(3,264)		(692)	(3,194)
Pension and Non-Pension Postretirement Benefit Plan Items | Total
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Ending balance				(3,195)				(3,195)
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		(23)	(20)		(23)	(23)	(23)
OCI before reclassifications				(3)			0	0
Amounts reclassified from AOCI	0			0			0	0
Other comprehensive income (loss), net of income taxes	0			(3)			0	0
Ending balance	0	0		(23)	(20)		0	(23)
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	(701)	(713)	(2,750)	(3,289)	(3,346)	(3,400)	(2,750)	(3,400)
OCI before reclassifications				11			2	14
Amounts reclassified from AOCI	9			55			33	163
Other comprehensive income (loss), net of income taxes	9	12	14	66	57	54	35	177
Ending balance	$ (692)	$ (701)	$ (713)	$ (3,223)	$ (3,289)	$ (3,346)	(692)	$ (3,223)
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