Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 23,491	$ 34,795	$ 34,313	$ 34,868	$ 34,795	$ 34,868
Other comprehensive income (loss), net of income taxes	12	14	57	54	26	111
Ending balance	23,656	23,491	34,500	34,313	23,656	34,500
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		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	(5)	(5)	0	(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	(713)	(2,721)	(3,319)	(3,372)	(2,721)	(3,372)
OCI before reclassifications	2		0		2	(2)
Amounts reclassified from AOCI	10		55		24	110
Other comprehensive income (loss), net of income taxes	12		55		26	108
Ending balance	(701)	(713)	(3,264)	(3,319)	(701)	(3,264)
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)	(22)	(23)	(23)	(23)
OCI before reclassifications	0		2		0	3
Amounts reclassified from AOCI	0		0		0	0
Other comprehensive income (loss), net of income taxes	0		2		0	3
Ending balance	0	0	(20)	(22)	0	(20)
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	(713)	(2,750)	(3,346)	(3,400)	(2,750)	(3,400)
OCI before reclassifications	2		2		2	1
Amounts reclassified from AOCI	10		55		24	110
Other comprehensive income (loss), net of income taxes	12	14	57	54	26	111
Ending balance	$ (701)	$ (713)	$ (3,289)	$ (3,346)	(701)	$ (3,289)
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