Changes in Accumulated Other Comprehensive Income - Schedule of Changes in AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 24,744	$ 34,795
Other comprehensive income (loss), net of income taxes	(1)	14
Ending balance	25,066	23,491
Gains (Losses) on Cash Flow Hedges
Movement in Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	2	(6)
OCI before reclassifications	6
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss), net of income taxes	6	0
Ending balance	8	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	(640)	(2,721)
OCI before reclassifications	(10)
Amounts reclassified from AOCI	3	14
Other comprehensive income (loss), net of income taxes	(7)	14
Ending balance	(647)	(713)
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)
OCI before reclassifications	0
Amounts reclassified from AOCI	0	0
Other comprehensive income (loss), net of income taxes	0	0
Ending balance	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	(638)	(2,750)
OCI before reclassifications	(4)
Amounts reclassified from AOCI	3	14
Other comprehensive income (loss), net of income taxes	(1)	14
Ending balance	$ (639)	(713)
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