Variable Interest Entities - Summary of Significant Unconsolidated VIEs (Details) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020
Variable Interest Entity [Line Items]
Total assets	[1]	$ 133,013	$ 129,317
Total liabilities	[1]	98,218	94,449
Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		1,144	1,178
Total liabilities		296	284
Exelon's ownership interest in VIE		139	157
Other ownership interests in VIE		709	737
Commercial Agreement VIE [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		772	777
Total liabilities		80	61
Exelon's ownership interest in VIE		0	0
Other ownership interests in VIE		692	716
Equity Investment VIE [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Total assets		372	401
Total liabilities		216	223
Exelon's ownership interest in VIE		139	157
Other ownership interests in VIE		$ 17	$ 21

[1] Exelon’s consolidated assets include $2,549 million and $10,200 million as of December 31, 2021 and 2020, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $1,077 million and $3,598 million as of December 31, 2021 and 2020, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 23–Variable Interest Entities for additional information.