Variable Interest Entities - Assets and Liabilities of Consolidated VIEs (Details) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents		$ 1,182	$ 663	$ 587	$ 1,349
Restricted cash		393	438	358	247
Accounts Receivable, net
Customer		3,538	3,231
Inventories, net
Materials and supplies		1,480	1,425
Assets held for sale		13	958
Other current assets		1,380	1,647
Total current assets		13,957	12,562
Property, plant and equipment, net		84,219	82,584
Nuclear decommissioning trust funds		15,938	14,464
Other Assets, Noncurrent		2,606	3,276
Total assets	[1]	133,013	129,317
Current liabilities
Long-term debt due within one year		3,373	1,819
Accounts payable		4,136	3,562
Accrued expenses		1,955	2,078
Market-to-market derivative liabilities, current		999	295
Unamortized energy contract liabilities		91	100
Liabilities held for sale		3	375
Other current liabilities		1,064	1,264
Total current liabilities		16,111	12,771
Long-term debt		35,324	35,093
Asset retirement obligations		13,090	12,300
Unamortized energy contract liabilities		147	238
Other deferred credits and other liabilities		2,733	2,942
Total liabilities	[1]	98,218	94,449
Variable Interest Entity, Primary Beneficiary [Member]
Current assets
Cash and cash equivalents		35	98
Restricted cash		48	47
Accounts Receivable, net
Customer		24	148
Other		6	36
Inventories, net
Materials and supplies		14	244
Assets held for sale		0	101
Other current assets		405	696
Total current assets		532	1,370
Property, plant and equipment, net		2,027	5,803
Nuclear decommissioning trust funds		0	3,007
Other Assets, Noncurrent		215	301
Total noncurrent assets		2,242	9,111
Total assets		2,774	10,481
Current liabilities
Long-term debt due within one year		70	94
Accounts payable		10	81
Accrued expenses		21	70
Unamortized energy contract liabilities		0	4
Liabilities held for sale		0	16
Other current liabilities		1	5
Total current liabilities		102	270
Long-term debt		822	889
Asset retirement obligations		151	2,318
Other deferred credits and other liabilities		3	129
Total noncurrent liabilities		976	3,336
Total liabilities		1,078	3,606
Unamortized energy contract assets, current		23	22
Unamortized energy contract assets, noncurrent		202	249
AHFS - unrestricted asset		0	9
PP&E - unrestricted asset		0	1
Recourse [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Current liabilities
Total liabilities		1	8
Pepco Holdings LLC [Member]
Current assets
Cash and cash equivalents		136	111	131	124
Restricted cash		77	39	36	43
Accounts Receivable, net
Customer		512	525
Inventories, net
Materials and supplies		209	198
Other current assets		69	45
Total current assets		1,692	1,599
Property, plant and equipment, net		16,498	15,377
Other Assets, Noncurrent		258	307
Total assets	[2]	24,744	23,736
Current liabilities
Long-term debt due within one year		399	347
Accounts payable		578	539
Accrued expenses		281	299
Unamortized energy contract liabilities		89	92
Other current liabilities		171	141
Total current liabilities		2,246	2,154
Long-term debt		7,148	6,659
Asset retirement obligations		70	59
Unamortized energy contract liabilities		146	235
Other deferred credits and other liabilities		570	622
Total liabilities	[2]	14,159	13,692
Pepco Holdings LLC [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Current assets
Cash and cash equivalents		0	0
Restricted cash		0	3
Accounts Receivable, net
Customer		0	0
Other		0	0
Inventories, net
Materials and supplies		0	0
Assets held for sale		0	0
Other current assets		0	5
Total current assets		0	8
Property, plant and equipment, net		0	0
Nuclear decommissioning trust funds		0	0
Other Assets, Noncurrent		0	10
Total noncurrent assets		0	10
Total assets		0	18
Current liabilities
Long-term debt due within one year		0	26
Accounts payable		0	0
Accrued expenses		0	0
Unamortized energy contract liabilities		0	0
Liabilities held for sale		0	0
Other current liabilities		0	0
Total current liabilities		0	26
Long-term debt		0	0
Asset retirement obligations		0	0
Other deferred credits and other liabilities		0	0
Total noncurrent liabilities		0	0
Total liabilities		0	26
Atlantic City Electric Company [Member]
Current assets
Cash and cash equivalents		29	17	12	7
Restricted cash		0	3	$ 2	$ 4
Accounts Receivable, net
Customer		141	124
Inventories, net
Other current assets		3	3
Total current assets		333	326
Property, plant and equipment, net		3,729	3,475
Other Assets, Noncurrent		37	50
Total assets	[3]	4,556	4,286
Current liabilities
Long-term debt due within one year		3	261
Accounts payable		165	177
Accrued expenses		44	46
Other current liabilities		12	11
Total current liabilities		445	780
Long-term debt		1,579	1,152
Other deferred credits and other liabilities		49	48
Total liabilities	[3]	2,988	2,895
Atlantic City Electric Company [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Current assets
Cash and cash equivalents		0	0
Restricted cash		0	3
Accounts Receivable, net
Customer		0	0
Other		0	0
Inventories, net
Materials and supplies		0	0
Assets held for sale		0	0
Other current assets		0	0
Total current assets		0	3
Property, plant and equipment, net		0	0
Nuclear decommissioning trust funds		0	0
Other Assets, Noncurrent		0	10
Total noncurrent assets		0	10
Total assets		0	13
Current liabilities
Long-term debt due within one year		0	21
Accounts payable		0	0
Accrued expenses		0	0
Unamortized energy contract liabilities		0	0
Liabilities held for sale		0	0
Other current liabilities		0	0
Total current liabilities		0	21
Long-term debt		0	0
Asset retirement obligations		0	0
Other deferred credits and other liabilities		0	0
Total noncurrent liabilities		0	0
Total liabilities		$ 0	$ 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.

[2] PHI’s consolidated total assets include $0 million and $18 million as of December 31, 2021 and 2020, respectively, of PHI's consolidated VIE that can only be used to settle the liabilities of the VIE. PHI’s consolidated total liabilities include $0 million and $26 million as of December 31, 2021 and 2020, respectively, of PHI's consolidated VIE for which the VIE creditors do not have recourse to PHI. See Note 23 - Variable Interest Entities for additional information.

[3] ACE’s consolidated assets include $0 million and $13 million as of December 31, 2021 and 2020, respectively, of ACE’s consolidated VIE that can only be used to settle the liabilities of the VIE. ACE’s consolidated liabilities include $0 million and $21 million as of December 31, 2021 and 2020, respectively, of ACE’s consolidated VIE for which the VIE creditors do not have recourse to ACE. See Note 23 - Variable Interest Entities for additional information.