Schedule I - Condensed Financial Information of Parent (Exelon Corporate) - Condensed Balance Sheet (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents		$ 587	$ 1,349		$ 898	$ 635
Accounts receivable, net
Other accounts receivable		1,583	1,256
Mark-to-market derivative assets, current		679	804
Regulatory assets, current		1,170	1,190
Other		1,253	1,238
Total current assets		12,037	13,328
Property, plant and equipment, net		80,233	76,707
Deferred debits and other assets
Regulatory assets, noncurrent		8,335	8,237
Other		3,197	1,575
Total assets	[1]	124,977	119,634
Current liabilities
Short-term borrowings		1,370	714
Long-term debt due within one year		4,710	1,349
Accounts payable		3,560	3,800
Accrued expenses		1,981	2,112
Payables to affiliates, current		5	5
Regulatory Liability, Current		406	644
Other		1,331	1,035
Total current liabilities		14,185	11,404
Long-term debt		31,329	34,075
Deferred credits and other liabilities
Regulatory liabilities, noncurrent		9,986	9,559
Pension obligations		4,247	3,988
Non-pension postretirement benefit obligations		2,076	1,928
Other		3,064	2,130
Total deferred credits and other liabilities		44,500	40,718
Total liabilities		90,404	86,587	[1]
Commitments and Contingencies
Shareholders’ equity
Common stock		19,274	19,116
Treasury stock, at cost		(123)	(123)
Retained earnings		16,267	14,743
Accumulated other comprehensive income (loss), net		(3,194)	(2,995)
Total shareholders’ equity		32,224	30,741
Total liabilities and equity		124,977	119,634
Exelon Corporate [Member]
Current assets
Cash and cash equivalents		1	189		$ 74	$ 18
Accounts receivable, net
Other accounts receivable		168	48
Accounts receivable from affiliates, current		41	44
Mark-to-market derivative assets, current		3	0
Note receivable from affiliates, current		679	216
Regulatory assets, current		253	182
Other		4	4
Total current assets		1,149	683
Property, plant and equipment, net		47	48
Deferred debits and other assets
Regulatory assets, noncurrent		3,772	3,742
Investments in affiliates		42,245	40,425
Deferred income taxes		1,524	1,455
Notes receivable from affiliates, noncurrent		329	898
Other		308	235
Total deferred debits and other assets		48,178	46,755
Total assets		49,374	47,486
Current liabilities
Short-term borrowings		636	500
Long-term debt due within one year		1,458	0
Accounts payable		1	1
Accrued expenses		131	184
Payables to affiliates, current		363	360
Regulatory Liability, Current		13	15
Pension obligations		77	63
Other		10	14
Total current liabilities		2,689	1,137
Long-term debt		5,717	7,147
Deferred credits and other liabilities
Regulatory liabilities, noncurrent		31	32
Pension obligations		7,960	7,795
Non-pension postretirement benefit obligations		403	199
Deferred income taxes		263	233
Other		87	202
Total deferred credits and other liabilities		8,744	8,461
Total liabilities		17,150	16,745
Commitments and Contingencies
Shareholders’ equity
Common stock		19,274	19,116
Treasury stock, at cost		(123)	(123)
Retained earnings		16,267	14,743
Accumulated other comprehensive income (loss), net		(3,194)	(2,995)
Total shareholders’ equity		32,224	30,741
Total liabilities and equity		$ 49,374	$ 47,486

[1] Exelon’s consolidated assets include $9,532 million and $9,667 million at December 31, 2019 and 2018, respectively, of certain VIEs that can only be used to settle the liabilities of the VIE. Exelon’s consolidated liabilities include $3,473 million and $3,548 million at December 31, 2019 and 2018, respectively, of certain VIEs for which the VIE creditors do not have recourse to Exelon. See Note 22–Variable Interest Entities for additional information.