Discontinued Operations and Disposal Groups (Details) - Income Statement - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Discontinued Operations - Income Statement
Revenue from Related Parties	$ 6	$ 7
Operating and maintenance	1,178	1,083
Cost, Depreciation and Amortization	817	757
Taxes, Miscellaneous	354	317
Costs and Expenses	4,427	3,808
Other, net	137	58
Nonoperating Income (Expense)	(201)	(260)
Income taxes	218	39
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	117	(789)
Net income (loss) attributable to noncontrolling interests	1	25
Net Income (Loss) from Discontinued Operations Available to Common Shareholders, Basic	116	(814)
Total transaction and transition costs incurred related to the Separation	52	3
Total transaction costs relating to the Separation	19
Exelon Generation Co L L C [Member]
Discontinued Operations - Income Statement
Revenue from Contract with Customer, Including Assessed Tax	1,855	5,265
Revenue from Related Parties	161	294
Disposal Group, Including Discontinued Operation, Revenue	2,016	5,559
Purchased power and/or fuel	1,138	4,610
Operating and maintenance	371	904
Cost, Depreciation and Amortization	94	940
Taxes, Miscellaneous	44	121
Costs and Expenses	1,647	6,575
Gain (Loss) on Disposition of Assets	10	71
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	379	(945)
Disposal Group, Including Discontinued Operation, Interest Expense	(20)	(68)
Other, net	(281)	167
Nonoperating Income (Expense)	(301)	99
Discontinued Operation, Income (Loss) from Discontinued Operation, before Income Tax	78	(846)
Income taxes	(40)	(58)
Income (Loss) from Equity Method Investments	(1)	(1)
Income (Loss) from Discontinued Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	117	(789)
Net income (loss) attributable to noncontrolling interests	1	25
Net Income (Loss) from Discontinued Operations Available to Common Shareholders, Basic	116	(814)
Total transition costs relating to the Separation	2	1
Total transaction costs relating to the Separation	$ 50	$ 2