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Capacity of facility of company owned solar distribution generation facilities.

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Amount of gain (loss) from deconsolidation of subsidiary and derecognition of group of assets constituting transfer of business or nonprofit activity, excluding conveyance of oil and gas mineral rights and transfer of good or service in contract with customer.

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Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

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For an unclassified balance sheet, amount of receivables due from an entity that is affiliated with the reporting entity by means of direct or indirect ownership.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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The aggregate amount of write-downs for impairments recognized during the period for long-lived assets held for abandonment, exchange or sale.

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Amount classified as liabilities attributable to disposal group held for sale or disposed of, expected to be disposed of beyond one year or the normal operating cycle, if longer.

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Mergers, Acquisitions, and Dispositions - Narrative (Details) $ in Millions		3 Months Ended
	Apr. 01, 2014 USD ($)	Mar. 31, 2021 USD ($) MW	Dec. 31, 2020
Solar Business
Business Dispositions
Capacity Of Facility Of Company Owned Solar Distribution Generation Facilities \| MW		360
Disposal Group, Including Discontinued Operation, Consideration		$ 810
Proceeds from Divestiture of Businesses		675
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		125
Deconsolidation, Gain (Loss), Amount		68
Albany Green Energy biomass facility \| Minimum [Member]
Business Dispositions
Impairment of Long-Lived Assets to be Disposed of		135
Albany Green Energy biomass facility \| Maximum [Member]
Business Dispositions
Impairment of Long-Lived Assets to be Disposed of		$ 150
Exelon Generation Co L L C [Member] \| Solar Business
Business Dispositions
Capacity Of Facility Of Company Owned Solar Distribution Generation Facilities \| MW		360
Disposal Group, Including Discontinued Operation, Consideration		$ 810
Proceeds from Divestiture of Businesses		675
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		125
Deconsolidation, Gain (Loss), Amount		68
Exelon Generation Co L L C [Member] \| Albany Green Energy biomass facility \| Minimum [Member]
Business Dispositions
Impairment of Long-Lived Assets to be Disposed of		135
Exelon Generation Co L L C [Member] \| Albany Green Energy biomass facility \| Maximum [Member]
Business Dispositions
Impairment of Long-Lived Assets to be Disposed of		$ 150
CENG [Member]
Business Acquisitions
Equity Method Investment, Ownership Percentage		50.01%	50.01%
Payments of Capital Distribution	$ 400
Due from Affiliates	400	$ 632
CENG Preferred Distribution Return		8.50%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		49.99%
CENG [Member] \| Nine Mile Point
Business Acquisitions
Equity Method Investment, Ownership Percentage		82.00%
CENG [Member] \| Exelon Generation Co L L C [Member]
Business Acquisitions
Equity Method Investment, Ownership Percentage		50.01%	50.01%
Payments of Capital Distribution	400
Due from Affiliates	$ 400	$ 632
CENG Preferred Distribution Return		8.50%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		49.99%
CENG [Member] \| Exelon Generation Co L L C [Member] \| Nine Mile Point
Business Acquisitions
Equity Method Investment, Ownership Percentage		82.00%