The net gains or losses recognized for each transaction with the acquiree that was recognized separately from the acquisition of assets and assumptions of liabilities in the business combination.

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The proportionate share of interest (percent) in a jointly owned utility plant.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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Early Plant Retirements - Narrative (Details) - USD ($) $ in Millions		12 Months Ended
	Oct. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Payments to Acquire Businesses, Gross		$ 41	$ 154	$ 208
Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Payments to Acquire Businesses, Gross		$ 41	$ 154	$ 208
Exelon Generation Co L L C [Member] \| Salem [Member] \| Nuclear Plant [Member]
Property, Plant and Equipment [Line Items]
Ownership interest		42.59%
Everett Marine Terminal [Member]
Property, Plant and Equipment [Line Items]
Payments to Acquire Businesses, Gross	$ 81
Business Combination, Separately Recognized Transactions, Net Gains and Losses	75
Everett Marine Terminal [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Payments to Acquire Businesses, Gross	81
Business Combination, Separately Recognized Transactions, Net Gains and Losses	$ 75