Capacity of facility of company owned solar distribution generation facilities.

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Asset Impairments - Narrative (Details) $ in Millions	3 Months Ended		9 Months Ended
Asset Impairments - Narrative (Details) $ in Millions	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) MW	Sep. 30, 2019 USD ($)
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use			$ 567	$ 174
Net income (loss) attributable to noncontrolling interests	$ 68	$ (12)	(85)	56
Deferred income taxes and amortization of investment tax credits			164	412
Certain Distributed Energy Companies [Member]
Property, Plant and Equipment [Line Items]
Equity Method Investment, Other than Temporary Impairment		164
Net income (loss) attributable to noncontrolling interests		96
Deferred income taxes and amortization of investment tax credits		(46)
Income (Loss) from Equity Method Investments		(15)
Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use			552	174
Net income (loss) attributable to noncontrolling interests	68	(13)	(85)	56
Deferred income taxes and amortization of investment tax credits			$ (51)	$ 201
Exelon Generation Co L L C [Member] \| Certain Distributed Energy Companies [Member]
Property, Plant and Equipment [Line Items]
Equity Method Investment, Other than Temporary Impairment		164
Net income (loss) attributable to noncontrolling interests		96
Deferred income taxes and amortization of investment tax credits		(46)
Income (Loss) from Equity Method Investments		$ (15)
Antelope Valley [Member]
Property, Plant and Equipment [Line Items]
Capacity Of Facility Of Company Owned Solar Distribution Generation Facilities \| MW			242
Impairment of Long-Lived Assets Held-for-use			$ 0
Antelope Valley [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Capacity Of Facility Of Company Owned Solar Distribution Generation Facilities \| MW			242
Impairment of Long-Lived Assets Held-for-use			$ 0
Generation New England [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use	500
Generation New England [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use	$ 500
Midwest Asset Group [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use			0
Midwest Asset Group [Member] \| Exelon Generation Co L L C [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use			$ 0