Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill, Gross	$ 8,660	$ 8,660
Accumulated Impairment Loss	1,983	1,983
Carrying amount	6,677	6,677
Commonwealth Edison Co [Member]
Goodwill [Line Items]
Goodwill, Gross	4,608	4,608
Accumulated Impairment Loss	1,983	1,983
Carrying amount	2,625	2,625
Pepco Holdings LLC [Member]
Goodwill [Line Items]
Goodwill, Gross	4,005	4,005
Accumulated Impairment Loss	0	0
Carrying amount	$ 4,005	$ 4,005

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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