Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

Amount of expense for amortization of capitalized computer software costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128487-111756

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

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- Definition

The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128487-111756

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Property, Plant and Equipment Property, Plant and Equipment - Summary of Capitalized Software Costs (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 23, 2016	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Capitalized Software [Line Items]
Capitalized Computer Software, Net			$ 810	$ 834
Capitalized Computer Software, Amortization			282	270	$ 255
Exelon Generation Co L L C [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Net			164	173
Capitalized Computer Software, Amortization			78	73	72
Commonwealth Edison Co [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Net			206	227
Capitalized Computer Software, Amortization			79	73	62
PECO Energy Co [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Net			98	111
Capitalized Computer Software, Amortization			37	39	33
Baltimore Gas and Electric Company [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Net			166	179
Capitalized Computer Software, Amortization			48	46	44
Potomac Electric Power Company [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Net			26	2
Capitalized Computer Software, Amortization			2	0	0
Pepco Holdings LLC [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Net			165	133
Capitalized Computer Software, Amortization			33	34
Delmarva Power & Light Company [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Net			21	1
Capitalized Computer Software, Amortization			2	0	0
Atlantic City Electric Company [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Net			14	1
Capitalized Computer Software, Amortization			$ 1	$ 0	$ 0
Successor [Member] \| Pepco Holdings LLC [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Amortization		$ 29
Predecessor [Member] \| Pepco Holdings LLC [Member]
Capitalized Software [Line Items]
Capitalized Computer Software, Amortization	$ 8