Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Amount of borrowings from a bank classified as other, maturing within one year or operating cycle, if longer.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.16)
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Debt and Credit Agreements - Narrative (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	May 23, 2018	Mar. 15, 2018	Mar. 23, 2017	Jan. 13, 2016
Corporate, Non-Segment [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable				$ 500
Debt Instrument, Interest Rate Terms	LIBOR plus 1%
Exelon Generation Co L L C [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity			$ 30
Line of Credit Facility, Maximum Borrowing Capacity			$ 95
Pepco Holdings LLC [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable					$ 500
Debt Instrument, Interest Rate Terms	LIBOR plus 1%
Atlantic City Electric Company [Member]
Debt Instrument [Line Items]
Short-term Bank Loans and Notes Payable		$ 125
Debt Instrument, Interest Rate Terms	LIBOR plus 0.55%