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Regulatory Matters Regulatory Matters - Schedule of Pending Rate Cases (Details) - USD ($) $ in Millions |  |  |  |  |  |  | 12 Months Ended
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Jan. 15, 2019 | Nov. 19, 2018 | Aug. 21, 2018 | May 31, 2018 | Apr. 17, 2018 | Dec. 19, 2017 | Dec. 31, 2018
Atlantic City Electric Company [Member] |  |  |  |  |  |  |  |
Regulatory Matters Pending Rate Cases [Line Items] |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  | $ 40 |  |  |  | $ 4
Atlantic City Electric Company [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |
Regulatory Matters Pending Rate Cases [Line Items] |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount | [1] |  | $ 122 |  |  |  |  |
Public Utilities, Requested Return on Equity, Percentage |  |  |  | 10.10% |  |  |  |
Potomac Electric Power Company [Member] |  |  |  |  |  |  |  |
Regulatory Matters Pending Rate Cases [Line Items] |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  |  |  |  |  |  |  | $ 6
Potomac Electric Power Company [Member] | Electric Distribution [Member] |  |  |  |  |  |  |  |
Regulatory Matters Pending Rate Cases [Line Items] |  |  |  |  |  |  |  |
Public Utilities, Requested Rate Increase (Decrease), Amount |  | $ 30 |  |  |  |  | $ 66 |
Public Utilities, Requested Return on Equity, Percentage |  | 10.30% |  |  | 9.50% | 9.525% |  |
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- Definition Line Items for Regulatory Matters Pending Rate Cases [Table] + References No definition available. + Details
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- Definition Amount of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
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