Regulatory Matters Regulatory Matters - Schedule of Pending Rate Cases (Details) - USD ($) $ in Millions								12 Months Ended
		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%

[1] {F|ahBzfndlYmZpbGluZ3MtaHJkcmoLEgZYTUxEb2MiXlhCUkxEb2NHZW5JbmZvOmVlYzRiNDIxOTkxNDRkN2ViNWYzYTRhOTVmMjFkNDYzfFRleHRTZWxlY3Rpb246NUYyM0EwMDI1MDhGQUUyMUZEMzExNTNGOUY0NjExNDUM}