Shareholders' Equity Schedule of Common Stock Authorized and Outstanding (Details) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Common stock, shares authorized	2,000,000,000	2,000,000,000
Common Stock [Member]
Class of Stock [Line Items]
Common stock, shares authorized	2,000,000,000	2,000,000,000
Common Stock, Shares, Outstanding	963,335,888	924,035,059
Common Stock [Member] | Commonwealth Edison Co [Member]
Class of Stock [Line Items]
Common Stock, Par or Stated Value Per Share	$ 12.50	$ 12.50
Common stock, shares authorized	250,000,000	250,000,000
Common Stock, Shares, Outstanding	127,021,246	127,017,157
Common Stock [Member] | PECO Energy Co [Member]
Class of Stock [Line Items]
Common stock, shares authorized	500,000,000	500,000,000
Common Stock, Shares, Outstanding	170,478,507	170,478,507
Common Stock [Member] | Baltimore Gas and Electric Company [Member]
Class of Stock [Line Items]
Common stock, shares authorized	1,500	1,500
Common Stock, Shares, Outstanding	1,000	1,000
Common Stock [Member] | Potomac Electric Power Company [Member]
Class of Stock [Line Items]
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common Stock, Shares, Outstanding	100	100
Common Stock [Member] | Delmarva Power and Light Company [Member]
Class of Stock [Line Items]
Common Stock, Par or Stated Value Per Share	$ 2.25	$ 2.25
Common stock, shares authorized	1,000	1,000
Common Stock, Shares, Outstanding	1,000	1,000
Common Stock [Member] | Atlantic City Electric Company [Member]
Class of Stock [Line Items]
Common Stock, Par or Stated Value Per Share	$ 3.00	$ 3.00
Common stock, shares authorized	25,000,000	25,000,000
Common Stock, Shares, Outstanding	8,546,017	8,546,017