Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Common Stock, Shares Authorized	2,000,000,000	2,000,000,000
Stockholders' Equity Attributable to Parent [Abstract]
Assets	$ 112,778	$ 95,384
Treasury Stock, Shares held	35,000,000
Exelon Generation Co L L C [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	$ 46,897	46,529
Commonwealth Edison Co [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	28,105	26,532
PECO Energy Co [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	10,586	10,367
Baltimore Gas and Electric Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	8,325	8,295
Potomac Electric Power Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	7,099	6,908
Delmarva Power and Light Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	3,971	3,969
Atlantic City Electric Company [Member]
Noncontrolling Interest in Variable Interest Entity	29	30
Stockholders' Equity Attributable to Parent [Abstract]
Assets	3,461	$ 3,387
Pepco Holdings LLC [Member] | Predecessor [Member]
Preferred Stock, Par or Stated Value Per Share		$ 0.01
Common Stock, Shares Authorized		400,000,000.00
Stockholders' Equity Attributable to Parent [Abstract]
Assets		$ 16,188
Common Stock, Shares, Outstanding		254,289,261.00
Common Stock, Par or Stated Value Per Share		$ 0.01
Pepco Holdings LLC [Member] | Successor [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	$ 20,921