Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Common Stock, Shares Authorized		2,000,000,000	2,000,000,000
Stockholders' Equity Attributable to Parent [Abstract]
Assets		$ 114,535	$ 95,384
Treasury Stock, Shares held		35,000,000
Exelon Generation Co L L C [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		$ 47,568	46,529
Commonwealth Edison Co [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		28,020	26,532
PECO Energy Co [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		11,041	10,367
Baltimore Gas and Electric Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets	[1]	8,857	8,295
Potomac Electric Power Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		7,219	6,908
Delmarva Power and Light Company [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		4,023	3,969
Atlantic City Electric Company [Member]
Noncontrolling Interest in Variable Interest Entity		34	30
Stockholders' Equity Attributable to Parent [Abstract]
Assets		3,507	$ 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
Stockholders' Equity Attributable to Parent [Abstract]
Assets			$ 16,188
Common Stock, Shares, Outstanding			254,289,261
Common Stock, Par or Stated Value Per Share			$ 0.01
Pepco Holdings LLC [Member] | Successor [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Assets		$ 21,063

[1] BGE’s consolidated assets include $47 million and $26 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE that can only be used to settle the liabilities of the VIE. BGE’s consolidated liabilities include $83 million and $122 million at September 30, 2016 and December 31, 2015, respectively, of BGE’s consolidated VIE for which the VIE creditors do not have recourse to BGE. See Note 3 - Variable Interest Entities.