Subsequent Events - Additional Information (Detail) (USD $)									0 Months Ended										0 Months Ended		0 Months Ended		0 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Potomac Electric Power Co [Member]	Dec. 31, 2013 Potomac Electric Power Co [Member]	Mar. 31, 2014 Delmarva Power & Light Co/De [Member]	Dec. 31, 2013 Delmarva Power & Light Co/De [Member]	Mar. 31, 2014 Atlantic City Electric Co [Member]	Dec. 31, 2013 Atlantic City Electric Co [Member]	Apr. 29, 2014 Subsequent Event [Member]	Apr. 02, 2014 Subsequent Event [Member]	Apr. 29, 2014 Subsequent Event [Member] Potomac Electric Power Co [Member]	Apr. 02, 2014 Subsequent Event [Member] Potomac Electric Power Co [Member]	Apr. 29, 2014 Subsequent Event [Member] Delmarva Power & Light Co/De [Member]	Apr. 02, 2014 Subsequent Event [Member] Delmarva Power & Light Co/De [Member]	Apr. 29, 2014 Subsequent Event [Member] Atlantic City Electric Co [Member]	Apr. 02, 2014 Subsequent Event [Member] Atlantic City Electric Co [Member]	Apr. 29, 2014 Subsequent Event [Member] Non Voting Preferred Stock [Member]	Apr. 30, 2014 Subsequent Event [Member] Non Voting Preferred Stock [Member]	Apr. 29, 2014 Subsequent Event [Member] Non Voting Preferred Stock [Member] Potomac Electric Power Co [Member]	Apr. 30, 2014 Subsequent Event [Member] Non Voting Preferred Stock [Member] Potomac Electric Power Co [Member]	Apr. 29, 2014 Subsequent Event [Member] Non Voting Preferred Stock [Member] Delmarva Power & Light Co/De [Member]	Apr. 30, 2014 Subsequent Event [Member] Non Voting Preferred Stock [Member] Delmarva Power & Light Co/De [Member]	Apr. 29, 2014 Subsequent Event [Member] Non Voting Preferred Stock [Member] Atlantic City Electric Co [Member]	Apr. 30, 2014 Subsequent Event [Member] Non Voting Preferred Stock [Member] Atlantic City Electric Co [Member]	Apr. 29, 2014 Subsequent Event [Member] Maximum [Member] Non Voting Preferred Stock [Member]	Apr. 29, 2014 Subsequent Event [Member] Maximum [Member] Non Voting Preferred Stock [Member] Potomac Electric Power Co [Member]	Apr. 29, 2014 Subsequent Event [Member] Maximum [Member] Non Voting Preferred Stock [Member] Delmarva Power & Light Co/De [Member]	Apr. 29, 2014 Subsequent Event [Member] Maximum [Member] Non Voting Preferred Stock [Member] Atlantic City Electric Co [Member]
Subsequent Event [Line Items]
Common stock, par value	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 2.25	$ 2.25	$ 3.00	$ 3.00	$ 0.01		$ 0.01		$ 0.01		$ 0.01
Right to receive cash under cancellation of shares									$ 27.25		$ 27.25		$ 27.25		$ 27.25
Issuance of non voting preferred stock shares issued																		9,000		9,000		9,000		9,000
Non-voting preferred stock, par value																		$ 0.01		$ 0.01		$ 0.01		$ 0.01
Non-voting preferred stock, shares purchased price																		90,000,000		90,000,000		90,000,000		90,000,000
Non-voting Preferred Stock, maximum number of shares to be issued																	1,800		1,800		1,800		1,800		18,000	18,000	18,000	18,000
Amount Of Non Voting Preferred Stock to be Purchased Under Commitment																	18,000,000		18,000,000		18,000,000		18,000,000
Non-voting Preferred Stock, maximum aggregate consideration																	180,000,000		180,000,000		180,000,000		180,000,000
Non-voting Preferred Stock, cumulative, non-participating cash dividend																	0.10%		0.10%		0.10%		0.10%
Termination fee									259,000,000	293,000,000	259,000,000	293,000,000	259,000,000	293,000,000	259,000,000	293,000,000
Reimbursement of Termination fees									$ 40,000,000		$ 40,000,000		$ 40,000,000		$ 40,000,000