Organization - Additional Information (Detail) (USD $)	0 Months Ended		3 Months Ended					0 Months Ended						0 Months Ended						0 Months Ended						0 Months Ended					0 Months Ended				0 Months Ended				0 Months Ended								0 Months Ended		0 Months Ended
	Apr. 29, 2014	Apr. 02, 2014	Dec. 31, 2013	Sep. 30, 2014	Jul. 29, 2014	Apr. 29, 2014	Mar. 31, 2013	Apr. 29, 2014 Potomac Electric Power Co [Member]	Apr. 02, 2014 Potomac Electric Power Co [Member]	Sep. 30, 2014 Potomac Electric Power Co [Member]	Jul. 29, 2014 Potomac Electric Power Co [Member]	Apr. 29, 2014 Potomac Electric Power Co [Member]	Dec. 31, 2013 Potomac Electric Power Co [Member]	Apr. 29, 2014 Delmarva Power & Light Co/De [Member]	Apr. 02, 2014 Delmarva Power & Light Co/De [Member]	Sep. 30, 2014 Delmarva Power & Light Co/De [Member]	Jul. 29, 2014 Delmarva Power & Light Co/De [Member]	Apr. 29, 2014 Delmarva Power & Light Co/De [Member]	Dec. 31, 2013 Delmarva Power & Light Co/De [Member]	Apr. 29, 2014 Atlantic City Electric Co [Member]	Apr. 02, 2014 Atlantic City Electric Co [Member]	Sep. 30, 2014 Atlantic City Electric Co [Member]	Jul. 29, 2014 Atlantic City Electric Co [Member]	Apr. 29, 2014 Atlantic City Electric Co [Member]	Dec. 31, 2013 Atlantic City Electric Co [Member]	Jul. 29, 2014 Non-Voting Series A Preferred Stock [Member]	Apr. 30, 2014 Non-Voting Series A Preferred Stock [Member]	Apr. 29, 2014 Non-Voting Series A Preferred Stock [Member]	Jul. 29, 2014 Non-Voting Series A Preferred Stock [Member]	Apr. 30, 2014 Non-Voting Series A Preferred Stock [Member]	Jul. 29, 2014 Non-Voting Series A Preferred Stock [Member] Potomac Electric Power Co [Member]	Apr. 30, 2014 Non-Voting Series A Preferred Stock [Member] Potomac Electric Power Co [Member]	Apr. 29, 2014 Non-Voting Series A Preferred Stock [Member] Potomac Electric Power Co [Member]	Apr. 30, 2014 Non-Voting Series A Preferred Stock [Member] Potomac Electric Power Co [Member]	Jul. 29, 2014 Non-Voting Series A Preferred Stock [Member] Delmarva Power & Light Co/De [Member]	Apr. 30, 2014 Non-Voting Series A Preferred Stock [Member] Delmarva Power & Light Co/De [Member]	Apr. 29, 2014 Non-Voting Series A Preferred Stock [Member] Delmarva Power & Light Co/De [Member]	Apr. 30, 2014 Non-Voting Series A Preferred Stock [Member] Delmarva Power & Light Co/De [Member]	Jul. 29, 2014 Non-Voting Series A Preferred Stock [Member] Atlantic City Electric Co [Member]	Apr. 30, 2014 Non-Voting Series A Preferred Stock [Member] Atlantic City Electric Co [Member]	Apr. 29, 2014 Non-Voting Series A Preferred Stock [Member] Atlantic City Electric Co [Member]	Apr. 30, 2014 Non-Voting Series A Preferred Stock [Member] Atlantic City Electric Co [Member]	Oct. 27, 2014 Subsequent Event [Member]	Oct. 27, 2014 Subsequent Event [Member] Potomac Electric Power Co [Member]	Oct. 27, 2014 Subsequent Event [Member] Delmarva Power & Light Co/De [Member]	Oct. 27, 2014 Subsequent Event [Member] Atlantic City Electric Co [Member]	Oct. 27, 2014 Subsequent Event [Member] Non-Voting Series A Preferred Stock [Member]	Oct. 27, 2014 Subsequent Event [Member] Non-Voting Series A Preferred Stock [Member]	Oct. 27, 2014 Subsequent Event [Member] Non-Voting Series A Preferred Stock [Member] Potomac Electric Power Co [Member]	Oct. 27, 2014 Subsequent Event [Member] Non-Voting Series A Preferred Stock [Member] Delmarva Power & Light Co/De [Member]	Oct. 27, 2014 Subsequent Event [Member] Non-Voting Series A Preferred Stock [Member] Atlantic City Electric Co [Member]	Apr. 29, 2014 Maximum [Member]	Apr. 29, 2014 Maximum [Member] Potomac Electric Power Co [Member]	Apr. 29, 2014 Maximum [Member] Delmarva Power & Light Co/De [Member]	Apr. 29, 2014 Maximum [Member] Atlantic City Electric Co [Member]
Reorganization [Line Items]
Common stock, par value			$ 0.01	$ 0.01		$ 0.01				$ 0.01		$ 0.01	$ 0.01			$ 2.25		$ 0.01	$ 2.25			$ 3.00		$ 0.01	$ 3.00
Right to receive cash under cancellation of shares						$ 27.25						$ 27.25						$ 27.25						$ 27.25
Issuance of non-voting Series A Preferred Stock, shares issued																														9,000				9,000				9,000				9,000
Non-voting Series A Preferred Stock, par value																														$ 0.01				$ 0.01				$ 0.01				$ 0.01
Non-voting Series A Preferred Stock, shares purchased price																													$ 18,000,000	$ 90,000,000				$ 90,000,000				$ 90,000,000				$ 90,000,000						$ 18,000,000
Non-voting Series A Preferred Stock, maximum number of shares issued					1,800	1,800					1,800	1,800					1,800	1,800					1,800	1,800																			1,800	1,800	1,800	1,800						18,000	18,000	18,000	18,000
Amount Of Non Voting Series A Preferred Stock Purchase price																										18,000,000		18,000,000			18,000,000		18,000,000		18,000,000		18,000,000		18,000,000		18,000,000						18,000,000		18,000,000	18,000,000	18,000,000
Non-voting Series A Preferred Stock, maximum aggregate consideration						180,000,000						180,000,000						180,000,000						180,000,000
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 related expenses	40,000,000							40,000,000						40,000,000						40,000,000
Redemption of preferred stock at purchase price				$ 10,000						$ 10,000						$ 10,000						$ 10,000
PCI recorded deferred tax asset in prior years			101,000,000				101,000,000
Establishment of valuation allowances on deferred tax assets							101,000,000
Deferred tax assets valuation allowances charged off			$ 101,000,000
Non-voting Series A Preferred Stock, cumulative, non-participating cash dividend																											0.10%					0.10%				0.10%				0.10%