Related Party Transactions (Schedule Of Related Party Transactions Included In Income Statement) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Atlantic City Electric Co [Member]
Related Party Transaction [Line Items]
Intercompany use revenue	$ 3	[1]	$ 2	[1]	$ 2	[1]
Atlantic City Electric Co [Member] | Conectiv Energy [Member]
Related Party Transaction [Line Items]
Amounts of transaction					(174)	[2],[3]
Atlantic City Electric Co [Member] | Millennium Account Services LLC [Member]
Related Party Transaction [Line Items]
Amounts of transaction	(4)	[4]	(4)	[4]	(4)	[4]
Delmarva Power & Light Co/De [Member]
Related Party Transaction [Line Items]
Intercompany lease transactions (c)	4	[5]	5	[5]	7	[5]
Delmarva Power & Light Co/De [Member] | Conectiv Energy [Member]
Related Party Transaction [Line Items]
Amounts of transaction			1	[2],[6]	(103)	[2],[6]
Transcompany pipeline gas purchases with Conectiv Energy Supply, Inc. (b)(d)					$ (1)	[6],[7]

[1] Included in Operating revenue.

[2] Included in Purchased energy expense.

[3] During 2010, PHI disposed of its Conectiv Energy segment and a third party assumed Conectiv Energy Supply, Inc.'s responsibilities under those contracts.

[4] Included in Other operation and maintenance expense.

[5] Included in Electric revenue.

[6] During 2010, PHI disposed of its Conectiv Energy segment and a third party assumed Conectiv Energy Supply, Inc.'s responsibilities under these contracts.

[7] Included in Gas purchased expense.