Related Party Transactions (Schedule Of Related Party Transactions Included In Income Statement) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Delmarva Power & Light Co/De [Member]
Related Party Transaction [Line Items]
Intercompany lease transactions	$ 1	[1]	$ 1	[1]	$ 2	[1]	$ 2	[1]
Delmarva Power & Light Co/De [Member] | Conectiv Energy Supply, Inc. [Member]
Related Party Transaction [Line Items]
Amounts of transaction							1	[2]
Atlantic City Electric Co [Member] | Millennium Account Services LLC [Member]
Related Party Transaction [Line Items]
Amounts of transaction	$ (1)	[3]	$ (1)	[3]	$ (2)	[3]	$ (2)	[3]

[1] Included in Electric revenue.

[2] Included in Purchased energy expense.

[3] Included in Other operation and maintenance expense.