Related Party Transactions (Schedule Of Related Party Transactions Included In Income Statement) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Delmarva Power & Light Co/De [Member]
Related Party Transaction [Line Items]
Intercompany lease transactions	$ 1	[1],[2]	$ 1	[1],[2]	$ 3	[1],[2]	$ 3	[1],[2]
Delmarva Power & Light Co/De [Member] | Conectiv Energy Supply, Inc. [Member]
Related Party Transaction [Line Items]
Amounts of transaction							1	[3]
Atlantic City Electric Co [Member]
Related Party Transaction [Line Items]
Intercompany lease transactions					(1)	[4]	(1)	[4]
Intercompany use revenue			1	[5]	1	[5]	2	[5]
Atlantic City Electric Co [Member] | Millennium Account Services LLC [Member]
Related Party Transaction [Line Items]
Amounts of transaction	$ (1)	[4]	$ (1)	[4]	$ (3)	[4]	$ (3)	[4]

[1] Included in Accounts payable due to associated companies.

[2] Included in Electric revenue.

[3] Included in Purchased energy expense.

[4] Included in Other operation and maintenance expense.

[5] Included in operating revenue.