Schedule I - Condensed Financial Information Of Parent Company (Related Party Transactions) (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011
(Payable to) Receivable from Related Party, Total	$ (2)	[1]	$ (25)	[1]
Money Pool Balance with Pepco Holdings (included in cash and cash equivalents)	262		257
Potomac Capital Investment Corporation [Member]
(Payable to) Receivable from Related Party, Total			(37)	[1]
Receivable from Related Party (non-current)			154	[2]
Conectiv [Member]
(Payable to) Receivable from Related Party, Total			29	[1]
Conectiv Communication, Inc. [Member]
(Payable to) Receivable from Related Party, Total	(4)	[1]	(4)	[1]
Potomac Electric Power Co [Member]
(Payable to) Receivable from Related Party, Total			(15)	[1]
PHI Service Company [Member]
(Payable to) Receivable from Related Party, Total	1	[1]	2	[1]
Other [Member]
(Payable to) Receivable from Related Party, Total	$ 1	[1]

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

[2] Included in Notes receivable from subsidiary companies.