Schedule I - Condensed Financial Information Of Parent Company (Investment In Consolidated Companies) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 3,654	$ 3,033
Conectiv, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	1,300	772
Potomac Electric Power Co [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	1,502	1,428
Potomac Capital Investment Corporation [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	499	498
Pepco Energy Services [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	350	331
PHI Service Company [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 3	$ 4