Commitments And Contingencies (General Litigation) (Details) (Potomac Electric Power Co [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012 plaintiff lawsuit
Potomac Electric Power Co [Member]
Loss Contingencies [Line Items]
Number of plaintiffs	448
Compensatory damages sought per plaintiff	$ 2
Punitive damages sought per plaintiff	4
Cases still pending against Pepco	90
Monetary damages sought in the remaining suits	$ 360

The total amount of pending claims pertaining to a loss contingency accrual as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant