Commitments And Contingencies (General Litigation) (Details) (Pepco [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2011
Pepco [Member]
Number of plaintiffs	448
Compensatory damages	$ 2
Punitive damages	4
Cases successfully dismissed with prejudice	400
Cases still pending against Pepco	180
Cases filed	90
Monetary damages sought in the remaining suits	$ 360

Compensatory Damages

Name:	pom_CompensatoryDamages
Namespace Prefix:	pom
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Monetary damages sought

+ Details

Name:	pom_MonetaryDamagesSought
Namespace Prefix:	pom
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number Of Plaintiffs

+ Details

Name:	pom_NumberOfPlaintiffs
Namespace Prefix:	pom
Data Type:	xbrli:positiveIntegerItemType
Balance Type:	na
Period Type:	duration

- Definition

Punitive Damages

+ Details

Name:	pom_PunitiveDamages
Namespace Prefix:	pom
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of claims settled and dismissed during the period.

+ References

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

+ Details

Name:	us-gaap_LossContingencyClaimsSettledAndDismissedNumber
Namespace Prefix:	us-gaap
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The total number of new claims filed pertaining to a loss contingency during the period.

+ References

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

+ Details

Name:	us-gaap_LossContingencyNewClaimsFiledNumber
Namespace Prefix:	us-gaap
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

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

+ References

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

+ Details

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