Derivative Instruments And Hedging Activities (Narrative) (Details) (USD $)	Jun. 30, 2011	Dec. 31, 2010
Credit risk derivative liabilities, at fair value	$ 90,000,000	$ 156,000,000
Net settlement amount in the event of a downgrade below investment grade	143,000,000	176,000,000
Pepco Energy Services [Member]
Cash plus borrowing capacity to meet future liquidity needs	1,400,000,000	1,200,000,000
Debt instrument unused borrowing capacity amount for subsidiary	$ 827,000,000	$ 728,000,000

Debt Instrument Unused Borrowing Capacity Amount For Subsidiary

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Namespace Prefix:	pom
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Net settlement amount in the event of a downgrade below investment grade

+ Details

Name:	pom_NetSettlementAmountInEventOfDowngradeBelowInvestmentGrade
Namespace Prefix:	pom
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value as of the balance sheet date of all credit risk derivative liabilities designated as fair value hedging instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 133
-Paragraph 17

+ Details

Name:	us-gaap_CreditRiskDerivativeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance-sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Subparagraph b
-Article 5

+ Details

Name:	us-gaap_DebtInstrumentUnusedBorrowingCapacityAmount
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant