Borrowing capacity under the credit facilities

No definition available.

Name:	pom_BorrowingCapacityUnderCreditFacilities
Namespace Prefix:	pom_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash collateral paid out per agreement and will be returned at end of agreement

+ References

No definition available.

+ Details

Name:	pom_CashCollateralPaidOutPerAgreementAndWillBeReturnedAtEndOfAgreement
Namespace Prefix:	pom_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Combined Maximum Amount Of Credit Facility Available To Parent

+ References

No definition available.

+ Details

Name:	pom_CombinedMaximumAmountOfCreditFacilityAvailableToParent
Namespace Prefix:	pom_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Commercial Paper Weighted Average Interest Rate

+ References

No definition available.

+ Details

Name:	pom_CommercialPaperWeightedAverageInterestRate
Namespace Prefix:	pom_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Commercial Paper Weighted Average Maturity

+ References

No definition available.

+ Details

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Namespace Prefix:	pom_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument Maturity Period

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument Maturity Year

+ References

No definition available.

+ Details

Name:	pom_DebtInstrumentMaturityYear
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- Definition

Debt Instrument Variable Interest Rate In Addition To Federal Funds Effective Rate

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument Variable Interest Rate In Addition To One Month LIBORs Effective Rate

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line Of Credit Facility Extended Expiration Date

+ References

No definition available.

+ Details

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Data Type:	us-types:dateStringItemType
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Period Type:	duration

- Definition

Long Term Commercial Paper Program Maximum

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

Parent Company Credit Facility Letter Of Credit Maximum

+ References

No definition available.

+ Details

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Namespace Prefix:	pom_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Ratio Of Deferrable Interest Subordinated Debt To Total Capitalization

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Ratio Of Indebtedness To Total Capitalization

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Same Day Borrowings Maximum Percentage Amount

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Subsidiary borrowing limit under parents credit facility

+ References

No definition available.

+ Details

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Namespace Prefix:	pom_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Utility Subsidiaries Combined Cash And Borrowings Capacity

+ References

No definition available.

+ Details

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

- Definition

The percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
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- Definition

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number APB14-1

-Paragraph 31

-Subparagraph b

-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.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13476-108611

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Period Type:	instant

- Definition

Interest rate stated in the contractual debt agreement.

+ References

+ Details

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- Details

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22(a)(2))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-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.

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- Definition

Amount of the required periodic payments applied to principal.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 20, 22

-Article 5

+ Details

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Period Type:	instant

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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- Definition

Date the credit facility terminates, in CCYY-MM-DD format.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-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.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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- Definition

Carrying value as of the balance sheet date of the current portion of long-term unsecured obligations issued by corporations and other borrowers to investors (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19,20)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19

-Article 5

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Debt (Detail) (USD $)	6 Months Ended		1 Months Ended						6 Months Ended			1 Months Ended		6 Months Ended	1 Months Ended		1 Months Ended			1 Months Ended			6 Months Ended	1 Months Ended		1 Months Ended				6 Months Ended
Debt (Detail) (USD $)	Jun. 30, 2012	Dec. 31, 2011	Apr. 04, 2012 First Mortgage Bonds [Member]	Apr. 24, 2012 Term Loan Agreement [Member]	Jun. 30, 2012 Term Loan Agreement [Member]	Apr. 24, 2012 In Addition To Federal Funds Rate [Member]	Apr. 24, 2012 Eurodollar Rate [Member]	Apr. 30, 2012 Industrial Development Authority Of The City Of Alexandria Virginia [Member] Pollution Control Revenue Refunding Bonds [Member]	Jun. 30, 2012 Maximum [Member]	Jun. 30, 2012 Maximum [Member] Term Loan Agreement [Member]	Jun. 30, 2012 Potomac Electric Power Co [Member] Day	Apr. 04, 2012 Potomac Electric Power Co [Member] First Mortgage Bonds [Member]	Apr. 30, 2012 Potomac Electric Power Co [Member] Industrial Development Authority Of The City Of Alexandria Virginia [Member] Pollution Control Revenue Refunding Bonds [Member]	Jun. 30, 2012 Delmarva Power & Light Co/De [Member] Day	Jun. 26, 2012 Delmarva Power & Light Co/De [Member] First Mortgage Bonds [Member]	Jun. 26, 2012 Delmarva Power & Light Co/De [Member] Pollution Control Revenue Refunding Bonds [Member]	Jun. 28, 2012 Delmarva Power & Light Co/De [Member] Pollution Control Revenue Refunding Bonds [Member] Subsequent Event [Member]	Jun. 26, 2012 Delmarva Power & Light Co/De [Member] Delaware Economic Development Authority [Member]	Jun. 26, 2012 Delmarva Power & Light Co/De [Member] Commercial Paper [Member]	Jun. 01, 2012 Delmarva Power & Light Co/De [Member] 0.75% Pollution Control Refunding Revenue Bonds Due On 2026 [Member]	Jun. 01, 2012 Delmarva Power & Light Co/De [Member] 1.80% Pollution Control Refunding Revenue Bonds Due On 2025 [Member]	Jun. 01, 2012 Delmarva Power & Light Co/De [Member] 2.30% Pollution Control Refunding Revenue Bonds Due On 2028 [Member]	Jun. 30, 2012 Atlantic City Electric Co [Member] Day	Apr. 30, 2012 Atlantic City Electric Co [Member] Series 2002-1 Bonds Class A-3 [Member]	Jul. 31, 2012 Atlantic City Electric Co [Member] Series 2002-1 Bonds Class A-3 [Member] Subsequent Event [Member]	Apr. 30, 2012 Atlantic City Electric Co [Member] Series 2003-1 Bonds Class A-2 [Member]	Jul. 31, 2012 Atlantic City Electric Co [Member] Series 2003-1 Bonds Class A-2 [Member] Subsequent Event [Member]	Jun. 30, 2012 Pepco Energy Services [Member]	Dec. 31, 2011 Pepco Energy Services [Member]	Jun. 30, 2012 Pepco Holdings Inc [Member] Day
Debt Instrument [Line Items]
Line of credit facility expiration date	Aug. 01, 2016										Aug. 01, 2016			Aug. 01, 2016									Aug. 01, 2016
Line of credit facility extended expiration date	2017-08-01										2017-08-01			2017-08-01									2017-08-01
Line of credit facility maximum borrowing capacity	$ 1,500,000,000
Parent company credit facility letter of credit, maximum	500,000,000
Same day borrowings maximum percentage amount	10.00%
Credit facility borrowing capacity	750,000,000										250,000,000			250,000,000									250,000,000					383,000,000	283,000,000
Maximum amount of credit available to parent	1,250,000,000
Subsidiary borrowing limit under parent's credit facility											500,000,000			500,000,000									500,000,000
Debt instrument variable interest rate, interest rate before LIBOR	0.50%
Debt instrument variable interest rate in addition to one month LIBOR's effective rate	1.00%
Ratio of indebtedness to total capitalization									65.00%	65.00%
Ratio of deferrable interest subordinated debt to total capitalization									15.00%	15.00%
Borrowing capacity under the credit facility	969,000,000	994,000,000
Utility subsidiaries combined cash and borrowing capacity	586,000,000	711,000,000
On-going commercial paper	875,000,000										500,000,000			500,000,000									250,000,000
Commercial paper outstanding	365,000,000										108,000,000			0									74,000,000
Commercial paper weighted average interest rate	0.81%										0.41%			0.41%									0.41%
Commercial paper weighted average maturity in days											4			5									2							13
Debt instrument principal payment																								6,000,000		2,000,000
Debt instrument, carrying value			200,000,000	200,000,000								200,000,000			250,000,000		31,000,000			34,500,000	15,000,000	16,200,000			6,000,000		2,000,000
Debt instrument, interest percentage			3.05%		1.125%			5.375%				3.05%	5.375%		4.00%		5.20%			0.75%	1.80%	2.30%
Debt instrument, maturity date			Apr. 01, 2022	Apr. 23, 2013								Apr. 01, 2022			Jun. 01, 2042
Debt instrument, amount outstanding								38,300,000					38,300,000			65,700,000		31,000,000	215,000,000
Debt instrument, maturity year								2024					2024
Debt instrument, maturity year																	2019			2026	2025	2028
Margin added to stated rate				0.875%		0.50%	1.00%
Cash collateral posted																												61,000,000	112,000,000
Letters of credit posted																												$ 1,000,000	$ 1,000,000