Leasing Activities - Income Recognized from Cross-Border Energy Lease Investments (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Leases [Abstract]
Pre-tax income from PHI's cross-border energy lease investments (included in Other Revenue)	$ 2	$ 13	$ 7	$ 26
Non-cash charge to reduce carrying value of PHI's cross-border energy lease investments			(373)
Pre-tax income (loss) from PHI's cross-border energy lease investments after adjustment	2	13	(366)	26
Income tax expense (benefit) related to PHI's cross-border energy lease investments	6	3	(43)	4
Net (loss) income from PHI's cross-border energy lease investments	$ (4)	$ 10	$ (323)	$ 22

Leveraged leases income statement income from leveraged leases after adjustment.

No definition available.

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

- Definition

Non cash charge to reduce carrying value of leveraged leases.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_LeasesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Pretax lease income allocated in proportionate amounts from unearned income.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=7662751&loc=d3e45152-112736

+ Details

Name:	us-gaap_LeveragedLeasesIncomeStatementIncomeFromLeveragedLeases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The tax effect from the current year income from arrangements meeting the criteria for classification as a leveraged lease.

+ References

+ Details

Name:	us-gaap_LeveragedLeasesIncomeStatementIncomeTaxExpenseOnLeveragedLeases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The total recognized during the period for income on leases meeting the criteria for classification as leveraged leases.

+ References

+ Details

Name:	us-gaap_LeveragedLeasesIncomeStatementNetIncomeFromLeveragedLeases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration