1.0.0.3 true Entity Information (USD $) false 1 $ false false false 2 $ true false false false PEPCO HOLDINGS INC dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_ParentCompanyMember dei_LegalEntityAxis explicitMember Shares Standard http://www.xbrl.org/2003/instance shares 0 USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 USDperShareItemType Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares 0 false 3 $ true false false false PEPCO HOLDINGS INC dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi us-gaap_ParentCompanyMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 false 4 $ true false false false POTOMAC ELECTRIC POWER CO dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi pom_PotomacElectricPowerCoMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 false 5 $ true false false false DELMARVA POWER & LIGHT CO /DE/ dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi pom_DelmarvaPowerLightCoMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 false 6 $ true false false false ATLANTIC CITY ELECTRIC CO dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi pom_AtlanticCityElectricCoMember dei_LegalEntityAxis explicitMember USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 2 Entity [Text Block] 0 dei_EntityTextBlock dei false na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 true false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false No definition available. false 3 Trading Symbol 1 dei_TradingSymbol dei false na duration normalizedstring No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 POM POM true false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false No definition available. 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No authoritative reference available. false 9 Entity Voluntary Filers 1 dei_EntityVoluntaryFilers dei false na duration na No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 No No true false 3 false false 0 0 true false 4 false false 0 0 No No true false 5 false false 0 0 No No true false 6 false false 0 0 No No true false No definition available. No authoritative reference available. false 10 Entity Filer Category 1 dei_EntityFilerCategory dei false na duration na No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 Large Accelerated Filer Large Accelerated Filer true false 3 false false 0 0 true false 4 false false 0 0 Non-accelerated Filer Non-accelerated Filer true false 5 false false 0 0 Non-accelerated Filer Non-accelerated Filer true false 6 false false 0 0 Non-accelerated Filer Non-accelerated Filer true false No definition available. No authoritative reference available. false 11 Entity Common Stock, Shares Outstanding 1 dei_EntityCommonStockSharesOutstanding dei false na instant shares No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false true 220820630 220820630 true false 3 false false 0 0 true false 4 false true 100 100 true false 5 false true 1000 1000 true false 6 false true 8546017 8546017 true false No definition available. No authoritative reference available. false 12 Entity Public Float 1 dei_EntityPublicFloat dei false credit instant monetary No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 true false 3 true true 5200000000 5200000000 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false No definition available. No authoritative reference available. false false 6 11 false NoRounding NoRounding UnKnown false true