1.0.0.3 true Statement Of Other Comprehensive Income (USD $) In Millions false 1 $ 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 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 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 4 $ 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 1 PEPCO HOLDINGS INC 0 na true na na na No definition available. false true false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false 4 false false 0 0 false false No definition available. No authoritative reference available. false 2 Net income 2 us-gaap_NetIncomeLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 124000000 124 false false 2 true true 119000000 119 false false 3 true true 194000000 194 false false 4 true true 233000000 233 false false No definition available. No authoritative reference available. false 3 Gains (losses) on commodity derivatives designated as cash flow hedges: 2 us-gaap true 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 false false 3 false false 0 0 false false 4 false false 0 0 false false No definition available. false 4 Losses arising during period 2 us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodBeforeTax us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true -14000000 -14 false false 2 false true -675000000 -675 false false 3 false true -296000000 -296 false false 4 false true -36000000 -36 false false No definition available. No authoritative reference available. false 5 Less: amount of (losses) gains reclassified into income 2 us-gaap_OtherComprehensiveIncomeReclassificationAdjustmentOnDerivativesIncludedInNetIncomeBeforeTax us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true -97000000 -97 false false 2 false true 11000000 11 false false 3 false true -309000000 -309 false false 4 false true 93000000 93 false false No definition available. No authoritative reference available. false 6 Net gains (losses) on commodity derivatives 2 us-gaap_OtherComprehensiveIncomeDerivativesQualifyingAsHedgesBeforeTaxPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 83000000 83 false false 2 false true -686000000 -686 false false 3 false true 13000000 13 false false 4 false true -129000000 -129 false false No definition available. No authoritative reference available. true 7 Losses on Treasury Rate Locks reclassified into income 2 us-gaap_AmortizationOfDeferredHedgeGains us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 1000000 1 false false 2 false true 1000000 1 false false 3 false true 4000000 4 false false 4 false true 4000000 4 false false No definition available. No authoritative reference available. false 8 Amortization of gains and losses for prior service costs 2 us-gaap_DefinedBenefitPlanAmortizationOfNetPriorServiceCostCredit us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 0 0 false false 2 false true 0 0 false false 3 false true -10000000 -10 false false 4 false true -5000000 -5 false false No definition available. No authoritative reference available. false 9 Other comprehensive income (loss), before income taxes 2 us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 84000000 84 false false 2 false true -685000000 -685 false false 3 false true 7000000 7 false false 4 false true -130000000 -130 false false No definition available. No authoritative reference available. true 10 Income tax expense (benefit) 2 us-gaap_OtherComprehensiveIncomeLossTax us-gaap true debit duration monetary No definition available. false false false false false false false false false 1 false true 34000000 34 false false 2 false true -278000000 -278 false false 3 false true 3000000 3 false false 4 false true -52000000 -52 false false No definition available. No authoritative reference available. false 11 Other comprehensive income (loss), net of income taxes 2 us-gaap_OtherComprehensiveIncomeLossNetOfTaxPeriodIncreaseDecrease us-gaap true na duration monetary No definition available. false false false false false false false false false 1 false true 50000000 50 false false 2 false true -407000000 -407 false false 3 false true 4000000 4 false false 4 false true -78000000 -78 false false No definition available. No authoritative reference available. true 12 Comprehensive income (loss) 2 us-gaap_ComprehensiveIncomeNetOfTax us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 174000000 174 false false 2 false true -288000000 -288 false false 3 false true 198000000 198 false false 4 false true 155000000 155 false false No definition available. No authoritative reference available. true 13 POTOMAC ELECTRIC POWER CO 0 na true na na na No definition available. false true false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false 4 false false 0 0 false false No definition available. No authoritative reference available. false 14 Net income 2 us-gaap_NetIncomeLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 58000000 58 false false 2 false true 46000000 46 false false 3 false true 94000000 94 false false 4 false true 92000000 92 false false No definition available. No authoritative reference available. false 25 DELMARVA POWER & LIGHT CO /DE/ 0 na true na na na No definition available. false true false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false 4 false false 0 0 false false No definition available. No authoritative reference available. false 26 Net income 2 us-gaap_NetIncomeLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 false true 14000000 14 false false 2 false true 11000000 11 false false 3 false true 40000000 40 false false 4 false true 53000000 53 false false No definition available. No authoritative reference available. false 37 ATLANTIC CITY ELECTRIC CO 0 na true na na na No definition available. false true false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 false false 4 false false 0 0 false false No definition available. No authoritative reference available. false 38 Net income 2 us-gaap_NetIncomeLoss us-gaap true credit duration monetary No definition available. false false false false false false false false false 1 true true 23000000 23 false false 2 true true 20000000 20 false false 3 true true 33000000 33 false false 4 true true 52000000 52 false false No definition available. No authoritative reference available. false false 4 18 false Millions UnKnown UnKnown false true