XML 160 R95.htm IDEA: XBRL DOCUMENT v2.4.1.9
Stock-Based Compensation, Dividend Restrictions, and Calculations of Earnings Per Share of Common Stock - Common Stock Reserved and Unissued (Detail)
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of shares 24,136,266us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
DRP [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of shares 4,982,016us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_AwardTypeAxis
= pom_DRPMember
Pepco Holdings Long-Term Incentive Plan [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of shares 6,946,614us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_AwardTypeAxis
= pom_PepcoHoldingsLongTermIncentivePlanMember
Pepco Holdings 2012 Long-Term Incentive Plan [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of shares 7,746,773us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_AwardTypeAxis
= pom_TwoThousandTwelveLongTermIncentivePlanMember
Pepco Holdings Non-Management Directors Compensation Plan [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of shares 457,211us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_AwardTypeAxis
= pom_PepcoHoldingsNonManagementDirectorsCompensationPlanMember
Pepco Holdings Retirement Savings Plan [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Number of shares 4,003,652us-gaap_CommonStockCapitalSharesReservedForFutureIssuance
/ us-gaap_AwardTypeAxis
= pom_PepcoHoldingsRetirementSavingsPlanMember