Significant Accounting Policies	3 Months Ended
Significant Accounting Policies	Mar. 31, 2012
Significant Accounting Policies	(2) SIGNIFICANT ACCOUNTING POLICIES Financial Statement Presentation Pepco Holdings' unaudited consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (GAAP). Pursuant to the rules and regulations of the Securities and Exchange Commission, certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with GAAP have been omitted. Therefore, these consolidated financial statements should be read along with the annual consolidated financial statements included in PHI's annual report on Form 10-K for the year ended December 31, 2011, as amended to include the executive compensation and other information required by Part III of Form 10-K (which information originally had been omitted as permitted by that form). In the opinion of PHI's management, the consolidated financial statements contain all adjustments (which all are of a normal recurring nature) necessary to state fairly Pepco Holdings' financial condition as of March 31, 2012, in accordance with GAAP. The year-end December 31, 2011 consolidated balance sheet was derived from audited consolidated financial statements, but does not include all disclosures required by GAAP. Interim results for the three months ended March 31, 2012 may not be indicative of PHI's results that will be realized for the full year ending December 31, 2012. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent assets and liabilities in the consolidated financial statements and accompanying notes. Although Pepco Holdings believes that its estimates and assumptions are reasonable, they are based upon information available to management at the time the estimates are made. Actual results may differ significantly from these estimates. Significant matters that involve the use of estimates include the assessment of goodwill and long-lived assets for impairment, fair value calculations for derivative instruments, the costs of providing pension and other postretirement benefits, evaluation of the probability of recovery of regulatory assets, accrual of storm restoration costs, accrual of self-insurance reserves for general and auto liability claims, accrual of interest related to income taxes, accrual of unbilled revenue, recognition of changes in network service transmission rates for prior service year costs, and the recognition of income tax benefits for investments in finance leases held in trust associated with PHI's portfolio of cross-border energy lease investments. Additionally, PHI is subject to legal, regulatory and other proceedings and claims that arise in the ordinary course of its business. PHI records an estimated liability for these proceedings and claims, when it is probable that a loss has been incurred and the loss is reasonably estimable. Consolidation of Variable Interest Entities PHI assesses its contractual arrangements with variable interest entities to determine whether it is the primary beneficiary and thereby has to consolidate the entities in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 810. The guidance addresses conditions under which an entity should be consolidated based upon variable interests rather than voting interests. Subsidiaries of PHI have the following contractual arrangements to which the guidance applies. ACE Power Purchase Agreements PHI, through its ACE subsidiary, is a party to three power purchase agreements (PPAs) with unaffiliated, non-utility generators (NUGs) totaling 459 megawatts. One of the agreements ends in 2016 and the other two end in 2024. PHI was unable to obtain sufficient information to determine whether these three entities were variable interest entities or if ACE was the primary beneficiary. As a result, PHI applied the scope exemption from the consolidation guidance for enterprises that have not been able to obtain such information. Net purchase activities with the NUGs for the three months ended March 31, 2012 and 2011 were approximately $51 million and $57 million, respectively, of which approximately $50 million and $53 million, respectively, consisted of power purchases under the PPAs. The power purchase costs are recoverable from ACE's customers through regulated rates. DPL Renewable Energy Transactions DPL is subject to Renewable Energy Portfolio Standards (RPS) in the state of Delaware that require it to obtain renewable energy credits (RECs) for energy delivered to its customers. DPL's costs associated with obtaining RECs to fulfill its RPS obligations are recoverable from its customers by law. PHI, through its DPL subsidiary, has entered into three land-based wind PPAs in the aggregate amount of 128 megawatts and one solar PPA with a 10 megawatt facility as of March 31, 2012. All of the facilities associated with these PPAs are operational, and DPL is obligated to purchase energy and RECs in amounts generated and delivered by the wind facilities and solar renewable energy credits (SRECs) from the solar facility at rates that are primarily fixed under these agreements. PHI has concluded that consolidation is not required for any of these agreements under the FASB guidance on the consolidation of variable interest entities. DPL is obligated to purchase energy and RECs from one of the wind facilities through 2024 in amounts not to exceed 50 megawatts, the second of the wind facilities through 2031 in amounts not to exceed 40 megawatts, and the third facility through 2031 in amounts not to exceed 38 megawatts. DPL's purchases under the three wind PPAs totaled $9 million and $5 million for the three months ended March 31, 2012 and 2011, respectively. The term of the agreement with the solar facility is 20 years and DPL is obligated to purchase SRECs in an amount up to 70 percent of the energy output at a fixed price. DPL's purchases under the solar agreement were zero for the three months ended March 31, 2012. On October 18, 2011, the Delaware Public Service Commission (DPSC) approved a tariff submitted by DPL in accordance with the requirements of the RPS specific to fuel cell facilities totaling 30 megawatts to be constructed by a qualified fuel cell provider. The tariff and the RPS establish that DPL would be an agent to collect payments in advance from its distribution customers and remit them to the qualified fuel cell provider for each megawatt hour of energy produced by the fuel cell facilities over 21 years. DPL would have no liability to the qualified fuel cell provider other than to remit payments collected from its distribution customers pursuant to the tariff. The RPS provides for a reduction in DPL's REC requirements based upon the actual energy output of the facilities. In June 2012, a 3 megawatt generation facility is expected to be placed into service under the tariff. A 27 megawatt generation facility is expected to be placed into service in 5 megawatt increments beginning in January 2013. PHI has concluded that DPL would account for this arrangement as an agency transaction. Atlantic City Electric Transition Funding LLC Atlantic City Electric Transition Funding LLC (ACE Funding) was established in 2001 by ACE solely for the purpose of securitizing authorized portions of ACE's recoverable stranded costs through the issuance and sale of bonds (Transition Bonds). The proceeds of the sale of each series of Transition Bonds have been transferred to ACE in exchange for the transfer by ACE to ACE Funding of the right to collect non-bypassable transition bond charges (the Transition Bond Charges) from ACE customers pursuant to bondable stranded costs rate orders issued by the New Jersey Board of Public Utilities (NJBPU) in an amount sufficient to fund the principal and interest payments on the Transition Bonds and related taxes, expenses and fees (Bondable Transition Property). ACE collects the Transition Bond Charges from its customers on behalf of ACE Funding and the holders of the Transition Bonds. The assets of ACE Funding, including the Bondable Transition Property, and the Transition Bond Charges collected from ACE's customers, are not available to creditors of ACE. The holders of the Transition Bonds have recourse only to the assets of ACE Funding. ACE owns 100 percent of the equity of ACE Funding and PHI consolidates ACE Funding in its financial statements as ACE is the primary beneficiary of ACE Funding under the variable interest entity consolidation guidance. ACE Standard Offer Capacity Agreements In April 2011, ACE entered into three Standard Offer Capacity Agreements (SOCAs) by order of the NJBPU, each with a different generation company. The SOCAs were established under a New Jersey law enacted to promote the construction of qualified electric generation facilities in New Jersey. The SOCAs are 15-year, financially settled transactions approved by the NJBPU that allow generators to receive payments from, or make payments to, ACE based on the difference between the fixed price in the SOCAs and the price for capacity that clears PJM Interconnection, LLC (PJM). Each of the other electricity distribution companies (EDCs) in New Jersey has entered into SOCAs having the same terms with the same generation companies. The annual share of payments or receipts for ACE and the other EDCs is based upon each company's annual proportion of the total New Jersey load attributable to all EDCs. The NJBPU has approved full recovery from distribution customers of payments made by ACE and the other EDCs, and distribution customers would be entitled to any payments received by ACE and the other EDCs. Currently, PHI believes that FASB guidance on derivative accounting and the accounting for regulated operations would apply to ACE's obligations under the SOCA once the related capacity has cleared a PJM auction. Once cleared, the gain (loss) associated with the fair value of a derivative would be offset by the recognition of a regulatory liability (asset). The next PJM capacity auction is scheduled for May 2012. PHI has concluded that consolidation is not required for the SOCAs under the FASB guidance on the consolidation of variable interest entities. Goodwill Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired at the acquisition date. Substantially all of Pepco Holdings' goodwill was generated by Pepco's acquisition of Conectiv (now Conectiv, LLC (Conectiv)) in 2002 and is allocated entirely to Power Delivery for purposes of impairment testing based on the aggregation of its components because its utilities have similar characteristics. Pepco Holdings tests its goodwill for impairment annually as of November 1 and whenever an event occurs or circumstances change in the interim that would more likely than not reduce the fair value of a reporting unit below the carrying amount of its net assets. Factors that may result in an interim impairment test include, but are not limited to: a change in the identified reporting units; an adverse change in business conditions; a protracted decline in PHI's stock price causing market capitalization to fall below book value; an adverse regulatory action; or an impairment of long-lived assets in the reporting unit. PHI concluded that an interim impairment test was not required during the three months ended March 31, 2012. Taxes Assessed by a Governmental Authority on Revenue-Producing Transactions Taxes included in Pepco Holdings' gross revenues were $92 million and $96 million for the three months ended March 31, 2012 and 2011, respectively. Reclassifications and Adjustments Certain prior period amounts have been reclassified in order to conform to the current period presentation. The following adjustments have been recorded and are not considered material either individually or in the aggregate: Pepco Energy Services Derivative Accounting Adjustments During the first quarter of 2011, PHI recorded an adjustment associated with an increase in the value of certain derivatives from October 1, 2010 to December 31, 2010, which had been erroneously recorded in other comprehensive income at December 31, 2010. This adjustment resulted in an increase in revenue and pre-tax earnings of $2 million for the three months ended March 31, 2011. Income Tax Adjustments During the first quarter of 2011, Pepco recorded an adjustment to correct certain income tax errors related to prior periods associated with interest on uncertain tax positions. The adjustment resulted in an increase in income tax expense of $1 million for the three months ended March 31, 2011.
Potomac Electric Power Co [Member]
Significant Accounting Policies	(2) SIGNIFICANT ACCOUNTING POLICIES Financial Statement Presentation Pepco's unaudited financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (GAAP). Pursuant to the rules and regulations of the Securities and Exchange Commission, certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been omitted. Therefore, these financial statements should be read along with the annual financial statements included in Pepco's annual report on Form 10-K for the year ended December 31, 2011, as amended to include the executive compensation and other information required by Part III of Form 10-K (which information originally had been omitted as permitted by that form). In the opinion of Pepco's management, the financial statements contain all adjustments (which all are of a normal recurring nature) necessary to state fairly Pepco's financial condition as of March 31, 2012, in accordance with GAAP. The year-end December 31, 2011 balance sheet was derived from audited financial statements, but does not include all disclosures required by GAAP. Interim results for the three months ended March 31, 2012 may not be indicative of results that will be realized for the full year ending December 31, 2012. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent assets and liabilities in the financial statements and accompanying notes. Although Pepco believes that its estimates and assumptions are reasonable, they are based upon information available to management at the time the estimates are made. Actual results may differ significantly from these estimates. Significant matters that involve the use of estimates include the assessment of contingencies, the calculation of future cash flows and fair value amounts for use in asset impairment evaluations, pension and other postretirement benefits assumptions, the assessment of the probability of recovery of regulatory assets, accrual of storm restoration costs, accrual of unbilled revenue, recognition of changes in network service transmission rates for prior service year costs, accrual of self-insurance reserves for general and auto liability claims, and income tax provisions and reserves. Additionally, Pepco is subject to legal, regulatory and other proceedings and claims that arise in the ordinary course of its business. Pepco records an estimated liability for these proceedings and claims when it is probable that a loss has been incurred and the loss is reasonably estimable. Taxes Assessed by a Governmental Authority on Revenue-Producing Transactions Taxes included in Pepco's gross revenues were $84 million and $85 million for the three months ended March 31, 2012 and 2011, respectively. Reclassifications and Adjustments Certain prior period amounts have been reclassified in order to conform to the current period presentation. The following adjustment has been recorded and is not considered material: Income Tax Adjustments During the first quarter of 2011, Pepco recorded an adjustment to correct certain income tax errors related to prior periods associated with interest on uncertain tax positions. The adjustment resulted in an increase in income tax expense of $1 million for the three months ended March 31, 2011.
Delmarva Power & Light Co/De [Member]
Significant Accounting Policies	(2) SIGNIFICANT ACCOUNTING POLICIES Financial Statement Presentation DPL's unaudited financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (GAAP). Pursuant to the rules and regulations of the Securities and Exchange Commission, certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been omitted. Therefore, these financial statements should be read along with the annual financial statements included in DPL's annual report on Form 10-K for the year ended December 31, 2011, as amended to include the executive compensation and other information required by Part III of Form 10-K (which information originally had been omitted as permitted by that form). In the opinion of DPL's management, the financial statements contain all adjustments (which all are of a normal recurring nature) necessary to state fairly DPL's financial condition as of March 31, 2012, in accordance with GAAP. The year-end December 31, 2011 balance sheet was derived from audited financial statements, but does not include all disclosures required by GAAP. Interim results for the three months ended March 31, 2012 may not be indicative of DPL's results that will be realized for the full year ending December 31, 2012. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent assets and liabilities in the financial statements and accompanying notes. Although DPL believes that its estimates and assumptions are reasonable, they are based upon information available to management at the time the estimates are made. Actual results may differ significantly from these estimates. Significant matters that involve the use of estimates include the assessment of contingencies, the calculation of future cash flows and fair value amounts for use in asset and goodwill impairment evaluations, fair value calculations for derivative instruments, pension and other postretirement benefits assumptions, the assessment of the probability of recovery of regulatory assets, accrual of storm restoration costs, accrual of unbilled revenue, recognition of changes in network service transmission rates for prior service year costs, accrual of self-insurance reserves for general and auto liability claims, and income tax provisions and reserves. Additionally, DPL is subject to legal, regulatory and other proceedings and claims that arise in the ordinary course of its business. DPL records an estimated liability for these proceedings and claims when it is probable that a loss has been incurred and the loss is reasonably estimable. Consolidation of Variable Interest Entities - DPL Renewable Energy Transactions DPL assesses its contractual arrangements with variable interest entities to determine whether it is the primary beneficiary and thereby has to consolidate the entities in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 810. The guidance addresses conditions under which an entity should be consolidated based upon variable interests rather than voting interests. DPL is subject to Renewable Energy Portfolio Standards (RPS) in the state of Delaware that require it to obtain renewable energy credits (RECs) for energy delivered to its customers. DPL's costs associated with obtaining RECs to fulfill its RPS obligations are recoverable from its customers by law. DPL has entered into three land-based wind power purchase agreements (PPAs) in the aggregate amount of 128 megawatts and one solar PPA with a 10 megawatt facility as of March 31, 2012. All of the facilities associated with these PPAs are operational, and DPL is obligated to purchase energy and RECs in amounts generated and delivered by the wind facilities and solar renewable energy credits (SRECs) from the solar facility at rates that are primarily fixed under these agreements. DPL has concluded that consolidation is not required for any of these agreements under the FASB guidance on the consolidation of variable interest entities. DPL is obligated to purchase energy and RECs from one of the wind facilities through 2024 in amounts not to exceed 50 megawatts, the second of the wind facilities through 2031 in amounts not to exceed 40 megawatts, and the third facility through 2031 in amounts not to exceed 38 megawatts. DPL's purchases under the three wind PPAs totaled $9 million and $5 million for the three months ended March 31, 2012 and 2011, respectively. The term of the agreement with the solar facility is 20 years and DPL is obligated to purchase SRECs in an amount up to 70 percent of the energy output at a fixed price. DPL's purchases under the solar agreement were zero for the three months ended March 31, 2012. On October 18, 2011, the Delaware Public Service Commission (DPSC) approved a tariff submitted by DPL in accordance with the requirements of the RPS specific to fuel cell facilities totaling 30 megawatts to be constructed by a qualified fuel cell provider. The tariff and the RPS establish that DPL would be an agent to collect payments in advance from its distribution customers and remit them to the qualified fuel cell provider for each megawatt hour of energy produced by the fuel cell facilities over 21 years. DPL would have no liability to the qualified fuel cell provider other than to remit payments collected from its distribution customers pursuant to the tariff. The RPS provide for a reduction in DPL's REC requirements based upon the actual energy output of the facilities. In June 2012, a 3 megawatt generation facility is expected to be placed into service under the tariff. A 27 megawatt generation facility is expected to be placed into service in 5 megawatt increments beginning in January 2013. PHI has concluded that DPL would account for this arrangement as an agency transaction. Goodwill Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired at the acquisition date. All of DPL's goodwill was generated by DPL's acquisition of Conowingo Power Company in 1995. DPL tests its goodwill for impairment annually and whenever an event occurs or circumstances change in the interim that would more likely than not reduce the fair value of DPL below the carrying amount of its net assets. DPL performs its annual impairment test as of November 1. Factors that may result in an interim impairment test include, but are not limited to: a change in the identified reporting units; an adverse change in business conditions; an adverse regulatory action; or an impairment of DPL's long-lived assets. DPL concluded that an interim impairment test was not required during the three months ended March 31, 2012. Taxes Assessed by a Governmental Authority on Revenue-Producing Transactions Taxes included in DPL's gross revenues were $4 million and $5 million for the three months ended March 31, 2012 and 2011, respectively.
Atlantic City Electric Co [Member]
Significant Accounting Policies	(2) SIGNIFICANT ACCOUNTING POLICIES Financial Statement Presentation ACE's unaudited consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (GAAP). Pursuant to the rules and regulations of the Securities and Exchange Commission, certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with GAAP have been omitted. Therefore, these consolidated financial statements should be read along with the annual consolidated financial statements included in ACE's annual report on Form 10-K for the year ended December 31, 2011, as amended to include the executive compensation and other information required by Part III of Form 10-K (which information originally had been omitted as permitted by that form). In the opinion of ACE's management, the consolidated financial statements contain all adjustments (which all are of a normal recurring nature) necessary to state fairly ACE's financial condition as of March 31, 2012, in accordance with GAAP. The year-end December 31, 2011 consolidated balance sheet was derived from audited consolidated financial statements, but does not include all disclosures required by GAAP. Interim results for the three months ended March 31, 2012 may not be indicative of ACE's results that will be realized for the full year ending December 31, 2012. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures of contingent assets and liabilities in the consolidated financial statements and accompanying notes. Although ACE believes that its estimates and assumptions are reasonable, they are based upon information available to management at the time the estimates are made. Actual results may differ significantly from these estimates. Significant matters that involve the use of estimates include the assessment of contingencies, the calculation of future cash flows and fair value amounts for use in asset impairment evaluations, pension and other postretirement benefits assumptions, the assessment of the probability of recovery of regulatory assets, accrual of storm restoration costs, accrual of unbilled revenue, recognition of changes in network service transmission rates for prior service year costs, accrual of self-insurance reserves for general and auto liability claims, and income tax provisions and reserves. Additionally, ACE is subject to legal, regulatory and other proceedings and claims that arise in the ordinary course of its business. ACE records an estimated liability for these proceedings and claims when it is probable that a loss has been incurred and the loss is reasonably estimable. Consolidation of Variable Interest Entities ACE assesses its contractual arrangements with variable interest entities to determine whether it is the primary beneficiary and thereby has to consolidate the entities in accordance with Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) 810. The guidance addresses conditions under which an entity should be consolidated based upon variable interests rather than voting interests. ACE Power Purchase Agreements ACE is a party to three power purchase agreements (PPAs) with unaffiliated, non-utility generators (NUGs) totaling 459 megawatts. One of the agreements ends in 2016 and the other two end in 2024. ACE was unable to obtain sufficient information to determine whether these three entities were variable interest entities or if ACE was the primary beneficiary. As a result, ACE applied the scope exemption from the consolidation guidance for enterprises that have not been able to obtain such information. Net purchase activities with the NUGs for the three months ended March 31, 2012 and 2011 were approximately $51 million and $57 million, respectively, of which approximately $50 million and $53 million, respectively, consisted of power purchases under the PPAs. The power purchase costs are recoverable from ACE's customers through regulated rates. Atlantic City Electric Transition Funding LLC Atlantic City Electric Transition Funding LLC (ACE Funding) was established in 2001 by ACE solely for the purpose of securitizing authorized portions of ACE's recoverable stranded costs through the issuance and sale of bonds (Transition Bonds). The proceeds of the sale of each series of Transition Bonds have been transferred to ACE in exchange for the transfer by ACE to ACE Funding of the right to collect non-bypassable transition bond charges (the Transition Bond Charges) from ACE customers pursuant to bondable stranded costs rate orders issued by the New Jersey Board of Public Utilities (NJBPU) in an amount sufficient to fund the principal and interest payments on the Transition Bonds and related taxes, expenses and fees (Bondable Transition Property). ACE collects the Transition Bond Charges from its customers on behalf of ACE Funding and the holders of the Transition Bonds. The assets of ACE Funding, including the Bondable Transition Property, and the Transition Bond Charges collected from ACE's customers, are not available to creditors of ACE. The holders of the Transition Bonds have recourse only to the assets of ACE Funding. ACE owns 100 percent of the equity of ACE Funding and consolidates ACE Funding in its financial statements as ACE is the primary beneficiary of ACE Funding under the variable interest entity consolidation guidance. ACE Standard Offer Capacity Agreements In April 2011, ACE entered into three Standard Offer Capacity Agreements (SOCAs) by order of the NJBPU, each with a different generation company. The SOCAs were established under a New Jersey law enacted to promote the construction of qualified electric generation facilities in New Jersey. The SOCAs are 15-year, financially settled transactions approved by the NJBPU that allow generators to receive payments from, or make payments to, ACE based on the difference between the fixed price in the SOCAs and the price for capacity that clears PJM Interconnection, LLC (PJM). Each of the other electricity distribution companies (EDCs) in New Jersey has entered into SOCAs having the same terms with the same generation companies. The annual share of payments or receipts for ACE and the other EDCs is based upon each company's annual proportion of the total New Jersey load attributable to all EDCs. The NJBPU has approved full recovery from distribution customers of payments made by ACE and the other EDCs, and distribution customers would be entitled to any payments received by ACE and the other EDCs. Currently, ACE believes that FASB guidance on derivative accounting and the accounting for regulated operations would apply to a SOCA once capacity has cleared a PJM auction. Once cleared, the gain (loss) associated with the fair value of a derivative would be offset by the recognition of a regulatory liability (asset). The next PJM capacity auction is scheduled for May 2012. ACE has concluded that consolidation is not required for the SOCAs under the FASB guidance on the consolidation of variable interest entities. Taxes Assessed by a Governmental Authority on Revenue-Producing Transactions Taxes included in ACE's gross revenues were $4 million and $6 million for the three months ended March 31, 2012 and 2011, respectively.

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The entire disclosure for all significant accounting policies of the reporting entity.

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