Recently Issued Accounting Standards, Not Yet Adopted	9 Months Ended
Recently Issued Accounting Standards, Not Yet Adopted	Sep. 30, 2011
Recently Issued Accounting Standards, Not Yet Adopted	(4) RECENTLY ISSUED ACCOUNTING STANDARDS, NOT YET ADOPTED Fair Value Measurements and Disclosures (ASC 820) In May 2011, the FASB issued new guidance on fair value measurement and disclosures that will be effective beginning with PHI's March 31, 2012 consolidated financial statements. The new guidance will change how fair value is measured in specific instances and expand disclosures about fair value measurements. PHI is evaluating the impact of this new guidance on its consolidated financial statements. Comprehensive Income (ASC 220) In June 2011, the FASB issued new guidance that requires entities to report comprehensive income in one of two ways: (i) one single continuous statement that combines the income statement with the statement of other comprehensive income and totals to a comprehensive income amount; or (ii) in two separate but consecutive statements of income and other comprehensive income. PHI currently applies the second option in its financial statements, so PHI expects that this guidance will have minimal impact. The new guidance is effective beginning with PHI's March 31, 2012 consolidated financial statements. Goodwill (ASC 350) In September 2011, the FASB issued new guidance that changes the annual and interim assessments of goodwill for impairment. The new guidance modifies the required annual impairment test by giving entities the option to perform a qualitative assessment of whether it is more likely than not that goodwill is impaired before performing a quantitative assessment. The new guidance also amends the events and circumstances that entities should assess to determine whether an interim quantitative impairment test is necessary. The new guidance is effective beginning with PHI's March 31, 2012 consolidated financial statements and PHI is evaluating the impact. The new guidance can be adopted prior to March 31, 2012 but PHI does not plan to employ the new qualitative assessment as part of its November 1, 2011 annual impairment test.
Potomac Electric Power Co [Member]
Recently Issued Accounting Standards, Not Yet Adopted	(4) RECENTLY ISSUED ACCOUNTING STANDARDS, NOT YET ADOPTED Fair Value Measurements and Disclosures (ASC 820) In May 2011, the FASB issued new guidance on fair value measurement and disclosures that will be effective beginning with Pepco's March 31, 2012 financial statements. The new guidance will change how fair value is measured in specific instances and expand disclosures about fair value measurements. Pepco is evaluating the impact of this new guidance on its financial statements. Compensation Retirement Benefits Multiemployer Plans (ASC 715-80) In September 2011, the FASB issued new disclosure requirements for participants in multiemployer pension and postretirement benefit plans. The disclosures are intended to indicate the financial health of the plans and the potential future cash flow implications for participants in the plans. The new disclosures are effective beginning with Pepco's December 31, 2011 financial statements and prior periods presented. Pepco is evaluating the impact of this new guidance on its financial statements.
Delmarva Power & Light Co/De [Member]
Recently Issued Accounting Standards, Not Yet Adopted	(4) RECENTLY ISSUED ACCOUNTING STANDARDS, NOT YET ADOPTED Fair Value Measurements and Disclosures (ASC 820) In May 2011, the FASB issued new guidance on fair value measurement and disclosures that will be effective beginning with DPL's March 31, 2012 financial statements. The new guidance will change how fair value is measured in specific instances and expand disclosures about fair value measurements. DPL is evaluating the impact of this new guidance on its financial statements. Goodwill (ASC 350) In September 2011, the FASB issued new guidance that changes the annual and interim assessments of goodwill for impairment. The new guidance modifies the required annual impairment test by giving entities the option to perform a qualitative assessment of whether it is more likely than not that goodwill is impaired before performing a quantitative assessment. The new guidance also amends the events and circumstances that entities should assess to determine whether an interim quantitative impairment test is necessary. The new guidance is effective beginning with DPL's March 31, 2012 financial statements and DPL is evaluating the impact. The new guidance can be adopted prior to March 31, 2012, but DPL does not plan to employ the new qualitative assessment as part of its November 1, 2011 annual impairment test. Compensation Retirement Benefits Multiemployer Plans (ASC 715-80) In September 2011, the FASB issued new disclosure requirements for participants in multiemployer pension and postretirement benefit plans. The disclosures are intended to indicate the financial health of the plans and the potential future cash flow implications for participants in the plans. The new disclosures are effective beginning with DPL's December 31, 2011 financial statements and prior periods presented. DPL is evaluating the impact of this new guidance on its financial statements.
Atlantic City Electric Co [Member]
Recently Issued Accounting Standards, Not Yet Adopted	(4) RECENTLY ISSUED ACCOUNTING STANDARDS, NOT YET ADOPTED Fair Value Measurements and Disclosures (ASC 820) In May 2011, the FASB issued new guidance on fair value measurement and disclosures that will be effective beginning with ACE's March 31, 2012 consolidated financial statements. The new guidance will change how fair value is measured in specific instances and expand disclosures about fair value measurements. ACE is evaluating the impact of this new guidance on its consolidated financial statements. Compensation Retirement Benefits Multiemployer Plans (ASC 715-80) In September 2011, the FASB issued new disclosure requirements for participants in multiemployer pension and postretirement benefit plans. The disclosures are intended to indicate the financial health of the plans and the potential future cash flow implications for participants in the plans. The new disclosures are effective beginning with ACE's December 31, 2011 consolidated financial statements and prior periods presented. ACE is evaluating the impact of this new guidance on its consolidated financial statements.