Recently Issued Accounting Standards, Not Yet Adopted	12 Months Ended
Recently Issued Accounting Standards, Not Yet Adopted	Dec. 31, 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 expects that it will have to provide additional disclosures, but does not expect this guidance to have a significant impact on its fair value measurements. 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. In December 2011, the FASB indefinitely deferred the requirement that entities separately present items in their income statement that had been reclassified from other comprehensive income. PHI currently applies the second option in its consolidated financial statements, so PHI expects that this guidance will have minimal impact on its consolidated financial statements. 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 January 1, 2012 for PHI as it did not elect the option to apply the guidance earlier. PHI did not employ the new qualitative assessment as part of its November 1, 2011 annual impairment test. PHI does not expect the new impairment guidance to have a material impact on its consolidated financial statements. Balance Sheet (ASC 210) In December 2011, the FASB issued new disclosure requirements for assets and liabilities, such as derivatives, that are subject to contractual netting arrangements. The new disclosures will include information about the gross exposures and net exposure under contractual netting arrangements as well as how the exposures are presented in the financial statements. The new disclosures are effective beginning with PHI's March 31, 2013 consolidated financial statements. PHI is evaluating the impact of this new guidance on its consolidated financial statements.
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 expects that it will have to provide additional disclosures, but does not expect this guidance to have a significant impact on its fair value measurements.
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 expects that it will have to provide additional disclosures, but does not expect this guidance to have a significant impact on its fair value measurements. 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 January 1, 2012 for DPL as it did not elect the option to apply the guidance earlier. DPL did not employ the new qualitative assessment as part of its November 1, 2011 annual impairment test. DPL does not expect the new impairment guidance to have a material impact on its financial statements. Balance Sheet (ASC 210) In December 2011, the FASB issued new disclosure requirements for assets and liabilities, such as derivatives, that are subject to contractual netting arrangements. The new disclosures will include information about the gross exposures and net exposure under contractual netting arrangements as well as how the exposures are presented in the financial statements. The new disclosures are effective beginning with DPL's March 31, 2013 financial statements. 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 expects that it will have to provide additional disclosures, but does not expect this guidance to have a significant impact on its fair value measurements.