Newly Adopted Accounting Standards	6 Months Ended
Newly Adopted Accounting Standards	Jun. 30, 2011
Newly Adopted Accounting Standards	(3) NEWLY ADOPTED ACCOUNTING STANDARDS Fair Value Measurements and Disclosures (ASC 820) The FASB issued new disclosure requirements that require significant items within the reconciliation of the Level 3 valuation category to be presented in separate categories for purchases, sales, issuances and settlements. The guidance was effective beginning with PHI's March 31, 2011 financial statements. PHI has included the new disclosure requirements in Note (14), "Fair Value Disclosures," to its financial statements. Goodwill (ASC 350) The FASB issued new guidance on performing goodwill impairment tests that was effective beginning January 1, 2011 for PHI. Under the new guidance, the carrying value of the reporting unit must include the liabilities that are part of the capital structure of the reporting unit. PHI already allocates liabilities to the reporting unit when performing its goodwill impairment test, so the new guidance did not change PHI's goodwill impairment test methodology. Revenue Recognition (ASC 605) The FASB issued new guidance to help determine separate units of accounting for multiple-deliverables within a single contract that was effective beginning January 1, 2011 for PHI. The energy services contracts of Pepco Energy Services are primarily impacted by this guidance because they often have multiple elements, which could include design, installation, operation and maintenance and measurement and verification services. PHI and its subsidiaries adopted the new guidance, effective January 1, 2011, and it did not have a material impact on Pepco Energy Services' revenue recognition methods or results of operations nor did it have a material impact on PHI's overall financial condition, results of operations or cash flows.
Potomac Electric Power Co [Member]
Newly Adopted Accounting Standards	(3) NEWLY ADOPTED ACCOUNTING STANDARDS Fair Value Measurements and Disclosures (Accounting Standards Codification (ASC) 820) The Financial Accounting Standards Board (FASB) issued new disclosure requirements that require significant items within the reconciliation of the Level 3 valuation category to be presented in separate categories for purchases, sales, issuances and settlements. The guidance was effective beginning with Pepco's March 31, 2011 financial statements. Pepco has included the new disclosure requirements in Note (9), "Fair Value Disclosures," to its financial statements.
Delmarva Power & Light Co/De [Member]
Newly Adopted Accounting Standards	(3) NEWLY ADOPTED ACCOUNTING STANDARDS Fair Value Measurements and Disclosures (Accounting Standards Codification (ASC) 820) The FASB issued new disclosure requirements that require significant items within the reconciliation of the Level 3 valuation category to be presented in separate categories for purchases, sales, issuances and settlements. The guidance was effective beginning with DPL's March 31, 2011 financial statements. DPL has included the new disclosure requirements in Note (11), "Fair Value Disclosures," to its financial statements. Goodwill (ASC 350) The FASB issued new guidance on performing goodwill impairment tests that was effective beginning January 1, 2011 for DPL. Under the new guidance, the carrying value of the reporting unit must include the liabilities that are part of the capital structure of the reporting unit. DPL already allocates liabilities to the reporting unit when performing its goodwill impairment test, so the new guidance did not change DPL's goodwill impairment test methodology.
Atlantic City Electric Co [Member]
Newly Adopted Accounting Standards	(3) NEWLY ADOPTED ACCOUNTING STANDARDS Fair Value Measurements and Disclosures (Accounting Standards Codification (ASC) 820) The FASB issued new disclosure requirements that require significant items within the reconciliation of the Level 3 valuation category to be presented in separate categories for purchases, sales, issuances and settlements. The guidance was effective beginning with ACE's March 31, 2011 financial statements. ACE has included the new disclosure requirements in Note (10), "Fair Value Disclosures," to its financial statements.