Commitments And Contingencies (Third Party Guarantees, Indemnifications, And Off-Balance Sheet Arrangements) (Details) (USD $) In Millions	Sep. 30, 2011
Energy procurement obligations of Pepco Energy Services	$ 170	[1]
Guarantees associated with disposal of Conectiv Energy assets	28	[2]
Guaranteed lease residual values	13	[3]
Total	211
Guaranteed amounts on transferred tolling agreements	15
Derivative portfolio guarantee	13
Obligations under guarantees	13
PHI [Member]
Energy procurement obligations of Pepco Energy Services	170	[1]
Guarantees associated with disposal of Conectiv Energy assets	28	[2]
Guaranteed lease residual values	2	[3]
Total	200
Delmarva Power & Light Co/De [Member]
Guaranteed lease residual values	5	[3]
Total	5
ACE [Member]
Guaranteed lease residual values	3	[3]
Total	3
Pepco [Member]
Guaranteed lease residual values	3	[3]
Total	$ 3

[1] Pepco Holdings has contractual commitments for performance and related payments of Pepco Energy Services to counterparties under routine energy sales and procurement obligations.

[2] Represents guarantees by PHI in connection with transfers of Conectiv Energy tolling agreements and derivatives portfolio. The tolling agreement guarantees cover the payment by the entity to which the tolling agreement was assigned. The guaranteed amounts on the transferred tolling agreements totaled $15 million at September 30, 2011, which decline until the termination of the guarantees. The derivative portfolio guarantee is currently $13 million and covers Conectiv Energy's performance prior to the assignment. This guarantee will remain in effect until the end of 2015.

[3] Subsidiaries of Pepco Holdings have guaranteed residual values in excess of fair value of certain equipment and fleet vehicles held through lease agreements. As of September 30, 2011, obligations under the guarantees were approximately $13 million. Assets leased under agreements subject to residual value guarantees are typically for periods ranging from 2 years to 10 years. Historically, payments under the guarantees have not been made by the guarantor as, under normal conditions, the contract runs to full term at which time the residual value is immaterial. As such, Pepco Holdings believes the likelihood of payments being required under the guarantee is remote.