Fair Value Disclosures (Fair Value Of Assets And Liabilities Measured On Recurring Basis) (Details) (USD $) In Millions	Jun. 30, 2011		Dec. 31, 2010
Derivative instruments, assets	$ 153		$ 114
Derivative instruments, liabilities	153		216
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member]
Derivative instruments, assets	78	[1]	26	[1]
Derivative instruments, liabilities	47	[1]	75	[1]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Treasury Fund [Member]
Cash equivalents	62	[1]	17	[1]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Money Market Funds [Member]
Executive deferred compensation plan assets	16	[1]	9	[1]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Natural Gas [Member]
Derivative instruments, liabilities	47	[1],[2]	75	[1],[2]
Significant Other Observable Inputs (Level 2) [Member]
Derivative instruments, assets	56	[1]	69	[1]
Derivative instruments, liabilities	85	[1]	118	[1]
Significant Other Observable Inputs (Level 2) [Member] | Electricity [Member]
Derivative instruments, assets	11	[1],[3]	22	[1],[3]
Derivative instruments, liabilities	55	[1],[3]	88	[1],[3]
Significant Other Observable Inputs (Level 2) [Member] | Life Insurance Contracts [Member]
Executive deferred compensation plan assets	45	[1]	47	[1]
Executive deferred compensation plan liabilities	30	[1]	30	[1]
Significant Unobservable Inputs (Level 3) [Member]
Derivative instruments, assets	19		19
Derivative instruments, liabilities	21		23
Significant Unobservable Inputs (Level 3) [Member] | Natural Gas [Member]
Derivative instruments, liabilities	21	[2]	23	[2]
Significant Unobservable Inputs (Level 3) [Member] | Life Insurance Contracts [Member]
Executive deferred compensation plan assets	19		19
Electricity [Member]
Derivative instruments, assets	11	[3]	22	[3]
Derivative instruments, liabilities	55	[3]	88	[3]
Treasury Fund [Member]
Cash equivalents	62		17
Money Market Funds [Member]
Executive deferred compensation plan assets	16		9
Natural Gas [Member]
Derivative instruments, liabilities	68	[2]	98	[2]
Life Insurance Contracts [Member]
Executive deferred compensation plan assets	64		66
Executive deferred compensation plan liabilities	$ 30		$ 30

[1] There were no significant transfers of instruments between level 1 and level 2 valuation categories.

[2] Level 1 instruments represent wholesale gas futures and swaps that are used mainly as part of Pepco Energy Service's retail energy supply business and level 3 instruments represent natural gas options purchased by DPL as part of a natural gas hedging program approved by the DPSC.

[3] Represents wholesale electricity futures and swaps that are used mainly as part of Pepco Energy Service's retail energy supply business.