Fair Value Disclosures (Fair Value Of Financial Assets And Liabilities Measured On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, assets	$ 150		$ 192
Derivative instruments, liabilities	115		128
Electricity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, assets	3	[1],[2]
Derivative instruments, liabilities	31	[1],[2]	32	[2],[3]
Treasury Fund [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	70		114
Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Executive deferred compensation plan assets	16		18
Natural Gas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, liabilities	56	[1],[4]	67	[3],[5]
Capacity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, liabilities			1	[3]
Life Insurance Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Executive deferred compensation plan assets	61		60
Executive deferred compensation plan liabilities	28		28
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, assets	86	[6]	132	[6]
Derivative instruments, liabilities	42	[6]	50	[6]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Treasury Fund [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	70	[6]	114	[6]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Money Market Funds [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Executive deferred compensation plan assets	16	[6]	18	[6]
Quoted Prices In Active Markets For Identical Instruments (Level 1) [Member] | Natural Gas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, liabilities	42	[1],[4],[6]	50	[3],[5],[6]
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, assets	46	[6]	43	[6]
Derivative instruments, liabilities	59	[6]	61	[6]
Significant Other Observable Inputs (Level 2) [Member] | Electricity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, assets	3	[1],[2],[6]
Derivative instruments, liabilities	31	[1],[2],[6]	32	[2],[3],[6]
Significant Other Observable Inputs (Level 2) [Member] | Capacity [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, liabilities			1	[3],[6]
Significant Other Observable Inputs (Level 2) [Member] | Life Insurance Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Executive deferred compensation plan assets	43	[6]	43	[6]
Executive deferred compensation plan liabilities	28	[6]	28	[6]
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, assets	18		17
Derivative instruments, liabilities	14		17
Significant Unobservable Inputs (Level 3) [Member] | Natural Gas [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Derivative instruments, liabilities	14	[1],[4]	17	[3],[5]
Significant Unobservable Inputs (Level 3) [Member] | Life Insurance Contracts [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Executive deferred compensation plan assets	$ 18		$ 17

[1] The fair value of derivative assets and liabilities reflect netting by counterparty before the impact of collateral.

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

[3] The fair value of derivative liabilities reflect netting by counterparty before the impact of collateral.

[4] Level 1 instruments represent wholesale gas futures and swaps that are used mainly as part of Pepco Energy Services' 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, as well as Pepco Energy Services physical basis contracts.

[5] Level 1 instruments represent wholesale gas futures and swaps that are used mainly as part of Pepco Energy Services' 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.

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