Fair Value (Nonrecurring Measurements) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Impairment expenses	$ 8		$ 166
Goodwill impairment expense	0		154
East Bend DPL [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			2
DPLER [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment expense			136
Buffalo Gap [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment expense			18
Long Lived Assets Held And Used [Member] | East Bend DPL [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Impairment expenses			12	[1]
Long Lived Assets Held And Used [Member] | Other Affiliates [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Total other non-operating expense	8	[1]
Discontinued operations and held for sale businesses [Member] | Cameroon [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Impairment expenses			38	[2]
Equity Method Investee [Member] | DPLER [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Total other non-operating expense			136	[3]
Equity Method Investee [Member] | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Total other non-operating expense	0
Goodwill [Member] | Buffalo Gap [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment expense			18	[3]
Fair Value [Member] | Long Lived Assets Held And Used [Member] | East Bend DPL [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[1]
Fair Value [Member] | Long Lived Assets Held And Used [Member] | East Bend DPL [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			2	[1]
Fair Value [Member] | Long Lived Assets Held And Used [Member] | East Bend DPL [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[1]
Fair Value [Member] | Long Lived Assets Held And Used [Member] | Other Affiliates [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0	[1]
Fair Value [Member] | Long Lived Assets Held And Used [Member] | Other Affiliates [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	21	[1]
Fair Value [Member] | Long Lived Assets Held And Used [Member] | Other Affiliates [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0	[1]
Fair Value [Member] | Discontinued operations and held for sale businesses [Member] | Cameroon [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[2]
Fair Value [Member] | Discontinued operations and held for sale businesses [Member] | Cameroon [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			334	[2]
Fair Value [Member] | Discontinued operations and held for sale businesses [Member] | Cameroon [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[2]
Fair Value [Member] | Equity Method Investee [Member] | DPLER [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[3]
Fair Value [Member] | Equity Method Investee [Member] | DPLER [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[3]
Fair Value [Member] | Equity Method Investee [Member] | DPLER [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[3]
Fair Value [Member] | Equity Method Investee [Member] | Buffalo Gap [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[3]
Fair Value [Member] | Equity Method Investee [Member] | Buffalo Gap [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			0	[3]
Fair Value [Member] | Equity Method Investee [Member] | Buffalo Gap [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			10	[3]
Fair Value [Member] | Equity Method Investee [Member] | Solar Spain [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0
Fair Value [Member] | Equity Method Investee [Member] | Solar Spain [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0
Fair Value [Member] | Equity Method Investee [Member] | Solar Spain [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	29
Carrying Amount [Member] | Long Lived Assets Held And Used [Member] | East Bend DPL [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			14	[1],[4]
Carrying Amount [Member] | Discontinued operations and held for sale businesses [Member] | Cameroon [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			372	[2],[4]
Carrying Amount [Member] | Equity Method Investee [Member] | DPLER [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			136	[3],[4]
Carrying Amount [Member] | Equity Method Investee [Member] | Other Affiliates [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	29	[1],[4]
Carrying Amount [Member] | Equity Method Investee [Member] | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	29	[4]
Carrying Amount [Member] | Goodwill [Member] | Buffalo Gap [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			$ 28	[3],[4]
Discounted Cash Flow [Member] | Minimum [Member] | Equity Method Investee [Member] | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Annual Revenue Growth Input	(3.00%)
Pretax Operating Margin Input	(13.00%)
Fair Value Inputs, Cost of Equity	0.00%
Discounted Cash Flow [Member] | Maximum [Member] | Equity Method Investee [Member] | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Annual Revenue Growth Input	0.00%
Pretax Operating Margin Input	56.00%
Fair Value Inputs, Cost of Equity	0.00%
Discounted Cash Flow [Member] | Weighted Average [Member] | Equity Method Investee [Member] | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Annual Revenue Growth Input	0.00%
Pretax Operating Margin Input	24.00%
Fair Value Inputs, Cost of Equity	12.00%

[1] See Note 15—Asset Impairment Expense for further information.

[2] See Note 16—Discontinued Operations and Held-For-Sale Businesses for further information.

[3] See Note 14—Goodwill Impairment for further information.

[4] (1) Represents the carrying value (including costs to sell) at the date of measurement, before fair value adjustment.