Fair Value (Nonrecurring Measurements) (Details) - USD ($)		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Mar. 31, 2016	Feb. 09, 2015
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges				$ 396,000,000	$ 45,000,000
Other Asset Impairment Charges		$ 235,000,000	$ 37,000,000	394,000,000	45,000,000
UK Wind Projects [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring			1,000,000		1,000,000
Discontinued operations and held for sale businesses [Member] | Sul Subsidiary [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other Asset Impairment Charges	[1]			783,000,000
Discontinued operations and held for sale businesses [Member] | Fair Value [Member] | Sul Subsidiary [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[1]	0		0
Discontinued operations and held for sale businesses [Member] | Fair Value [Member] | Sul Subsidiary [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[1]	470,000,000		470,000,000
Discontinued operations and held for sale businesses [Member] | Carrying Amount [Member] | Sul Subsidiary [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[1],[2]	1,581,000,000		1,581,000,000
Long Lived Assets Held And Used [Member] | DPL Subsidiary [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other Asset Impairment Charges	[3]			235,000,000
Long Lived Assets Held And Used [Member] | buffalo gap II [Member] [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring						$ 92,000,000
Other Asset Impairment Charges	[3]			159,000,000
Long Lived Assets Held And Used [Member] | UK Wind Projects [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges	[3]				37,000,000
Long Lived Assets Held And Used [Member] | Other Entity [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other Asset Impairment Charges	[3]				8,000,000
Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]	0		0
Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]	0		0
Long Lived Assets Held And Used [Member] | Fair Value [Member] | buffalo gap II [Member] [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]					0
Long Lived Assets Held And Used [Member] | Fair Value [Member] | buffalo gap II [Member] [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]					0
Long Lived Assets Held And Used [Member] | Fair Value [Member] | UK Wind Projects [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]		0		0
Long Lived Assets Held And Used [Member] | Fair Value [Member] | UK Wind Projects [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]		1,000,000		1,000,000
Long Lived Assets Held And Used [Member] | Fair Value [Member] | UK Wind Projects [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]		0		0
Long Lived Assets Held And Used [Member] | Fair Value [Member] | Other Entity [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]		0		0
Long Lived Assets Held And Used [Member] | Fair Value [Member] | Other Entity [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]		21,000,000		21,000,000
Long Lived Assets Held And Used [Member] | Fair Value [Member] | Other Entity [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]		0		0
Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | DPL Subsidiary [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[2],[3]	324,000,000		324,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | buffalo gap II [Member] [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[2],[3]					251,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | UK Wind Projects [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[2],[3]		38,000,000		38,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount [Member] | Other Entity [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[2],[3]		$ 29,000,000		29,000,000
Equity Method Investments [Member] | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other Nonoperating Expense					$ 0
Equity Method Investments [Member] | Fair Value [Member] | Solar Spain [Member] | Level 1 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring							$ 0
Equity Method Investments [Member] | Fair Value [Member] | Solar Spain [Member] | Level 2 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring							0
Equity Method Investments [Member] | Fair Value [Member] | Solar Spain [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring							29,000,000
Equity Method Investments [Member] | Carrying Amount [Member] | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[2]						$ 29,000,000
Discontinued Operations, Held-for-sale [Member] | Discontinued operations and held for sale businesses [Member] | Fair Value [Member] | Sul Subsidiary [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[1]	0		0
Long Lived Assets Held And Used [Member] | buffalo gap II [Member] [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]					$ 92,000,000
Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	[3]	89,000,000		89,000,000
Long Lived Assets Held And Used [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | DPL Subsidiary [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		89,000,000		89,000,000
Long Lived Assets Held And Used [Member] | Long Lived Assets Held And Used [Member] | Fair Value [Member] | buffalo gap II [Member] [Member] | Level 3 [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		$ 92,000,000		$ 92,000,000
Long Lived Assets Held And Used [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member] | DPL Subsidiary [Member]
Fair Value Assets Measured On Nonrecurring Basis Unobservable Inputs [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate				(10.00%)
Fair Value Inputs, Long-term Pre-tax Operating Margin, Percent				(5.00%)
Long Lived Assets Held And Used [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member] | buffalo gap II [Member] [Member]
Fair Value Assets Measured On Nonrecurring Basis Unobservable Inputs [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate				20.00%
Fair Value Inputs, Long-term Pre-tax Operating Margin, Percent				18.00%
Fair Value Inputs, Discount Rate				9.00%
Long Lived Assets Held And Used [Member] | Income Approach Valuation Technique [Member] | Maximum [Member] | DPL Subsidiary [Member]
Fair Value Assets Measured On Nonrecurring Basis Unobservable Inputs [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate				13.00%
Fair Value Inputs, Long-term Pre-tax Operating Margin, Percent				60.00%
Fair Value Inputs, Discount Rate				12.00%
Long Lived Assets Held And Used [Member] | Income Approach Valuation Technique [Member] | Maximum [Member] | buffalo gap II [Member] [Member]
Fair Value Assets Measured On Nonrecurring Basis Unobservable Inputs [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate				21.00%
Fair Value Inputs, Long-term Pre-tax Operating Margin, Percent				48.00%
Long Lived Assets Held And Used [Member] | Income Approach Valuation Technique [Member] | Minimum [Member] | DPL Subsidiary [Member]
Fair Value Assets Measured On Nonrecurring Basis Unobservable Inputs [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate				(11.00%)
Fair Value Inputs, Long-term Pre-tax Operating Margin, Percent				(50.00%)
Fair Value Inputs, Discount Rate				(7.00%)
Long Lived Assets Held And Used [Member] | Income Approach Valuation Technique [Member] | Minimum [Member] | buffalo gap II [Member] [Member]
Fair Value Assets Measured On Nonrecurring Basis Unobservable Inputs [Line Items]
Fair Value Inputs, Long-term Revenue Growth Rate				(17.00%)
Fair Value Inputs, Long-term Pre-tax Operating Margin, Percent				(166.00%)

[1] (3) Per the Company’s policy, pre-tax loss is limited to the impairment of long-lived assets. Any additional loss will be recognized on completion of the sale. See Note 15—Discontinued Operations and Held-for-Sale Businesses for further information.

[2] (1) Represents the carrying values at the dates of measurement, before fair value adjustment.

[3] See Note 13—Asset Impairment Expense for further information.