Fair Value (Nonrecurring Measurements) (Details) - USD ($)		3 Months Ended		12 Months Ended
		Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Oct. 01, 2015	Sep. 30, 2015	Aug. 28, 2015	Jun. 30, 2015	Feb. 09, 2015	Sep. 30, 2014	Sep. 25, 2014	Jun. 30, 2014	Jun. 06, 2014	Feb. 28, 2014
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges				$ 602,000,000	$ 383,000,000	$ 661,000,000
Other non-operating expense				0	128,000,000	129,000,000
Goodwill impairment expense				317,000,000	164,000,000	$ 372,000,000
East Bend DPL [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring				2,000,000
UK Wind (Newfield) [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring														$ 0
UK Wind Development Projects [Domain]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring										$ 1,000,000
Kilroot [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring									$ 70,000,000
buffalo gap III [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring								$ 118,000,000
DPLER
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment expense			$ 136,000,000
Buffalo Gap
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment expense		$ 10,000,000	18,000,000
Fair Value | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring				217,000,000
Fair Value | Long Lived Assets Held And Used [Member] | Ebute [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]							36,000,000
Fair Value | Long Lived Assets Held And Used [Member] | Kilroot [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring									70,000,000
Fair Value | Long Lived Assets Held And Used [Member] | buffalo gap III [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]							118,000,000
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] | Cameroon businesses
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges	[2]				38,000,000
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] | Carrying Amount | Cameroon businesses
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[2]		372,000,000
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] | Fair Value | Cameroon businesses | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[2]		0
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] | Fair Value | Cameroon businesses | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[2]		334,000,000
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member] | Fair Value | Cameroon businesses | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[2]		0
Equity Method Investments [Member] | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[3]			0
Equity Method Investments [Member] | Entek
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[3],[4]				86,000,000
Equity Method Investments [Member] | Silver Ridge Power [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[3],[4]				42,000,000
Equity Method Investments [Member] | Carrying Amount | Solar Spain [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3]										$ 29,000,000
Equity Method Investments [Member] | Carrying Amount | Entek
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[4]												$ 211,000,000
Equity Method Investments [Member] | Carrying Amount | Silver Ridge Power [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3],[4]													315,000,000
Equity Method Investments [Member] | Fair Value | Solar Spain [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3]										0
Equity Method Investments [Member] | Fair Value | Solar Spain [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3]										0
Equity Method Investments [Member] | Fair Value | Solar Spain [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3]										$ 29,000,000
Equity Method Investments [Member] | Fair Value | Entek | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[4]												0
Equity Method Investments [Member] | Fair Value | Entek | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[4]												125,000,000
Equity Method Investments [Member] | Fair Value | Entek | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[4]												$ 0
Equity Method Investments [Member] | Fair Value | Silver Ridge Power [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3],[4]													0
Equity Method Investments [Member] | Fair Value | Silver Ridge Power [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3],[4]													0
Equity Method Investments [Member] | Fair Value | Silver Ridge Power [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3],[4]													273,000,000
Long Lived Assets Held And Used [Member] | Fair Value Measurement [Domain] | Ebute [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[1]				15,000,000
Long Lived Assets Held And Used [Member] | East Bend DPL [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[1]				12,000,000
Long Lived Assets Held And Used [Member] | Ebute [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[1]				52,000,000
Long Lived Assets Held And Used [Member] | UK Wind (Newfield) [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[1]				12,000,000
Long Lived Assets Held And Used [Member] | UK Wind Development Projects [Domain]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[1]			37,000,000
Long Lived Assets Held And Used [Member] | Kilroot [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[1]			121,000,000
Long Lived Assets Held And Used [Member] | buffalo gap III [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[1]			116,000,000
Long Lived Assets Held And Used [Member] | Other Affiliates [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense				11,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount | East Bend DPL [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]		14,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount | Ebute [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]											$ 51,000,000		99,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount | UK Wind (Newfield) [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]														$ 12,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount | UK Wind Development Projects [Domain]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]									38,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount | Kilroot [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]								191,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount | buffalo gap III [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]							234,000,000
Long Lived Assets Held And Used [Member] | Carrying Amount | Other Affiliates [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring				32,000,000
Long Lived Assets Held And Used [Member] | Fair Value | East Bend DPL [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]		0
Long Lived Assets Held And Used [Member] | Fair Value | East Bend DPL [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]		2,000,000
Long Lived Assets Held And Used [Member] | Fair Value | East Bend DPL [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]		0
Long Lived Assets Held And Used [Member] | Fair Value | Ebute [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]											0		0
Long Lived Assets Held And Used [Member] | Fair Value | Ebute [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]											0		0
Long Lived Assets Held And Used [Member] | Fair Value | Ebute [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]											$ 36,000,000		$ 47,000,000
Long Lived Assets Held And Used [Member] | Fair Value | UK Wind (Newfield) [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]														0
Long Lived Assets Held And Used [Member] | Fair Value | UK Wind (Newfield) [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]														0
Long Lived Assets Held And Used [Member] | Fair Value | UK Wind (Newfield) [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]														$ 0
Long Lived Assets Held And Used [Member] | Fair Value | UK Wind Development Projects [Domain] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]									0
Long Lived Assets Held And Used [Member] | Fair Value | UK Wind Development Projects [Domain] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]									1,000,000
Long Lived Assets Held And Used [Member] | Fair Value | Kilroot [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]								0
Long Lived Assets Held And Used [Member] | Fair Value | Kilroot [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]								0
Long Lived Assets Held And Used [Member] | Fair Value | Kilroot [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]								$ 70,000,000
Long Lived Assets Held And Used [Member] | Fair Value | buffalo gap III [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]							0
Long Lived Assets Held And Used [Member] | Fair Value | buffalo gap III [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]							0
Long Lived Assets Held And Used [Member] | Fair Value | Other Affiliates [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring				0
Long Lived Assets Held And Used [Member] | Fair Value | Other Affiliates [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring				21,000,000
Long Lived Assets Held And Used [Member] | Fair Value | Other Affiliates [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring				0
Long Lived Assets Held And Used [Member] | Fair Value | Long Lived Assets Held And Used [Member] | UK Wind Development Projects [Domain] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[1]									$ 0
Long Lived Assets Held And Used [Member] | Fair Value | Long Lived Assets Held And Used [Member] | buffalo gap III [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring								$ 118,000,000
Goodwill [Member] | DPLER
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment expense	[5]				136,000,000
Goodwill [Member] | Buffalo Gap
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment expense	[5]				$ 28,000,000
Goodwill [Member] | DP&L [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense	[3]			$ 317,000,000
Goodwill [Member] | Carrying Amount | DPLER
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[5]															$ 136,000,000
Goodwill [Member] | Carrying Amount | Buffalo Gap
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[5]		28,000,000
Goodwill [Member] | Carrying Amount | DP&L [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3]						$ 317,000,000
Goodwill [Member] | Fair Value | DPLER | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[5]															0
Goodwill [Member] | Fair Value | DPLER | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[5]															0
Goodwill [Member] | Fair Value | DPLER | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[5]															$ 0
Goodwill [Member] | Fair Value | Buffalo Gap | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[5]		0
Goodwill [Member] | Fair Value | Buffalo Gap | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[5]		0
Goodwill [Member] | Fair Value | Buffalo Gap | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[5]		$ 0
Goodwill [Member] | Fair Value | DP&L [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3]						0
Goodwill [Member] | Fair Value | DP&L [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3]						0
Goodwill [Member] | Fair Value | DP&L [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset fair value nonrecurring	[3]						$ 0

[1] (1) See Note 21—Asset Impairment Expense for further information.

[2] (2) See Note 23—Discontinued Operations for further information. Fair value of long-lived assets held-for-sale is presented net of costs to sell.

[3] (3) See Note 8—Investments In and Advances to Affiliates for further information.

[4] (4) See Note 9—Other Non-Operating Expense for further information.

[5] (5) See Note 10—Goodwill and Other Intangible Assets for further information.