Fair Value (Nonrecurring Measurements) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges	$ 43	$ 130	$ 72	$ 163
Other non-operating expense	0	82	50	82
Goodwill impairment	1,850	17	1,850	17
DP&L [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment	1,850
Long Lived Assets Held And Used [Member] | Kelanitissa [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges			12	37
Long Lived Assets Held And Used [Member] | Wind projects [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges			16
Long Lived Assets Held And Used [Member] | Wind turbines and deposits [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges				116
Long Lived Assets Held And Used [Member] | Bohemia [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges				9
Long Lived Assets Held For Sale [Member] | Wind Turbines [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges			20
Long Lived Assets Held For Sale [Member] | St Patrick [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges			11
Long Lived Assets Held For Sale [Member] | Carbon Reduction Projects [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Asset Impairment Charges				33
Equity Method Affiliate [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense			50
Equity Method Affiliate [Member] | Yangcheng [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Other non-operating expense				74
Goodwill [Member] | DP&L [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment			1,850
Goodwill [Member] | Chigen [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Goodwill impairment				17
Carrying Amount | Long Lived Assets Held And Used [Member] | Kelanitissa [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	22	66	22	66
Carrying Amount | Long Lived Assets Held And Used [Member] | Wind projects [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	16		16
Carrying Amount | Long Lived Assets Held And Used [Member] | Wind turbines and deposits [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		161		161
Carrying Amount | Long Lived Assets Held And Used [Member] | Bohemia [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		14		14
Carrying Amount | Long Lived Assets Held For Sale [Member] | Wind Turbines [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	45		45
Carrying Amount | Long Lived Assets Held For Sale [Member] | St Patrick [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	33		33
Carrying Amount | Long Lived Assets Held For Sale [Member] | Carbon Reduction Projects [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		49		49
Carrying Amount | Equity Method Affiliate [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	205		205
Carrying Amount | Equity Method Affiliate [Member] | Yangcheng [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		100		100
Carrying Amount | Goodwill [Member] | DP&L [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	2,449		2,449
Carrying Amount | Goodwill [Member] | Chigen [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		17		17
Fair Value | Long Lived Assets Held And Used [Member] | Kelanitissa [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0	0	0	0
Fair Value | Long Lived Assets Held And Used [Member] | Kelanitissa [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0	0	0	0
Fair Value | Long Lived Assets Held And Used [Member] | Kelanitissa [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	10	29	10	29
Fair Value | Long Lived Assets Held And Used [Member] | Wind projects [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Long Lived Assets Held And Used [Member] | Wind projects [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Long Lived Assets Held And Used [Member] | Wind projects [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Long Lived Assets Held And Used [Member] | Wind turbines and deposits [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Long Lived Assets Held And Used [Member] | Wind turbines and deposits [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		45		45
Fair Value | Long Lived Assets Held And Used [Member] | Wind turbines and deposits [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Long Lived Assets Held And Used [Member] | Bohemia [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Long Lived Assets Held And Used [Member] | Bohemia [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		5		5
Fair Value | Long Lived Assets Held And Used [Member] | Bohemia [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Long Lived Assets Held For Sale [Member] | Wind Turbines [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Long Lived Assets Held For Sale [Member] | Wind Turbines [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Long Lived Assets Held For Sale [Member] | Wind Turbines [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	25		25
Fair Value | Long Lived Assets Held For Sale [Member] | St Patrick [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Long Lived Assets Held For Sale [Member] | St Patrick [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	22		22
Fair Value | Long Lived Assets Held For Sale [Member] | St Patrick [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Long Lived Assets Held For Sale [Member] | Carbon Reduction Projects [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Long Lived Assets Held For Sale [Member] | Carbon Reduction Projects [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Long Lived Assets Held For Sale [Member] | Carbon Reduction Projects [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		11		11
Fair Value | Equity Method Affiliate [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Equity Method Affiliate [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	155		155
Fair Value | Equity Method Affiliate [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Equity Method Affiliate [Member] | Yangcheng [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Equity Method Affiliate [Member] | Yangcheng [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Equity Method Affiliate [Member] | Yangcheng [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		26		26
Fair Value | Goodwill [Member] | DP&L [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Goodwill [Member] | DP&L [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	0		0
Fair Value | Goodwill [Member] | DP&L [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring	599		599
Fair Value | Goodwill [Member] | Chigen [Member] | Level 1
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Goodwill [Member] | Chigen [Member] | Level 2
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		0		0
Fair Value | Goodwill [Member] | Chigen [Member] | Level 3
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Fair Value, Nonrecurring		$ 0		$ 0