Goodwill (Details) (USD $) In Millions	3 Months Ended
	Sep. 30, 2011		Dec. 31, 2010
Goodwill [Line Items]
Balance at beginning of period			$ 1,761
Goodwill recognized during the period	2,366	[1]
Effect of foreign currency exchange rates	69
Balance at end of period	4,196		1,761
Kentucky Regulated [Member]
Goodwill [Line Items]
Balance at beginning of period			662	[2]
Goodwill recognized during the period	0
Effect of foreign currency exchange rates	0
Balance at end of period	662	[2]	662	[2]
International Regulated [Member]
Goodwill [Line Items]
Balance at beginning of period			679	[2]
Goodwill recognized during the period	2,366	[1]
Effect of foreign currency exchange rates	69
Balance at end of period	3,114	[2]	679	[2]
Supply [Member]
Goodwill [Line Items]
Balance at beginning of period			420	[2],[3]
Goodwill recognized during the period	0
Effect of foreign currency exchange rates	0
Balance at end of period	$ 420	[2]	$ 420	[2],[3]

[1] Recognized as a result of the 2011 acquisition of WPD Midlands. See Note 8 for additional information.

[2] There were no accumulated impairment losses related to goodwill.

[3] Includes goodwill attributed to the Supply segment as a result of the 2010 acquisition of LKE.