Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data	Jun. 30, 2011	Dec. 31, 2010
Receivables, allowance for doubtful accounts	$ 39	$ 34
Restricted receivables, allowance for doubtful accounts	39	34
Common Stock, par value	$ 0.001	$ 0.001
Common Stock, shares authorized	2,000,000,000	2,000,000,000
Common Stock, shares outstanding	1,332,000,000	1,329,000,000
Duke Energy Carolinas [Member]
Receivables, allowance for doubtful accounts	3	3
Restricted receivables, allowance for doubtful accounts	6	6
Duke Energy Ohio [Member]
Receivables, allowance for doubtful accounts	18	18
Common Stock, par value	$ 8.5	$ 8.5
Common Stock, shares authorized	120,000,000	120,000,000
Common Stock, shares outstanding	89,663,086	89,663,086
Duke Energy Indiana [Member]
Receivables, allowance for doubtful accounts	$ 2	$ 1
Common Stock, par value	$ 0.01	$ 0.01
Common Stock, shares authorized	60,000,000	60,000,000
Common Stock, shares outstanding	53,913,701	53,913,701