Committments and Contingencies (Schedule of Reserves and Insurance Recoveries) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Reserves for legal matters	$ 975	[1],[2]	$ 810	[1],[2]
Probable insurance recoveries	781	[3],[4]	813	[3],[4]
Duke Energy Carolinas [Member]
Reserves for legal matters	763	[1],[2]	801	[1],[2]
Probable insurance recoveries	781	[3],[4]	813	[3],[4]
Duke Energy Indiana [Member]
Reserves for legal matters	$ 7	[1]	$ 4	[1]

[1] Reserves are classified in the respective Condensed Consolidated Balance Sheets in Other within Deferred Credits and Other Liabilities and Other within Current Liabilities.

[2] Includes reserves for aforementioned asbestos-related injuries and damages claims.

[3] Insurance recoveries are classified in the respective Condensed Consolidated Balance Sheets in Other within Investments and Other Assets and Receivables.

[4] Relates to recoveries associated with aforementioned asbestos-related injuries and damages claims.