Committments and Contingencies (Schedule of Reserves and Insurance Recoveries) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Loss Contingencies [Line Items]
Reserves for legal matters	$ 834	[1],[2]	$ 846	[1],[2]
Probable insurance recoveries	781	[3],[4]	781	[3],[4]
Duke Energy Carolinas [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	743	[1],[2]	751	[1],[2]
Probable insurance recoveries	781	[3],[4]	781	[3],[4]
Progress Energy [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	75	[1]	79	[1]
Duke Energy Progress [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	11	[1]	12	[1]
Duke Energy Florida [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	44	[1],[5]	47	[1],[5]
Duke Energy Indiana [Member]
Loss Contingencies [Line Items]
Reserves for legal matters	$ 7	[1]	$ 8	[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.

[5] Includes workers' compensation claims.