Organization and Basis of Presentation (Schedule of Unbilled Revenues with Restricted Receivables) (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	$ 748	$ 827
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	247	295
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	220	217
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	123	135
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	97	82
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	6
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	25	27
Cinergy Receivables [Member] | Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	64	79
Cinergy Receivables [Member] | Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	$ 93	$ 112