Summary of Significant Accounting Policies (Unbilled Revenues)(Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	$ 831	$ 677
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	313	283
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	161	172
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	102	102
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	59	70
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	2	3
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	32	31
Cinergy Receivables [Member] | Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	97	71
Cinergy Receivables [Member] | Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Unbilled receivables	$ 123	$ 97