Summary of Significant Accounting Policies (Excise Taxes)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 362	$ 396	$ 498
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	31	31	94
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	213	229	263
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	18	16	56
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	195	213	207
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	100	102	103
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes	$ 17	$ 34	$ 38