Organization and Basis of Presentation (Schedule of Excise Taxes) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	$ 91	$ 87	$ 182	$ 178
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	9	7	18	15
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	55	50	101	96
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	4	4	9	9
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	51	46	92	87
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	23	22	51	51
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	3	$ 8	10	16
Piedmont Natural Gas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	$ 1		$ 2	$ 1