Organization and Basis of Presentation (Schedule of Excise Taxes) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	$ 91	$ 91
Duke Energy Carolinas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	9	8
Progress Energy [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	46	47
Duke Energy Progress [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	5	5
Duke Energy Florida [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	41	42
Duke Energy Ohio [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	28	28
Duke Energy Indiana [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	7	8
Piedmont Natural Gas [Member]
Organization And Basis Of Presentation [Line Items]
Excise taxes collected	$ 1	$ 1