Business Segments (Schedule of Segment Reporting Information, by Segment) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Segment income	$ 691	$ 773
Duke Energy Carolinas [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(17)	(8)
Progress Energy [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(49)	(42)
Duke Energy Progress [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(8)	(4)
Duke Energy Florida [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(4)	(3)
Duke Energy Ohio [Member]
Segment Reporting Information [Line Items]
Segment income		59
Duke Energy Ohio [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(9)	(2)
Duke Energy Indiana [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	$ (2)	$ (2)