Business Segments (Net Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Segment Reporting Information [Line Items]
Segment income	$ 612		$ 342		$ 518		$ 976
Other Segments [Member]
Segment Reporting Information [Line Items]
Segment income	(103)	[1]	(139)	[1]	(185)	[1]	(216)	[1]
Duke Energy Carolinas [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Segment income	(27)		(25)		(48)		(43)
Progress Energy [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Segment income	(45)		(55)		(97)		(133)
Duke Energy Progress [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Segment income	(3)		(14)		(13)		(20)
Duke Energy Florida [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Segment income	(7)		(7)		(11)		(12)
Duke Energy Indiana [Member] | Other Segments [Member]
Segment Reporting Information [Line Items]
Segment income	$ (4)		$ (4)		$ (7)		$ (8)

[1] Other includes costs to achieve the Progress Energy merger.