Business Segments (Net Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Segment Reporting Information [Line Items]
Segment income	$ 888		$ 942		$ 2,356		$ 1,890
Other [Member]
Segment Reporting Information [Line Items]
Segment income	(92)	[1]	(64)	[1]	(269)	[1]	(278)	[1]
Duke Energy Carolinas [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(19)		(26)		(67)		(69)
Progress Energy [Member]
Segment Reporting Information [Line Items]
Segment income	329		327		739		467
Progress Energy [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(48)		(72)		(145)		(205)
Duke Energy Progress [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(10)		(20)		(23)		(40)
Duke Energy Florida [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	(5)		(6)		(16)		(18)
Duke Energy Indiana [Member] | Other [Member]
Segment Reporting Information [Line Items]
Segment income	$ (3)		$ (5)		$ (10)		$ (13)

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