Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 69	$ 162
Net amounts recognized on the Condensed Consolidated Balance Sheet	69	162
Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	49	111
Gross amounts offset	(3)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	46	100
Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	20	51
Gross amounts offset	(2)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	18	49
Duke Energy Carolinas [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	8	33
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	33
Duke Energy Carolinas [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	6	23
Net amounts recognized on the Condensed Consolidated Balance Sheet	6	23
Duke Energy Carolinas [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	10
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	9
Progress Energy [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	15	85
Net amounts recognized on the Condensed Consolidated Balance Sheet	15	85
Progress Energy [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	11	64
Gross amounts offset	(3)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	53
Progress Energy [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	4	21
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	3	20
Duke Energy Progress [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	8	46
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	46
Duke Energy Progress [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	36
Gross amounts offset	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	4	36
Duke Energy Progress [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	10
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	9
Duke Energy Florida [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	6	39
Net amounts recognized on the Condensed Consolidated Balance Sheet	6	39
Duke Energy Florida [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	28
Gross amounts offset	(2)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	3	17
Duke Energy Florida [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	1	11
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	11
Duke Energy Ohio [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	5
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	5
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	4
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	4
Duke Energy Ohio [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		1
Net amounts recognized on the Condensed Consolidated Balance Sheet		1
Duke Energy Indiana [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	28	16
Net amounts recognized on the Condensed Consolidated Balance Sheet	28	16
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	28	16
Net amounts recognized on the Condensed Consolidated Balance Sheet	28	16
Piedmont Natural Gas [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	3
Piedmont Natural Gas [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 2	$ 3