Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 35	$ 57
Net amounts recognized on the Condensed Consolidated Balance Sheet	35	57
Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	18	38
Gross amounts offset	(4)	(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	14	35
Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	17	19
Gross amounts offset	(3)	(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	14	16
Duke Energy Carolinas [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	3
Duke Energy Carolinas [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	2
Gross amounts offset	(2)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	1
Duke Energy Carolinas [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	1
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	1
Progress Energy [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	8	4
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	4
Progress Energy [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	2
Gross amounts offset	(1)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	4
Progress Energy [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	2
Gross amounts offset	(2)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	1
Duke Energy Progress [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	8	4
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	4
Duke Energy Progress [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	2
Gross amounts offset	(1)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	4
Duke Energy Progress [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	2
Gross amounts offset	(2)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	1
Duke Energy Ohio [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	1	6
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	1	6
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	6
Duke Energy Indiana [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	23
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	23
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	23
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	23
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