Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 86	$ 25
Net amounts recognized on the Condensed Consolidated Balance Sheet	86	25
Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	60	24
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	59	23
Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	26	1
Gross amounts offset	(8)
Net amounts recognized on the Condensed Consolidated Balance Sheet	18	1
Duke Energy Carolinas
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	38
Net amounts recognized on the Condensed Consolidated Balance Sheet	38
Duke Energy Carolinas | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	24
Net amounts recognized on the Condensed Consolidated Balance Sheet	24
Duke Energy Carolinas | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	14
Net amounts recognized on the Condensed Consolidated Balance Sheet	14
Progress Energy
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	33	7
Net amounts recognized on the Condensed Consolidated Balance Sheet	33	7
Progress Energy | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	21	7
Gross amounts offset		(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	21	6
Progress Energy | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	12
Gross amounts offset	(8)
Net amounts recognized on the Condensed Consolidated Balance Sheet	4
Duke Energy Progress
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	33
Net amounts recognized on the Condensed Consolidated Balance Sheet	33
Duke Energy Progress | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	21
Net amounts recognized on the Condensed Consolidated Balance Sheet	21
Duke Energy Progress | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	12
Gross amounts offset	(8)
Net amounts recognized on the Condensed Consolidated Balance Sheet	4
Duke Energy Florida
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		7
Net amounts recognized on the Condensed Consolidated Balance Sheet		7
Duke Energy Florida | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		7
Gross amounts offset		(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet		6
Duke Energy Ohio
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	4
Duke Energy Ohio | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	3
Duke Energy Ohio | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		1
Net amounts recognized on the Condensed Consolidated Balance Sheet		1
Duke Energy Indiana
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	8	13
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	13
Duke Energy Indiana | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	8	13
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	13
Piedmont Natural Gas
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	6	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	6	1
Piedmont Natural Gas | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	6	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 6	$ 1