Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 282	$ 61
Net amounts recognized on the Condensed Consolidated Balance Sheet	282	61
Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	215	48
Gross amounts offset	(3)	(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	212	45
Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	67	13
Gross amounts offset	(6)	(5)
Net amounts recognized on the Condensed Consolidated Balance Sheet	61	8
Duke Energy Carolinas
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	107	20
Net amounts recognized on the Condensed Consolidated Balance Sheet	107	20
Duke Energy Carolinas | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	69	14
Gross amounts offset	(3)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	66	12
Duke Energy Carolinas | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	38	6
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	37	5
Progress Energy
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	142	33
Net amounts recognized on the Condensed Consolidated Balance Sheet	142	33
Progress Energy | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	113	27
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	113	25
Progress Energy | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	29	6
Gross amounts offset	(4)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet	25	2
Duke Energy Progress
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	132	33
Net amounts recognized on the Condensed Consolidated Balance Sheet	132	33
Duke Energy Progress | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	102	27
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	102	25
Duke Energy Progress | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	30	6
Gross amounts offset	(4)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet	26	2
Duke Energy Florida
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	10
Net amounts recognized on the Condensed Consolidated Balance Sheet	10
Duke Energy Florida | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	10
Net amounts recognized on the Condensed Consolidated Balance Sheet	10
Duke Energy Ohio
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	1
Duke Energy Ohio | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	3	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	3	1
Duke Energy Indiana
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	24	6
Net amounts recognized on the Condensed Consolidated Balance Sheet	24	6
Duke Energy Indiana | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	24	6
Net amounts recognized on the Condensed Consolidated Balance Sheet	24	6
Piedmont
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	1
Piedmont | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 2	$ 1