Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 543	$ 61
Net amounts recognized on the Condensed Consolidated Balance Sheet	543	61
Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	363	48
Gross amounts offset	(143)	(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	220	45
Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	180	13
Gross amounts offset	(71)	(5)
Net amounts recognized on the Condensed Consolidated Balance Sheet	109	8
Duke Energy Carolinas
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	271	20
Net amounts recognized on the Condensed Consolidated Balance Sheet	271	20
Duke Energy Carolinas | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	171	14
Gross amounts offset	(87)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	84	12
Duke Energy Carolinas | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	100	6
Gross amounts offset	(45)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	55	5
Progress Energy
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	215	33
Net amounts recognized on the Condensed Consolidated Balance Sheet	215	33
Progress Energy | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	137	27
Gross amounts offset	(56)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	81	25
Progress Energy | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	78	6
Gross amounts offset	(26)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet	52	2
Duke Energy Progress
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	215	33
Net amounts recognized on the Condensed Consolidated Balance Sheet	215	33
Duke Energy Progress | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	137	27
Gross amounts offset	(56)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	81	25
Duke Energy Progress | Noncurrent assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	78	6
Gross amounts offset	(26)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet	52	2
Duke Energy Ohio
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	4	1
Duke Energy Ohio | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	4	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	4	1
Duke Energy Indiana
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	36	6
Net amounts recognized on the Condensed Consolidated Balance Sheet	36	6
Duke Energy Indiana | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	36	6
Net amounts recognized on the Condensed Consolidated Balance Sheet	36	6
Piedmont
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	12	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	12	1
Piedmont | Current assets
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	12	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 12	$ 1