Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	$ 423	$ 324
Net amounts recognized on the Condensed Consolidated Balance Sheet	423	324
Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	91	64
Gross amounts offset		(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	91	61
Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	332	260
Gross amounts offset	(4)	(5)
Net amounts recognized on the Condensed Consolidated Balance Sheet	328	255
Duke Energy Carolinas
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	7	20
Net amounts recognized on the Condensed Consolidated Balance Sheet	7	20
Duke Energy Carolinas | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	7	17
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	7	15
Duke Energy Carolinas | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		3
Gross amounts offset		(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet		2
Progress Energy
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	17	29
Net amounts recognized on the Condensed Consolidated Balance Sheet	17	29
Progress Energy | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	13	2
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	13
Progress Energy | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	4	27
Gross amounts offset	(4)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet		23
Duke Energy Progress
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	4	14
Net amounts recognized on the Condensed Consolidated Balance Sheet	4	14
Duke Energy Progress | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		2
Gross amounts offset		(2)
Duke Energy Progress | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	4	12
Gross amounts offset	(4)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet		8
Duke Energy Florida
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	13
Net amounts recognized on the Condensed Consolidated Balance Sheet	13
Duke Energy Florida | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	13
Net amounts recognized on the Condensed Consolidated Balance Sheet	13
Duke Energy Ohio
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	5	6
Duke Energy Ohio | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	1	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	1
Duke Energy Ohio | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	4	5
Net amounts recognized on the Condensed Consolidated Balance Sheet	4	5
Duke Energy Indiana
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		1
Net amounts recognized on the Condensed Consolidated Balance Sheet		1
Duke Energy Indiana | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		1
Net amounts recognized on the Condensed Consolidated Balance Sheet		1
Piedmont
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	161	122
Net amounts recognized on the Condensed Consolidated Balance Sheet	161	122
Piedmont | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	26	15
Net amounts recognized on the Condensed Consolidated Balance Sheet	26	15
Piedmont | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	135	107
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 135	$ 107