Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	$ 349	$ 324
Net amounts recognized on the Condensed Consolidated Balance Sheet	349	324
Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	57	64
Gross amounts offset		(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	57	61
Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	292	260
Gross amounts offset	(4)	(5)
Net amounts recognized on the Condensed Consolidated Balance Sheet	288	255
Duke Energy Carolinas
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		20
Net amounts recognized on the Condensed Consolidated Balance Sheet		20
Duke Energy Carolinas | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		17
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet		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	28	29
Net amounts recognized on the Condensed Consolidated Balance Sheet	28	29
Progress Energy | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	3	2
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	3
Progress Energy | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	25	27
Gross amounts offset	(4)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet	21	23
Duke Energy Progress
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	9	14
Net amounts recognized on the Condensed Consolidated Balance Sheet	9	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	9	12
Gross amounts offset	(4)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	8
Duke Energy Florida
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	3
Duke Energy Florida | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	3
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	148	122
Net amounts recognized on the Condensed Consolidated Balance Sheet	148	122
Piedmont | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	19	15
Net amounts recognized on the Condensed Consolidated Balance Sheet	19	15
Piedmont | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	129	107
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 129	$ 107