Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	$ 415	$ 324
Net amounts recognized on the Condensed Consolidated Balance Sheet	415	324
Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	134	64
Gross amounts offset		(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	134	61
Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	281	260
Gross amounts offset		(5)
Net amounts recognized on the Condensed Consolidated Balance Sheet	281	255
Duke Energy Carolinas
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	18	20
Net amounts recognized on the Condensed Consolidated Balance Sheet	18	20
Duke Energy Carolinas | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	18	17
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	18	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	12	29
Net amounts recognized on the Condensed Consolidated Balance Sheet	12	29
Progress Energy | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	12	2
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	12
Progress Energy | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		27
Gross amounts offset		(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet		23
Duke Energy Progress
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		14
Net amounts recognized on the Condensed Consolidated Balance Sheet		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		12
Gross amounts offset		(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet		8
Duke Energy Florida
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	12
Net amounts recognized on the Condensed Consolidated Balance Sheet	12
Duke Energy Florida | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	12
Net amounts recognized on the Condensed Consolidated Balance Sheet	12
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	2	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	1
Duke Energy Indiana | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	2	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	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	20	15
Net amounts recognized on the Condensed Consolidated Balance Sheet	20	15
Piedmont | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	128	107
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 128	$ 107