Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	$ 359	$ 300
Net amounts recognized on the Condensed Consolidated Balance Sheet	359	277
Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	84	118
Gross amounts offset	(1)	(24)
Net amounts recognized on the Condensed Consolidated Balance Sheet	83	94
Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	275	182
Gross amounts offset	(8)
Net amounts recognized on the Condensed Consolidated Balance Sheet	267	182
Duke Energy Carolinas
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	33	49
Net amounts recognized on the Condensed Consolidated Balance Sheet	33	49
Duke Energy Carolinas | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	29	39
Net amounts recognized on the Condensed Consolidated Balance Sheet	29	39
Duke Energy Carolinas | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	4	10
Net amounts recognized on the Condensed Consolidated Balance Sheet	4	10
Progress Energy
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	36	88
Net amounts recognized on the Condensed Consolidated Balance Sheet	36	65
Progress Energy | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	9	51
Gross amounts offset		(24)
Net amounts recognized on the Condensed Consolidated Balance Sheet	9	27
Progress Energy | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	27	37
Gross amounts offset	(8)
Net amounts recognized on the Condensed Consolidated Balance Sheet	19	37
Duke Energy Progress
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	20	49
Net amounts recognized on the Condensed Consolidated Balance Sheet	20	49
Duke Energy Progress | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	9	27
Net amounts recognized on the Condensed Consolidated Balance Sheet	9	27
Duke Energy Progress | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	11	22
Gross amounts offset	(8)
Net amounts recognized on the Condensed Consolidated Balance Sheet	3	22
Duke Energy Florida
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		24
Net amounts recognized on the Condensed Consolidated Balance Sheet		1
Duke Energy Florida | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		24
Gross amounts offset		(24)
Duke Energy Ohio
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	7	6
Duke Energy Ohio | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	2	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	1
Duke Energy Ohio | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	5	5
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	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 Natural Gas
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	111	117
Net amounts recognized on the Condensed Consolidated Balance Sheet	111	117
Piedmont Natural Gas | Current liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	13	7
Net amounts recognized on the Condensed Consolidated Balance Sheet	13	7
Piedmont Natural Gas | Noncurrent liabilities
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	98	110
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 98	$ 110