Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	$ 353	$ 242
Net amounts recognized on the Condensed Consolidated Balance Sheet	353	242
Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	142	68
Gross amounts offset	(10)	(4)
Net amounts recognized on the Condensed Consolidated Balance Sheet	132	64
Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	211	174
Gross amounts offset		(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	211	171
Duke Energy Carolinas [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	67	33
Net amounts recognized on the Condensed Consolidated Balance Sheet	67	33
Duke Energy Carolinas [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	55	23
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	55	21
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	12	10
Gross amounts offset		(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	12	9
Progress Energy [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	113	44
Net amounts recognized on the Condensed Consolidated Balance Sheet	113	44
Progress Energy [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	76	23
Gross amounts offset	(10)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	66	21
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	37	21
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	37	19
Duke Energy Progress [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	43	27
Net amounts recognized on the Condensed Consolidated Balance Sheet	43	27
Duke Energy Progress [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	25	16
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	25	14
Duke Energy Progress [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	18	11
Gross amounts offset		(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	18	9
Duke Energy Florida [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	54	9
Net amounts recognized on the Condensed Consolidated Balance Sheet	54	9
Duke Energy Florida [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	51	8
Gross amounts offset	(10)
Net amounts recognized on the Condensed Consolidated Balance Sheet	41	8
Duke Energy Florida [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	3	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	3	1
Duke Energy Ohio [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	6	5
Duke Energy Ohio [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	1	1
Net amounts recognized on the Condensed Consolidated Balance Sheet	1	1
Duke Energy Ohio [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	5	4
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	4
Piedmont Natural Gas [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	111	141
Net amounts recognized on the Condensed Consolidated Balance Sheet	111	141
Piedmont Natural Gas [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	9	8
Net amounts recognized on the Condensed Consolidated Balance Sheet	9	8
Piedmont Natural Gas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	102	133
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 102	$ 133