Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	$ 191	$ 252
Net amounts recognized on the Condensed Consolidated Balance Sheet	191	252
Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	60	52
Gross amounts offset	(4)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	56	41
Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	131	200
Gross amounts offset	(2)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	129	198
Duke Energy Carolinas [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	25	16
Net amounts recognized on the Condensed Consolidated Balance Sheet	25	16
Duke Energy Carolinas [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	24
Gross amounts offset	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	23
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	1	16
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet		15
Progress Energy [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	22	25
Net amounts recognized on the Condensed Consolidated Balance Sheet	22	25
Progress Energy [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	11	12
Gross amounts offset	(3)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	1
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	11	13
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	10	12
Duke Energy Progress [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	7	7
Net amounts recognized on the Condensed Consolidated Balance Sheet	7	7
Duke Energy Progress [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	2
Gross amounts offset	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	1
Duke Energy Progress [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	5	7
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	4	6
Duke Energy Florida [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	9	12
Net amounts recognized on the Condensed Consolidated Balance Sheet	9	12
Duke Energy Florida [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	9	12
Gross amounts offset	(2)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	7	1
Duke Energy Ohio [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	5	6
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	6
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	4	5
Net amounts recognized on the Condensed Consolidated Balance Sheet	4	5
Duke Energy Indiana [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		2
Net amounts recognized on the Condensed Consolidated Balance Sheet		2
Duke Energy Indiana [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized		2
Net amounts recognized on the Condensed Consolidated Balance Sheet		2
Piedmont Natural Gas [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	123	187
Net amounts recognized on the Condensed Consolidated Balance Sheet	123	187
Piedmont Natural Gas [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	18	35
Net amounts recognized on the Condensed Consolidated Balance Sheet	18	35
Piedmont Natural Gas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	105	152
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 105	$ 152