Derivatives and Hedging (Schedule of Offsetting Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	$ 227	$ 252
Net amounts recognized on the Condensed Consolidated Balance Sheet	227	252
Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	69	52
Gross amounts offset	(4)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	65	41
Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	158	200
Gross amounts offset	(2)	(2)
Net amounts recognized on the Condensed Consolidated Balance Sheet	156	198
Duke Energy Carolinas [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	26	16
Net amounts recognized on the Condensed Consolidated Balance Sheet	26	16
Duke Energy Carolinas [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	23
Gross amounts offset	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	22
Duke Energy Carolinas [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	3	16
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	15
Progress Energy [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	35	25
Net amounts recognized on the Condensed Consolidated Balance Sheet	35	25
Progress Energy [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	21	12
Gross amounts offset	(4)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	17	1
Progress Energy [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	14	13
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	13	12
Duke Energy Progress [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	8	7
Net amounts recognized on the Condensed Consolidated Balance Sheet	8	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	6	7
Gross amounts offset	(1)	(1)
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	6
Duke Energy Florida [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	20	12
Net amounts recognized on the Condensed Consolidated Balance Sheet	20	12
Duke Energy Florida [Member] | Other Current Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	19	12
Gross amounts offset	(3)	(11)
Net amounts recognized on the Condensed Consolidated Balance Sheet	16	1
Duke Energy Florida [Member] | Other Noncurrent Liabilities [Member]
Offsetting Derivative Liabilities [Abstract]
Gross amounts recognized	1
Gross amounts offset	(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	145	187
Net amounts recognized on the Condensed Consolidated Balance Sheet	145	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	127	152
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 127	$ 152