Derivatives and Hedging (Schedule of Offsetting Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	$ 31	$ 57
Net amounts recognized on the Condensed Consolidated Balance Sheet	31	57
Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	31	38
Gross amounts offset	(5)	(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet	26	35
Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		19
Gross amounts offset		(3)
Net amounts recognized on the Condensed Consolidated Balance Sheet		16
Duke Energy Carolinas [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		3
Net amounts recognized on the Condensed Consolidated Balance Sheet		3
Duke Energy Carolinas [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		2
Gross amounts offset		(2)
Duke Energy Carolinas [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		1
Gross amounts offset		(1)
Progress Energy [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	4
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	4
Progress Energy [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	2
Gross amounts offset	(5)	(2)
Progress Energy [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		2
Gross amounts offset		(2)
Duke Energy Progress [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		4
Net amounts recognized on the Condensed Consolidated Balance Sheet		4
Duke Energy Progress [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		2
Gross amounts offset		(2)
Duke Energy Progress [Member] | Noncurrent Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized		2
Gross amounts offset		(2)
Duke Energy Florida [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5
Net amounts recognized on the Condensed Consolidated Balance Sheet	5
Duke Energy Florida [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5
Gross amounts offset	(5)
Duke Energy Ohio [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	6
Duke Energy Ohio [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	5	6
Net amounts recognized on the Condensed Consolidated Balance Sheet	5	6
Duke Energy Indiana [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	16	23
Net amounts recognized on the Condensed Consolidated Balance Sheet	16	23
Duke Energy Indiana [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	16	23
Net amounts recognized on the Condensed Consolidated Balance Sheet	16	23
Piedmont Natural Gas [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	2	3
Piedmont Natural Gas [Member] | Current Assets, Other [Member]
Offsetting Derivative Assets [Abstract]
Gross amounts recognized	2	3
Net amounts recognized on the Condensed Consolidated Balance Sheet	$ 2	$ 3