Severance (Expenses) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Severance expense	$ (85)	$ 16	$ 187
Unamortized deferred severance	(86)
Severance charges adjustments	(6)
Duke Energy Carolinas
Restructuring Cost and Reserve [Line Items]
Severance expense	(58)	8	102
Unamortized deferred severance	(57)
Severance charges adjustments	(2)
Progress Energy
Restructuring Cost and Reserve [Line Items]
Severance expense	(28)	6	69
Unamortized deferred severance	(29)
Severance charges adjustments	(3)
Duke Energy Progress
Restructuring Cost and Reserve [Line Items]
Severance expense	(31)	3	52
Unamortized deferred severance	(29)
Severance charges adjustments	(2)
Duke Energy Florida
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 3	3	17
Duke Energy Ohio
Restructuring Cost and Reserve [Line Items]
Severance expense			6
Duke Energy Indiana
Restructuring Cost and Reserve [Line Items]
Severance expense		1	7
Piedmont
Restructuring Cost and Reserve [Line Items]
Severance expense		$ 1	$ 2