Severance (Expenses) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 187	$ 16	$ 187	$ 15
Duke Energy Carolinas
Restructuring Cost and Reserve [Line Items]
Severance expense	102	8	102	2
Progress Energy
Restructuring Cost and Reserve [Line Items]
Severance expense	69	6	69	2
Duke Energy Progress
Restructuring Cost and Reserve [Line Items]
Severance expense	52	3	52	1
Duke Energy Florida
Restructuring Cost and Reserve [Line Items]
Severance expense	17	3	17	1
Duke Energy Ohio
Restructuring Cost and Reserve [Line Items]
Severance expense	6		6
Duke Energy Indiana
Restructuring Cost and Reserve [Line Items]
Severance expense	7	1	7	1
Piedmont
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 2	$ 1	$ 2	$ 9