Severance (Expenses) (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Restructuring Cost and Reserve [Line Items]
Severance expense		$ 187	$ 187	$ 15	$ 118
Duke Energy Carolinas [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		102	102	2	39
Progress Energy [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		69	69	2	40
Duke Energy Progress [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		52	52	1	23
Duke Energy Florida [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		17	17	1	17
Duke Energy Ohio [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		6	6		3
Duke Energy Indiana [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense		7	7	1	$ 7
Piedmont Natural Gas [Member]
Restructuring Cost and Reserve [Line Items]
Severance expense	$ 3	$ 2	$ 2	$ 9		$ 19