Commitments and Contingencies (Schedule of Environmental Loss Contingencies) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Environmental Matters Details [Line Items]
Reserves for Environmental Remediation	$ 66	$ 58
Environmental exit costs, reasonably possible additional loss	56
Duke Energy Carolinas
Environmental Matters Details [Line Items]
Reserves for Environmental Remediation	16	11
Environmental exit costs, reasonably possible additional loss	12
Progress Energy
Environmental Matters Details [Line Items]
Reserves for Environmental Remediation	15	16
Duke Energy Progress
Environmental Matters Details [Line Items]
Reserves for Environmental Remediation	5	4
Duke Energy Florida
Environmental Matters Details [Line Items]
Reserves for Environmental Remediation	8	9
Duke Energy Ohio
Environmental Matters Details [Line Items]
Reserves for Environmental Remediation	22	19
Environmental exit costs, reasonably possible additional loss	38
Duke Energy Indiana
Environmental Matters Details [Line Items]
Reserves for Environmental Remediation	5	4
Piedmont Natural Gas
Environmental Matters Details [Line Items]
Reserves for Environmental Remediation	$ 8	$ 8