Employee Benefit Plans - Summary of Contributions (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Contributions made	$ 77
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions made	7
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions made	57
Duke Energy Progress [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions made	4
Duke Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions made	53
Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions made	2
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions made	2
Piedmont Natural Gas [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions made	$ 1