Employee Benefit Plans (Contributions to Defined Benefit Pension Plans) (Details) - Pension Plan $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 77
Duke Energy Carolinas
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	7
Progress Energy
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	57
Duke Energy Progress
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	4
Duke Energy Florida
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	53
Duke Energy Ohio
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	2
Duke Energy Indiana
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	2
Piedmont
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 1