Employee Benefit Plans (Plan Contributions) (Details) - Qualified Pension Plan [Member] - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Contributions by Employer	$ 141,000,000	$ 0
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by Employer	46,000,000
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by Employer	45,000,000
Duke Energy Progress [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by Employer	25,000,000
Duke Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by Employer	20,000,000
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Contributions by Employer	$ 8,000,000