Employee Benefit Plans (Narrative) (Details)	9 Months Ended
Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Matching contribution percentage	100.00%
Eligible pay percentage	6.00%
Additional savings plan account contribution percentage for employees not participating in defined pension plans	4.00%

Percentage of eligible pay per period contributed to an employee's 401(k) account in lieu of participation in Duke Energy's defined pension plans.

No definition available.

Name:	duk_DefinedContributionPlanAdditionalContributionPercentageForEmployeesNotParticipatingInDefinedPensionPlans
Namespace Prefix:	duk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration