Employee Benefit Plans (Contributions to Defined Benefit Pension Plans) (Details) - Qualified Pension Plans [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 155	$ 302
Anticipated contribution	160
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	43	91
Anticipated contribution	45
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	43	83
Anticipated contribution	45
Duke Energy Progress [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	24	42
Anticipated contribution	25
Duke Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	20	40
Anticipated contribution	20
Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	5	8
Anticipated contribution	4
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	9	$ 19
Anticipated contribution	$ 9