Employee Benefit Plans (Contributions to Defined Benefit Pension Plans) (Details) - Qualified Pension Plans [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 302	$ 250
Anticipated contribution	145
Duke Energy Carolinas [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	91
Anticipated contribution	43
Progress Energy [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	83	250
Anticipated contribution	43
Duke Energy Progress [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	42	63
Anticipated contribution	24
Duke Energy Florida [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	40	$ 133
Anticipated contribution	20
Duke Energy Ohio [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	8
Anticipated contribution	4
Duke Energy Indiana [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	19
Anticipated contribution	$ 9