Employee Benefit Plans (Employee Savings Plans) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employee Savings Plans [Abstract]
Employer contributions	$ 39	$ 34	$ 130	$ 120
Duke Energy Carolinas [Member]
Employee Savings Plans [Abstract]
Employer contributions	13	11	44	40
Progress Energy [Member]
Employee Savings Plans [Abstract]
Employer contributions	12	10	39	36
Duke Energy Progress [Member]
Employee Savings Plans [Abstract]
Employer contributions	8	7	27	26
Duke Energy Florida [Member]
Employee Savings Plans [Abstract]
Employer contributions	3	3	11	10
Duke Energy Ohio [Member]
Employee Savings Plans [Abstract]
Employer contributions	1		3	2
Duke Energy Indiana [Member]
Employee Savings Plans [Abstract]
Employer contributions	$ 2	$ 1	$ 6	$ 5