Employee Benefit Plans (Employee Savings Plans) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Employee Savings Plans [Abstract]
Employer contributions	$ 39	$ 37	$ 91	$ 86
Duke Energy Carolinas [Member]
Employee Savings Plans [Abstract]
Employer contributions	13	13	31	29
Progress Energy [Member]
Employee Savings Plans [Abstract]
Employer contributions	12	12	27	26
Duke Energy Progress [Member]
Employee Savings Plans [Abstract]
Employer contributions	8	8	19	19
Duke Energy Florida [Member]
Employee Savings Plans [Abstract]
Employer contributions	4	3	8	7
Duke Energy Ohio [Member]
Employee Savings Plans [Abstract]
Employer contributions	1	1	2	2
Duke Energy Indiana [Member]
Employee Savings Plans [Abstract]
Employer contributions	$ 2	$ 2	$ 4	$ 4