Employee Benefit Plans (Employee Savings Plans)(Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Savings Plans [Abstract]
Matching contribution percentage	100.00%
Eligible pay percentage	6.00%
Additional contribution percentage for employees not participating in defined pension plans	4.00%
Pretax employer matching contributions	$ 159	$ 143	$ 134
Duke Energy Carolinas [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	54	47	45
Progress Energy [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	48	43	45
Duke Energy Progress [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	34	30	25
Duke Energy Florida [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	13	14	14
Duke Energy Ohio [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	3	3	3
Duke Energy Indiana [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	$ 7	$ 7	$ 7