Employee Benefit Plans (Employee Savings Plans)(Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Employee Savings Plans [Abstract]
Pretax employer matching contributions	$ 43	$ 41
Matching contribution percentage	100.00%
Eligible pay percentage	6.00%
Additional savings plan account contribution percentage for employees not participating in defined pension plans	4.00%
Duke Energy Carolinas [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	14	14
Progress Energy [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	12	12
Duke Energy Progress [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	9	6
Duke Energy Florida [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	4	4
Duke Energy Ohio [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	1	1
Duke Energy Indiana [Member]
Employee Savings Plans [Abstract]
Pretax employer matching contributions	$ 2	$ 2