Employee Benefit Plans (Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2015 USD ($)
Qualified Pension Plans [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	$ 628
2017	639
2018	640
2019	643
2020	641
2021-2025	3,053
Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	189
2017	199
2018	203
2019	202
2020	201
2021-2025	906
Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	164
2017	167
2018	169
2019	171
2020	174
2021-2025	869
Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	91
2017	92
2018	92
2019	91
2020	92
2021-2025	438
Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	71
2017	73
2018	75
2019	77
2020	80
2021-2025	420
Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	35
2017	35
2018	34
2019	34
2020	35
2021-2025	171
Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	48
2017	47
2018	47
2019	47
2020	47
2021-2025	230
Non-Qualified Pension Plans [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	28
2017	29
2018	25
2019	26
2020	25
2021-2025	126
Non-Qualified Pension Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	2
2017	2
2018	2
2019	2
2020	2
2021-2025	9
Non-Qualified Pension Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	8
2017	8
2018	8
2019	8
2020	8
2021-2025	38
Non-Qualified Pension Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	3
2017	3
2018	3
2019	3
2020	3
2021-2025	12
Non-Qualified Pension Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	3
2017	3
2018	3
2019	3
2020	3
2021-2025	16
Non-Qualified Pension Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2021-2025	1
Non-Qualified Pension Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2020	1
2021-2025	2
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	76
2017	76
2018	74
2019	73
2020	71
2021-2025	312
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	16
2017	17
2018	18
2019	18
2020	18
2021-2025	80
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	31
2017	31
2018	30
2019	29
2020	29
2021-2025	129
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	16
2017	16
2018	16
2019	15
2020	15
2021-2025	68
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	15
2017	15
2018	14
2019	14
2020	13
2021-2025	60
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	4
2017	3
2018	3
2019	3
2020	3
2021-2025	14
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2016	10
2017	10
2018	9
2019	9
2020	8
2021-2025	$ 33