Employee Benefit Plans (Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2018 USD ($)
Pension Plan [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	$ 662
2020	651
2021	663
2022	662
2023	655
2024-2028	2,993
Pension Plan [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	22
2020	21
2021	23
2022	25
2023	25
2024-2028	125
Pension Plan [Member] | Duke Energy Carolinas [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	210
2020	177
2021	182
2022	189
2023	185
2024-2028	794
Pension Plan [Member] | Duke Energy Carolinas [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	2
2020	1
2021	1
2022	1
2023	3
2024-2028	10
Pension Plan [Member] | Progress Energy [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	179
2020	171
2021	177
2022	179
2023	181
2024-2028	902
Pension Plan [Member] | Progress Energy [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	8
2020	8
2021	8
2022	8
2023	7
2024-2028	37
Pension Plan [Member] | Duke Energy Progress [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	105
2020	90
2021	95
2022	94
2023	95
2024-2028	451
Pension Plan [Member] | Duke Energy Progress [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	3
2020	2
2021	2
2022	2
2023	2
2024-2028	11
Pension Plan [Member] | Duke Energy Florida [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	73
2020	80
2021	81
2022	84
2023	85
2024-2028	447
Pension Plan [Member] | Duke Energy Florida [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	3
2020	3
2021	3
2022	3
2023	3
2024-2028	15
Pension Plan [Member] | Duke Energy Ohio [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	33
2020	37
2021	37
2022	37
2023	35
2024-2028	158
Pension Plan [Member] | Duke Energy Ohio [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2024-2028	1
Pension Plan [Member] | Duke Energy Indiana [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	47
2020	51
2021	51
2022	49
2023	47
2024-2028	217
Pension Plan [Member] | Duke Energy Indiana [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2024-2028	1
Pension Plan [Member] | Piedmont Natural Gas [Member] | Qualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	20
2020	24
2021	23
2022	22
2023	22
2024-2028	96
Pension Plan [Member] | Piedmont Natural Gas [Member] | Nonqualified Plan [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2024-2028	2
Other Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	81
2020	75
2021	71
2022	68
2023	64
2024-2028	266
Other Post-Retirement Benefit Plans [Member] | Duke Energy Carolinas [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	19
2020	18
2021	18
2022	17
2023	16
2024-2028	64
Other Post-Retirement Benefit Plans [Member] | Progress Energy [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	30
2020	29
2021	28
2022	27
2023	26
2024-2028	109
Other Post-Retirement Benefit Plans [Member] | Duke Energy Progress [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	16
2020	15
2021	15
2022	14
2023	14
2024-2028	59
Other Post-Retirement Benefit Plans [Member] | Duke Energy Florida [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	14
2020	13
2021	13
2022	12
2023	12
2024-2028	50
Other Post-Retirement Benefit Plans [Member] | Duke Energy Ohio [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	3
2020	3
2021	3
2022	3
2023	3
2024-2028	11
Other Post-Retirement Benefit Plans [Member] | Duke Energy Indiana [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	9
2020	8
2021	7
2022	7
2023	6
2024-2028	26
Other Post-Retirement Benefit Plans [Member] | Piedmont Natural Gas [Member]
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2019	2
2020	2
2021	2
2022	3
2023	3
2024-2028	$ 12