Employee Benefit Plans (Expected Benefit Payments) (Details) $ in Millions	Dec. 31, 2019 USD ($)
Pension Plan | Qualified Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	$ 643
2021	653
2022	649
2023	649
2024	638
2025-2029	2,851
Pension Plan | Duke Energy Carolinas | Qualified Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	167
2021	171
2022	177
2023	174
2024	168
2025-2029	714
Pension Plan | Progress Energy | Qualified Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	169
2021	178
2022	176
2023	182
2024	184
2025-2029	871
Pension Plan | Duke Energy Progress | Qualified Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	89
2021	95
2022	92
2023	95
2024	96
2025-2029	419
Pension Plan | Duke Energy Florida | Qualified Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	79
2021	82
2022	84
2023	86
2024	87
2025-2029	448
Pension Plan | Duke Energy Ohio | Qualified Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	37
2021	37
2022	37
2023	36
2024	35
2025-2029	156
Pension Plan | Duke Energy Indiana | Qualified Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	50
2021	50
2022	49
2023	48
2024	48
2025-2029	220
Pension Plan | Piedmont | Qualified Plan
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	28
2021	24
2022	22
2023	21
2024	20
2025-2029	87
Other Post-Retirement Benefit Plans
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	76
2021	70
2022	66
2023	63
2024	59
2025-2029	246
Other Post-Retirement Benefit Plans | Duke Energy Carolinas
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	18
2021	17
2022	16
2023	15
2024	15
2025-2029	60
Other Post-Retirement Benefit Plans | Progress Energy
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	29
2021	28
2022	27
2023	25
2024	24
2025-2029	101
Other Post-Retirement Benefit Plans | Duke Energy Progress
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	16
2021	15
2022	14
2023	14
2024	13
2025-2029	55
Other Post-Retirement Benefit Plans | Duke Energy Florida
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	13
2021	13
2022	12
2023	12
2024	11
2025-2029	46
Other Post-Retirement Benefit Plans | Duke Energy Ohio
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	4
2021	3
2022	3
2023	3
2024	3
2025-2029	11
Other Post-Retirement Benefit Plans | Duke Energy Indiana
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	8
2021	7
2022	7
2023	6
2024	6
2025-2029	23
Other Post-Retirement Benefit Plans | Piedmont
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2020	2
2021	2
2022	2
2023	2
2024	2
2025-2029	$ 11