Commitments and Contingencies (Purchased Power) (Details) - Purchased Power Contracts $ in Millions	12 Months Ended
Dec. 31, 2019 USD ($)
Duke Energy Progress
Unconditional Purchase Obligations [Abstract]
2020	$ 46
2021	66
2022	63
2023	55
2024	56
Thereafter	123
Total	$ 409
Duke Energy Progress \| Maximum
Unconditional Purchase Obligations [Abstract]
Net plant output percent	100.00%
Duke Energy Florida
Unconditional Purchase Obligations [Abstract]
2020	$ 374
2021	356
2022	354
2023	374
2024	262
Thereafter	91
Total	$ 1,811
Duke Energy Florida \| Minimum
Unconditional Purchase Obligations [Abstract]
Net plant output percent	81.00%
Duke Energy Florida \| Maximum
Unconditional Purchase Obligations [Abstract]
Net plant output percent	100.00%
Duke Energy Ohio
Unconditional Purchase Obligations [Abstract]
2020	$ 132
2021	107
2022	32
Total	$ 271
Duke Energy Ohio \| Minimum
Unconditional Purchase Obligations [Abstract]
Net plant output percent	1.00%
Duke Energy Ohio \| Maximum
Unconditional Purchase Obligations [Abstract]
Net plant output percent	9.00%

Share of plant output being purchased under a long-term contract to purchase electricity from a production plant constructed and financed by a public utility district, cooperative, or other organization.

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Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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