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Regulatory Matters (Duke Energy Carolinas Narrative) (Details) $ in Millions |  |  |  |  |  |  |  |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 30, 2019 USD ($) | May 21, 2019 USD ($) | Nov. 08, 2018 USD ($) | Aug. 09, 2018 plant | Jul. 05, 2018 plant | Jun. 22, 2018 USD ($) | Feb. 15, 2018 USD ($) | Aug. 25, 2017 USD ($) | May 31, 2018 USD ($) plant MW | Feb. 28, 2018 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Aug. 16, 2019 USD ($)
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Operation, maintenance and other |  |  |  |  |  |  |  |  |  |  | $ 6,066 | $ 6,463 | $ 5,944 |
Regulatory assets |  |  |  |  |  |  |  |  |  |  | 15,018 | 15,622 |  |
AROs – coal ash |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  |  |  |  |  |  | 4,084 | 4,255 |  |
Duke Energy Carolinas |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Operation, maintenance and other |  |  |  |  |  |  |  |  |  |  | 1,868 | 2,130 | $ 2,021 |
Regulatory assets |  |  |  |  |  |  |  |  |  |  | 3,910 | 3,977 |  |
Duke Energy Carolinas | AROs – coal ash |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  |  |  |  |  |  | $ 1,696 | $ 1,725 |  |
Duke Energy Carolinas | NCUC | 2017 North Carolina Rate Case |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  |  |  |  |  | $ 647 |  |  |  |  |  |
Requested rate increase (decrease), percent |  |  |  |  |  |  |  | 13.60% |  |  |  |  |  |
Requested return on equity, percentage |  |  |  |  |  |  |  |  |  | 9.90% |  |  |  |
Requested capital structure, percentage |  |  |  |  |  |  |  |  |  | 52.00% |  |  |  |
Requested debt structure, percentage |  |  |  |  |  |  |  |  |  | 48.00% |  |  |  |
Operation, maintenance and other |  |  |  |  |  |  |  |  |  | $ 4 |  |  |  |
Impairment charges and Operation |  |  |  |  |  | $ 150 |  |  |  |  |  |  |  |
Management penalty assessed |  |  |  |  |  | 70 |  |  |  |  |  |  |  |
Reduction of annual recovery of deferred coal ash costs |  |  |  |  |  | $ 14 |  |  |  |  |  |  |  |
Duke Energy Carolinas | NCUC | 2019 North Carolina Rate Case |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) | $ 291 |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percent | 6.00% |  |  |  |  |  |  |  |  |  |  |  |  |
Requested gross rate case revenue increase | $ 445 |  |  |  |  |  |  |  |  |  |  |  |  |
Requested EDIT rider decrease | $ 154 |  |  |  |  |  |  |  |  |  |  |  |  |
Duke Energy Carolinas | NCUC | 2018 Sale of Hydro Plants |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 32
Number of Hydroelectric Plants | plant |  |  |  |  |  |  |  |  | 5 |  |  |  |  |
Plant capacity | MW |  |  |  |  |  |  |  |  | 18.7 |  |  |  |  |
Total estimated loss on the sale |  |  |  |  |  |  |  |  | $ 40 |  |  |  |  |
Duke Energy Carolinas | PSCSC | 2018 South Carolina Rate Case |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  | $ 168 |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), percent |  |  | 10.00% |  |  |  |  |  |  |  |  |  |  |
Tax benefit from change in enacted tax rates |  | $ (66) | $ 66 |  |  |  |  |  |  |  |  |  |  |
Measurement period adjustments |  | $ 45 | $ 46 |  |  |  |  |  |  |  |  |  |  |
Approved return on equity, percentage |  | 9.50% |  |  |  |  |  |  |  |  |  |  |  |
Approved capital structure, percentage |  | 53.00% |  |  |  |  |  |  |  |  |  |  |  |
Approved debt structure, percentage |  | 47.00% |  |  |  |  |  |  |  |  |  |  |  |
Duke Energy Carolinas | PSCSC | 2018 South Carolina Rate Case | AROs – coal ash |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Recovery period |  |  | 5 years |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  | $ 96 | $ 242 |  |  |  |  |  |  |  |  |  |  |
Denied recovery costs |  | $ 115 |  |  |  |  |  |  |  |  |  |  |  |
Duke Energy Carolinas | PSCSC | 2018 South Carolina Rate Case | Deferred project costs |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Recovery period |  | 12 years |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  | $ 125 |  |  |  |  |  |  |  |  |  |  |  |
Duke Energy Carolinas | PSCSC | 2018 South Carolina Rate Case | State | North Carolina DOR |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Tax benefit from reduction in state taxes |  |  | $ 17 |  |  |  |  |  |  |  |  |  |  |
Approved decrease through EDIT Rider |  | $ 17 |  |  |  |  |  |  |  |  |  |  |  |
Duke Energy Carolinas | FERC | FERC Formula Rate Matter |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Customer refunds |  |  |  |  |  |  | $ 25 |  |  |  |  |  |  |
Duke Energy Carolinas | FERC | 2018 Sale of Hydro Plants |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Hydroelectric Plants | plant |  |  |  |  |  |  |  |  | 4 |  |  |  |  |
Northbrook | Duke Energy Carolinas | NCUC | 2018 Sale of Hydro Plants |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Hydroelectric Plants | plant |  |  |  |  | 5 |  |  |  |  |  |  |  |  |
Northbrook | Duke Energy Carolinas | NCUC | 2018 Sale of Hydro Plants, CPCNs |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Hydroelectric Plants | plant |  |  |  |  | 4 |  |  |  |  |  |  |  |  |
Northbrook | Duke Energy Carolinas | FERC | 2018 Sale of Hydro Plants |  |  |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of Hydroelectric Plants | plant |  |  |  | 4 |  |  |  |  |  |  |  |  |  |

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