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Regulatory Matters (Duke Energy Carolinas Narrative) (Details) - USD ($) $ in Millions |  |  |  |  |  |  |  |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 26, 2020 | Jul. 31, 2020 | Sep. 30, 2019 | May 21, 2019 | Nov. 08, 2018 | Jun. 22, 2018 | Feb. 28, 2018 | Aug. 25, 2017 | Mar. 31, 2018 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | $ 984 | $ (8) | $ 402
Regulatory assets |  |  |  |  |  |  |  |  |  | 14,062 | 15,018 |
AROs – coal ash |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  |  |  |  |  | 3,408 | 4,084 |
Duke Energy Carolinas |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Impairment charges |  |  |  |  |  |  |  |  |  | 476 | 17 | $ 192
Regulatory assets |  |  |  |  |  |  |  |  |  | 3,469 | 3,910 |
Duke Energy Carolinas | AROs – coal ash |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  |  |  |  |  |  |  | $ 1,414 | $ 1,696 |
Duke Energy Carolinas | NCUC | 2017 North Carolina Rate Case |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  |  |  |  |  | $ 647 |  |  |  |
Requested return on equity, percentage |  |  |  |  |  |  | 9.90% |  |  |  |  |
Requested capital structure, percentage |  |  |  |  |  |  | 52.00% |  |  |  |  |
Requested debt structure, percentage |  |  |  |  |  |  | 48.00% |  |  |  |  |
Impairment charges |  |  |  |  |  | $ 150 |  |  | $ 14 |  |  |
Management penalty assessed |  |  |  |  |  | 70 |  |  |  |  |  |
Recovery costs reduction |  |  |  |  |  | $ 14 |  |  |  |  |  |
Recovery period |  |  |  |  |  | 5 years |  |  |  |  |  |
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 | North Carolina Utilities Commission |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), amended, amount | $ 287 |  |  |  |  |  |  |  |  |  |  |
Duke Energy Carolinas | North Carolina Utilities Commission | 2019 North Carolina Rate Case, Additional Agreement and Stipulation of Partial Settlement |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Requested return on equity, percentage |  | 9.60% |  |  |  |  |  |  |  |  |  |
Requested capital structure, percentage |  | 52.00% |  |  |  |  |  |  |  |  |  |
Requested debt structure, percentage |  | 48.00% |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), amended, amount |  | $ 800 |  |  |  |  |  |  |  |  |  |
Duke Energy Carolinas | North Carolina Utilities Commission | 2019 North Carolina Rate Case, Additional Agreement and Stipulation of Partial Settlement, Estimated Annual Revenue Requirement |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease), amended, amount |  | $ 45 |  |  |  |  |  |  |  |  |  |
Duke Energy Carolinas | PSCSC | 2018 South Carolina Rate Case |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Requested rate increase (decrease) |  |  |  |  | $ 168 |  |  |  |  |  |  |
Approved return on equity, percentage |  |  |  | 9.50% |  |  |  |  |  |  |  |
Approved capital structure, percentage |  |  |  | 53.00% |  |  |  |  |  |  |  |
Approved debt structure, percentage |  |  |  | 47.00% |  |  |  |  |  |  |  |
Tax benefit from change in enacted tax rates |  |  |  | $ (66) |  |  |  |  |  |  |  |
Measurement period adjustment |  |  |  | $ (45) |  |  |  |  |  |  |  |
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 | AROs – coal ash |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Regulatory assets |  |  |  | 96 |  |  |  |  |  |  |  |
Denied recovery costs |  |  |  | 115 |  |  |  |  |  |  |  |
Duke Energy Carolinas | PSCSC | 2018 South Carolina Rate Case | State | North Carolina DOR |  |  |  |  |  |  |  |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Approved decrease through EDIT Rider |  |  |  | $ 17 |  |  |  |  |  |  |  |

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