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CAPITALIZATION - Narrative (Details) $ / shares in Units, $ in Millions |  |  |  |  | 1 Months Ended | 2 Months Ended | 3 Months Ended | 12 Months Ended |  |
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Dec. 01, 2023 $ / shares | May 04, 2023 USD ($) tradingDay | May 01, 2023 | Nov. 06, 2021 USD ($) $ / shares shares | Sep. 30, 2023 $ / shares | Dec. 31, 2021 USD ($) | Dec. 31, 2023 USD ($) $ / shares shares | Jun. 30, 2023 $ / shares | Mar. 31, 2023 $ / shares | Dec. 31, 2022 USD ($) $ / shares shares | Sep. 30, 2022 $ / shares | Jun. 30, 2022 $ / shares | Mar. 31, 2022 $ / shares | Dec. 31, 2024 USD ($) | Dec. 31, 2023 USD ($) subsidiary $ / shares shares | Dec. 31, 2022 USD ($) $ / shares shares | Dec. 31, 2021 $ / shares shares | Apr. 30, 2023 | Jun. 30, 2013 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Accumulated deficit |  |  |  |  |  |  | $ (97) |  |  | $ (1,199) |  |  |  |  | $ (97) | $ (1,199) |  |  |
Dividends declared (in dollars per share) | $ / shares |  |  |  |  | $ 0.02 |  | $ 0.41 | $ 0.39 | $ 0.39 | $ 0.39 | $ 0.39 | $ 0.39 | $ 0.39 |  | $ 1.60 | $ 1.56 | $ 1.56 |  |
Dividends paid (in dollars per share) | $ / shares | $ 0.41 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase in dividend percentage | 0.05 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
FERC-defined equity to total capitalization ratio |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 35.00% |  |  |  |
Common Stock, Par or Stated Value Per Share | $ / shares |  |  |  |  |  |  | $ 0.10 |  |  | $ 0.10 |  |  |  |  | $ 0.10 | $ 0.10 |  |  |
Preference shares outstanding (in shares) | shares |  |  |  |  |  |  | 0 |  |  | 0 |  |  |  |  | 0 | 0 |  |  |
Preferred shares, outstanding (in shares) | shares |  |  |  |  |  |  | 0 |  |  | 0 |  |  |  |  | 0 | 0 |  |  |
Number of subsidiaries that issued environmental control bonds | subsidiary |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2 |  |  |  |
Environmental control bonds outstanding |  |  |  |  |  |  | $ 218 |  |  | $ 247 |  |  |  |  | $ 218 | $ 247 |  |  |
Principal default amount specified in debt covenants |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 100 |  |  |  |
Common Stock Purchase Agreement |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares issued in transaction | shares |  |  |  | 25,588,535 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common Stock, Par or Stated Value Per Share | $ / shares |  |  |  | $ 0.10 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of stock, price per share (in dollars per share) | $ / shares |  |  |  | $ 39.08 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Investment amount |  |  |  | $ 1,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Transaction costs |  |  |  |  |  | $ 26 |  |  |  |  |  |  |  |  |  |  |  |  |
Registered Shareholders, Directors and Employees of Subsidiaries |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Consolidated tax benefit allocation (in shares) | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 2,000,000 | 2,000,000 | 1,000,000 |  |
AGC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
FERC-defined equity to total capitalization ratio |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 45.00% |  |  |  |
FET | Brookfield II | Forecast |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Discontinued Operation, Tax Effect of Gain (Loss) from Disposal of Discontinued Operation |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 7,000 |  |  |  |  |
4.00%, $1,500 Million Notes Maturity 2026 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of debt |  | $ 1,480 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
4.00%, $1,500 Million Notes Maturity 2026 | FE | Promissory Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of loan |  | $ 1,500 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, convertible, threshold trading days | tradingDay |  | 20 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, convertible, threshold consecutive trading days | tradingDay |  | 30 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, convertible, threshold percentage of stock price trigger |  | 130.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, convertible, business days | tradingDay |  | 5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Threshold trading days measurement period | tradingDay |  | 10 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, measurement period percentage |  | 98.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, conversation price (in dollars per share) | $ / shares |  |  |  |  |  |  | $ 46.81 |  |  |  |  |  |  |  | $ 46.81 |  |  |  |
Debt instrument convertible premium |  |  | 0.20 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Repurchase price, percentage |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Phase In Recovery Bonds |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Long-term debt and other long-term obligations |  |  |  |  |  |  | $ 191 |  |  | $ 206 |  |  |  |  | $ 191 | $ 206 |  |  |
Phase In Recovery Bonds | Ohio Funding Companies |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Face amount of loan |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 445
2026 Convertible Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, convertible, conversion ratio |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0.021362 |  |  |  |
2026 Convertible Notes | Unsecured Debt |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Interest Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4.00% |

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