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ORGANIZATION AND BASIS OF PRESENTATION - Narrative (Details) individual in Millions, customer in Millions, $ in Millions |  |  |  | 3 Months Ended | 9 Months Ended |  |  |
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Jul. 16, 2025 USD ($) | Mar. 24, 2025 employee | Feb. 26, 2025 USD ($) substation transmission_project mi kV | Sep. 30, 2025 USD ($) individual transmissionCenter mi MW | Mar. 31, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) customer individual transmissionCenter mi MW | Sep. 30, 2024 USD ($) | Jul. 31, 2025 | Feb. 21, 2025 | Dec. 31, 2024 USD ($)
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of customers | customer |  |  |  |  |  |  | 6.0 |  |  |  |
Number of regional transmission centers | transmissionCenter |  |  |  | 2 |  |  | 2 |  |  |  |
Net increase to income before income taxes |  |  |  | $ 610.0 |  | $ 560.0 | $ 1,556.0 | $ 1,125.0 |  |  |
Capitalized cost of equity |  |  |  | 30.0 |  | 16.0 | 76.0 | 42.0 |  |  |
Capitalized interest |  |  |  | 21.0 |  | 19.0 | 55.0 | 52.0 |  |  |
Equity method investment earnings, net (Note 1) |  |  |  | 0.0 |  | 21.0 | 0.0 | 64.0 |  |  |
Organizational Changes |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Expected number of employees reassigned | employee |  | 200 |  |  |  |  |  |  |  |  |
Percentage of employees reduced from workforce |  | 3.00% |  |  |  |  |  |  |  |  |
Restructuring charges |  |  |  |  | $ 26.0 |  |  |  |  |  |
Revision of Prior Period, Adjustment |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net increase to income before income taxes |  |  |  | 21.0 |  |  |  |  |  |  |
Other Sundry Investments |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investments |  |  |  | 38.0 |  |  | 38.0 |  |  |  | $ 84.0
Global Holding |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investments |  |  |  |  |  |  |  |  |  |  | 45.0
Valley Link |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investments |  |  |  | 0.0 |  |  | 0.0 |  |  |  | 0.0
Valley Link | PJM |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of transmission projects | transmission_project |  |  | 2 |  |  |  |  |  |  |  |
Valley Link | PJM | PJM 2024 RTEP Window 1 |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Transmission solutions to the reliability issues |  |  | $ 3,000.0 |  |  |  |  |  |  |  |
Valley Link | PJM | Putnam County, West Virginia to Frederick, Maryland |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Service area | mi |  |  | 260 |  |  |  |  |  |  |  |
Transmission line electrical potential (in kV) | kV |  |  | 765 |  |  |  |  |  |  |  |
Number of substations | substation |  |  | 2 |  |  |  |  |  |  |  |
Valley Link | PJM | Campbell County, Virginia and Fauquier County, Virginia |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Service area | mi |  |  | 155 |  |  |  |  |  |  |  |
Transmission line electrical potential (in kV) | kV |  |  | 765 |  |  |  |  |  |  |  |
Path Wv | Variable Interest Entity, Not Primary Beneficiary |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investments |  |  |  | $ 17.0 |  |  | $ 17.0 |  |  |  | 17.0
Variable interest entities percentage of high voltage transmission line project owned By variable interest entity one in joint venture party one |  |  |  | 100.00% |  |  | 100.00% |  |  |  |
Variable interest entities percentage of high voltage transmission line project owned by variable interest entity one in joint venture party two |  |  |  | 50.00% |  |  | 50.00% |  |  |  |
VEPCO and Transource Energy, LLC | Valley Link |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investments |  |  | $ 3,000.0 |  |  |  |  |  |  |  |
JERSEY CENTRAL POWER & LIGHT COMPANY |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of customers | customer |  |  |  |  |  |  | 1.2 |  |  |  |
Transmission services available area populations | individual |  |  |  | 2.8 |  |  | 2.8 |  |  |  |
Net increase to income before income taxes |  |  |  | $ 160.0 |  | 150.0 | $ 313.0 | 216.0 |  |  |
Capitalized cost of equity |  |  |  | 8.0 |  | 1.0 | 21.0 | 3.0 |  |  |
Capitalized interest |  |  |  | 4.0 |  | 5.0 | 10.0 | 16.0 |  |  |
JERSEY CENTRAL POWER & LIGHT COMPANY | Organizational Changes |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Restructuring charges |  |  |  |  | $ 5.0 |  |  |  |  |  |
JERSEY CENTRAL POWER & LIGHT COMPANY | Revision of Prior Period, Adjustment |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Net increase to income before income taxes |  |  |  | 4.0 |  |  |  |  |  |  |
JERSEY CENTRAL POWER & LIGHT COMPANY | Other Sundry Investments |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investments |  |  |  | $ 0.0 |  |  | $ 0.0 |  |  |  | $ 0.0
Brookfield | FET | North American Transmission Company II LLC |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investment, ownership percentage |  |  |  | 49.90% |  |  | 49.90% |  |  |  |
FET | Valley Link |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investment, ownership percentage |  |  |  |  |  |  |  |  |  | 34.00% |
FET | Valley Link | PJM | PJM 2024 RTEP Window 1 |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Transmission solutions to the reliability issues |  |  | $ 1,000.0 |  |  |  |  |  |  |  |
FEV | Global Holding |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investments |  |  |  | $ 47.5 |  |  | $ 47.5 |  |  |  |
Investment ownership percentage | 33.33% |  |  |  |  |  |  |  | 33.33% |  |
Ownership percentage sold | 0.3333 |  |  |  |  |  |  |  |  |  |
Proceeds from investments sold | $ 47.5 |  |  |  |  |  |  |  |  |  |
FEV | Global Holding | Variable Interest Entity, Not Primary Beneficiary |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Proceeds from dividends received |  |  |  |  |  |  |  | 60.0 |  |  |
Dominion HV | Valley Link |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investment, ownership percentage |  |  |  |  |  |  |  |  |  | 30.00% |
Transource | Valley Link |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investment, ownership percentage |  |  |  |  |  |  |  |  |  | 36.00% |
Regulated Transmission |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Service area | mi |  |  |  | 24,000 |  |  | 24,000 |  |  |  |
Integrated Segment |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Number of customers | customer |  |  |  |  |  |  | 2.0 |  |  |  |
Plant capacity (in MW's) | MW |  |  |  | 3,610 |  |  | 3,610 |  |  |  |
Corporate and Other | FEV | Global Holding | Other Nonoperating Income (Expense) |  |  |  |  |  |  |  |  |  |  |
Regulatory Asset [Line Items] |  |  |  |  |  |  |  |  |  |  |
Equity method investment earnings, net (Note 1) |  |  |  |  |  | $ 21.0 |  | $ 63.0 |  |  |

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