VARIABLE INTEREST ENTITIES - Narrative (Details) $ in Millions	Sep. 30, 2024 USD ($) agreement subsidiary	Dec. 31, 2023 USD ($)	Feb. 02, 2023	Jun. 30, 2013 USD ($)
Variable Interest Entity [Line Items]
Assets	$ 50,756	$ 48,767
Liabilities	$ 37,064	37,851
Number of subsidiaries that issued environmental control bonds | subsidiary	2
Long-term pollution control bond	$ 188	218
Restricted cash	$ 26	42
Number of long-term purchase power agreements | agreement	4
FET
Variable Interest Entity [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners	49.90%
Phase In Recovery Bonds
Variable Interest Entity [Line Items]
Long-term debt and other long-term obligations	$ 175	191
FE | FET
Variable Interest Entity [Line Items]
Minority interest ownership percentage sold percentage			0.30
Ownership percentage by parent	50.10%
Ohio Funding Companies | Phase In Recovery Bonds
Variable Interest Entity [Line Items]
Face amount of debt				$ 445
MP, PE and the Ohio Companies
Variable Interest Entity [Line Items]
Restricted cash	$ 24	40
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	11,624	10,984
Liabilities	8,609	7,426
Variable Interest Entity, Primary Beneficiary | FE
Variable Interest Entity [Line Items]
Assets	11,600	11,000
Liabilities	$ 9,000	$ 7,800