VARIABLE INTEREST ENTITIES - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) subsidiary agreement	Feb. 02, 2023	Dec. 31, 2022 USD ($)	Jun. 30, 2013 USD ($)
Business Acquisition [Line Items]
Assets	$ 48,767		$ 46,108
TOTAL LIABILITIES	$ 37,851		35,465
Number of subsidiaries that issued environmental control bonds | subsidiary	2
Environmental control bonds outstanding	$ 218		247
Restricted cash	$ 42		46
Power Purchase Agreements
Business Acquisition [Line Items]
Number of long term power purchase agreements maintained by parent company with non utility generation entities | agreement	4
Power Purchase Agreements | Global Holding And PATH WV
Business Acquisition [Line Items]
Equity method investment, ownership percentage	0.00%
FET
Business Acquisition [Line Items]
Noncontrolling interest ownership percentage	19.90%	49.90%
FE | FET
Business Acquisition [Line Items]
Ownership percentage by parent	80.10%	50.10%
Minority interest ownership percentage sold percentage		0.30
MP, PE and the Ohio Companies
Business Acquisition [Line Items]
Restricted cash	$ 40		41
Phase In Recovery Bonds
Business Acquisition [Line Items]
Long-term debt and other long-term obligations	191		206
Phase In Recovery Bonds | Ohio Funding Companies
Business Acquisition [Line Items]
Face amount of loan				$ 445
Variable Interest Entity, Primary Beneficiary
Business Acquisition [Line Items]
Assets	10,984		10,063
TOTAL LIABILITIES	7,426		7,120
Variable Interest Entity, Primary Beneficiary | FE
Business Acquisition [Line Items]
Assets	11,024		10,104
TOTAL LIABILITIES	$ 7,835		$ 7,573