ORGANIZATION AND BASIS OF PRESENTATION - Narrative (Details) customer in Millions, $ in Millions				3 Months Ended			9 Months Ended
	Jul. 17, 2024 USD ($)	Mar. 25, 2024 USD ($) promissoryNote	May 31, 2022 USD ($)	Sep. 30, 2024 USD ($) mi² transmissionCenter	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) mi² customer transmissionCenter	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)	Feb. 02, 2023 USD ($)
Regulatory Asset [Line Items]
Number of customers | customer							6.0
Number of regional transmission centers | transmissionCenter				2			2
FET Equity Interest Sale (Note 1)					$ 2,673
Capitalized cost of equity				$ 16		$ 12	$ 42	$ 31
Capitalized interest				19		14	52	38
Equity method investment earnings (Note 1)				21		43	64	134
Impairment of long-lived assets to be disposed of				62
Revision of Prior Period, Adjustment
Regulatory Asset [Line Items]
Deferred tax assets, valuation allowance				21			21
Operating Segments
Regulatory Asset [Line Items]
Equity method investment earnings (Note 1)				0		0	0	0
NCI
Regulatory Asset [Line Items]
FET Equity Interest Sale (Note 1)					731
OPIC
Regulatory Asset [Line Items]
FET Equity Interest Sale (Note 1)					$ 1,942
Other Sundry Investments
Regulatory Asset [Line Items]
Equity method investments				109			109		$ 104
Global Holding
Regulatory Asset [Line Items]
Equity method investments				69			69		66
FE | FET
Regulatory Asset [Line Items]
Equity method investment, ownership percentage										50.10%
Variable Interest Entity, Not Primary Beneficiary | Path Wv
Regulatory Asset [Line Items]
Equity method investments				$ 17			$ 17		$ 17
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%
FET
Regulatory Asset [Line Items]
Noncontrolling interest, ownership percentage by noncontrolling owners				49.90%			49.90%
North American Transmission Company II LLC | FET
Regulatory Asset [Line Items]
Sale of ownership interest by parent										30.00%
Number of promissory notes | promissoryNote		2
Noncontrolling interest, ownership percentage by noncontrolling owners										49.90%
Regulated Transmission
Regulatory Asset [Line Items]
Service area | mi²				24,000			24,000
Regulated Transmission | Operating Segments
Regulatory Asset [Line Items]
Equity method investment earnings (Note 1)				$ 0		0	$ 0	0
Distribution Segment
Regulatory Asset [Line Items]
Number of customers | customer							4.2
Impairment of long-lived assets to be disposed of				31
Distribution Segment | Operating Segments
Regulatory Asset [Line Items]
Equity method investment earnings (Note 1)				0		0	$ 0	0
Integrated
Regulatory Asset [Line Items]
Number of customers | customer							2.0
Impairment of long-lived assets to be disposed of				17
Integrated | Operating Segments
Regulatory Asset [Line Items]
Equity method investment earnings (Note 1)				0		0	$ 0	0
Stand-Alone Transmission Segment
Regulatory Asset [Line Items]
Impairment of long-lived assets to be disposed of				11
Corporate Non Segment
Regulatory Asset [Line Items]
Impairment of long-lived assets to be disposed of				$ 3
FE PA
Regulatory Asset [Line Items]
Number of customers | customer							4.5
FET
Regulatory Asset [Line Items]
Net of transaction costs			$ 30
Net of taxes			$ 797
FET | North American Transmission Company II LLC
Regulatory Asset [Line Items]
Sale of ownership interest by parent		49.90%	19.90%
Consideration										$ 3,500
Brookfield | North American Transmission Company II LLC
Regulatory Asset [Line Items]
Interest income, operating							$ 24
Brookfield | North American Transmission Company II LLC | FET
Regulatory Asset [Line Items]
Business combination, consideration transferred, liabilities incurred	$ 1,200	$ 1,200
Cash paid in acquisition							$ 2,300
Brookfield | North American Transmission Company II LLC | FET | Promissory Note, $750 Million at 5.575% Due September 2025
Regulatory Asset [Line Items]
Face amount of debt		$ 750
Issuance interest rate		5.75%
Brookfield | North American Transmission Company II LLC | FET | Promissory Note, $450 Million at 7.75% Due September 2025
Regulatory Asset [Line Items]
Face amount of debt		$ 450
Issuance interest rate		7.75%
FEV | Global Holding
Regulatory Asset [Line Items]
Investment ownership percentage				33.30%			33.30%
FEV | Variable Interest Entity, Not Primary Beneficiary | Global Holding
Regulatory Asset [Line Items]
Proceeds from dividends received							$ 60	135
FEV | Corporate and Other | Global Holding | Other Nonoperating Income (Expense)
Regulatory Asset [Line Items]
Equity method investment earnings (Note 1)				$ 21		$ 43	$ 63	$ 132