COMMITMENTS, GUARANTEES AND CONTINGENCIES - Schedule of Potential Amount of Future Payments (Details) $ in Millions	Jun. 30, 2026 USD ($)
Guarantor Obligations [Line Items]
Guarantor obligations	$ 1,051
JCP&L
Guarantor Obligations [Line Items]
Guarantor obligations	50
FE’s Guarantees on Behalf of its Consolidated Subsidiaries
Guarantor Obligations [Line Items]
Guarantor obligations	591
FE’s Guarantees on Other Assurances
Guarantor Obligations [Line Items]
Guarantor obligations	460
Deferred compensation arrangements \| FE’s Guarantees on Behalf of its Consolidated Subsidiaries
Guarantor Obligations [Line Items]
Guarantor obligations	394
Deferred compensation arrangements \| FE’s Guarantees on Other Assurances
Guarantor Obligations [Line Items]
Guarantor obligations	90
Vehicle leases \| FE’s Guarantees on Behalf of its Consolidated Subsidiaries
Guarantor Obligations [Line Items]
Guarantor obligations	75
Transfer of McElroy’s Run CCR impoundment facility \| FE’s Guarantees on Behalf of its Consolidated Subsidiaries
Guarantor Obligations [Line Items]
Guarantor obligations	107
Other \| FE’s Guarantees on Behalf of its Consolidated Subsidiaries
Guarantor Obligations [Line Items]
Guarantor obligations	15
Surety bonds \| FE’s Guarantees on Other Assurances
Guarantor Obligations [Line Items]
Guarantor obligations	160
Surety bonds \| FE’s Guarantees on Other Assurances \| JCP&L
Guarantor Obligations [Line Items]
Guarantor obligations	20
LOCs \| FE’s Guarantees on Other Assurances
Guarantor Obligations [Line Items]
Guarantor obligations	210
LOCs \| FE’s Guarantees on Other Assurances \| JCP&L
Guarantor Obligations [Line Items]
Guarantor obligations	$ 30