REGULATORY MATTERS - Pennsylvania and West Virginia (Details) $ in Thousands														3 Months Ended	12 Months Ended
	Jan. 23, 2024 USD ($)	Nov. 30, 2023 USD ($)	Aug. 31, 2023 USD ($)	Aug. 30, 2023 USD ($)	Aug. 22, 2023 USD ($)	May 31, 2023 USD ($)	Apr. 24, 2023 MW	Mar. 06, 2023 USD ($)	Jan. 13, 2023 USD ($)	Aug. 25, 2022 USD ($) MW	May 01, 2022	Nov. 22, 2021 MW site	Jan. 16, 2020 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($)
Transmission Related Vegetation Management Programs | FERC | FE
Regulatory Matters [Line Items]
Utilities reclassification to operating expense														$ 105,000	$ 13,000
Pennsylvania | PPUC | Pennsylvania Companies
Regulatory Matters [Line Items]
Recovery period				5 years
Public utilities, settlement amount				$ 650
Pennsylvania | ENEC Phase IV | PPUC
Regulatory Matters [Line Items]
Public utilities, approved energy consumption reduction targets, cost recovery															$ 390,000
Pennsylvania | ENEC Phase IV | PPUC | ME
Regulatory Matters [Line Items]
Demand reduction targets															2.90%
Energy consumption reduction targets															3.10%
Pennsylvania | ENEC Phase IV | PPUC | PN
Regulatory Matters [Line Items]
Demand reduction targets															3.30%
Energy consumption reduction targets															3.00%
Pennsylvania | ENEC Phase IV | PPUC | Penn
Regulatory Matters [Line Items]
Demand reduction targets															2.00%
Energy consumption reduction targets															2.70%
Pennsylvania | ENEC Phase IV | PPUC | WP
Regulatory Matters [Line Items]
Demand reduction targets															2.50%
Energy consumption reduction targets															2.40%
Pennsylvania | New LTIP's | PPUC | Pennsylvania Companies
Regulatory Matters [Line Items]
Recovery period								5 years					5 years
Amount of requested rate increase								$ 572,000					$ 572,000
West Virginia | WVPSC | MP and PE
Regulatory Matters [Line Items]
Amount of requested rate increase			$ 17,000			$ 207,000
Requested amount of annual depreciation expense						$ 76,000			$ 76,000
Increase in annual amount of depreciation expense					$ 33,000
Recovery period for expenditures for cost recovery program			2 years
West Virginia | WVPSC | MP and PE | Subsequent Event
Regulatory Matters [Line Items]
Approved amount of rate increase (decrease)	$ 105,000
Increase in annual amount of depreciation expense	$ 33,000
West Virginia | WVPSC | MP and PE | Solar Generation Project
Regulatory Matters [Line Items]
Plant capacity (in MW's) | MW							30					50
Number of solar sites | site												5
Percent of subscriptions required prior to commencement											85.00%
Expected cost of the program															$ 110,000
Number of approved solar sites | site												3
West Virginia | ENEC | WVPSC | MP and PE
Regulatory Matters [Line Items]
Amount of requested rate increase			$ 167,500							$ 183,800
Under recovered amount, percent			9.90%							12.20%
Supplemental requested decrease			$ 267,000							$ 145,000
Approved amount of rate increase (decrease)		$ 55,400								$ 92,000
Recovery amounts		50,000
Approved ROE										4.00%
Plant capacity (in MW's) | MW										1,300
Deferred requested rate increase			92,000
Amount not recovered			$ 75,600
West Virginia | Expanded Net Energy Cost Through 2026 | WVPSC | MP and PE
Regulatory Matters [Line Items]
Approved amount of rate increase (decrease)		$ 255,000