REGULATORY MATTERS - Pennsylvania and West Virginia (Details) $ in Millions										1 Months Ended	3 Months Ended
	Dec. 29, 2021 USD ($)	Dec. 27, 2021 USD ($)	Dec. 17, 2021 USD ($)	Nov. 22, 2021 USD ($) plant MW	Nov. 18, 2021 USD ($)	Aug. 27, 2021 USD ($)	Dec. 30, 2020 USD ($)	Aug. 30, 2019 USD ($)	Jun. 01, 2019 proposal MW	Mar. 31, 2016 USD ($)	Dec. 31, 2021 USD ($)	Jun. 18, 2020
Pennsylvania | PPUC
Regulatory Matters [Line Items]
Revised requested rate increase					$ 61.0
Pennsylvania | PPUC | Utilities and FET
Regulatory Matters [Line Items]
Pre-tax charges											$ 61.0
Pennsylvania | PPUC | Penn | ENEC Phase IV
Regulatory Matters [Line Items]
Approved demand reduction targets												2.00%
Approved energy consumption reduction targets												2.70%
Pennsylvania | PPUC | WP | ENEC Phase IV
Regulatory Matters [Line Items]
Approved demand reduction targets												2.50%
Approved energy consumption reduction targets												2.40%
Pennsylvania | PPUC | Pennsylvania Companies | DSP
Regulatory Matters [Line Items]
Number of RFP's | proposal									2
Project term									2 years
New hourly priced default service threshold (in MW's) | MW									0.1
Pennsylvania | PPUC | Pennsylvania Companies | DSP | 3 Month Period
Regulatory Matters [Line Items]
Energy contract term									3 months
Pennsylvania | PPUC | Pennsylvania Companies | DSP | 12 Month Period
Regulatory Matters [Line Items]
Energy contract term									12 months
Pennsylvania | PPUC | Pennsylvania Companies | DSP | 24 Month Period
Regulatory Matters [Line Items]
Energy contract term									24 months
Pennsylvania | PPUC | Pennsylvania Companies | EE&C
Regulatory Matters [Line Items]
Approved amount of rate increase (decrease)										$ 390.0
Pennsylvania | PPUC | Pennsylvania Companies | New LTIP's
Regulatory Matters [Line Items]
Cost recovery period								5 years
Requested rate increase (decrease)								$ 572.0
Pennsylvania | PPUC | PN | ENEC Phase IV
Regulatory Matters [Line Items]
Approved demand reduction targets												3.30%
Approved energy consumption reduction targets												3.00%
Pennsylvania | PPUC | ME | ENEC Phase IV
Regulatory Matters [Line Items]
Approved demand reduction targets												2.90%
Approved energy consumption reduction targets												3.10%
West Virginia | WVPSC | MP and PE
Regulatory Matters [Line Items]
Number of solar generation sites | plant				5
Solar generation plant capacity (in MW's) | MW				50
West Virginia | WVPSC | MP and PE | Ft. Martin and Harrison Power Stations
Regulatory Matters [Line Items]
Requested rate increase (decrease)			$ 142.0
Requested annual rate increase			$ 3.0
West Virginia | WVPSC | MP and PE | Solar Generation Project
Regulatory Matters [Line Items]
Expected cost of the program				$ 100.0
West Virginia | WVPSC | MP and PE | ENEC
Regulatory Matters [Line Items]
Approved amount of rate increase (decrease)							$ (7.7)
Requested rate increase (decrease)						$ 19.6	$ (2.6)
Requested rate increase (decrease) (percent)						1.50%
Supplemental requested decrease						$ (7.7)
Approved amount of rate offset	$ 2.9
West Virginia | WVPSC | MP and PE | Integrated Resource Plan
Regulatory Matters [Line Items]
Approved amount of rate increase (decrease)	$ 19.6
West Virginia | WVPSC | MP and PE | Vegetation Management Surcharge Rates
Regulatory Matters [Line Items]
Approved amount of rate increase (decrease)		$ 16.0
Requested rate increase (decrease)						$ 16.0
Surcharge period		2 years