CONTINGENCIES, COMMITMENTS, AND GUARANTEES - MPC Other Matters (Details)	12 Months Ended				60 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2025 USD ($)	Jan. 15, 2024 USD ($)	Jul. 30, 2022 claim
Loss Contingencies [Line Items]
Period costs	$ 90,000,000	$ 36,000,000
Mississippi Power
Loss Contingencies [Line Items]
Period costs	0	0
Kemper County energy facility assets, net | Mississippi Power
Loss Contingencies [Line Items]
Pre-tax charge to income	17,000,000	15,000,000	$ 11,000,000
After tax charge to income	$ 12,000,000	$ 12,000,000	$ 8,000,000
Plant Daniel | Mississippi Power
Loss Contingencies [Line Items]
Plant units | claim							2
Plant Daniel Unit, Primary | Mississippi Power
Loss Contingencies [Line Items]
Plant units | claim							1
Scenario, Forecast | Kemper County energy facility assets, net | Mississippi Power | Maximum
Loss Contingencies [Line Items]
Period costs					$ 15,000,000
Scenario, Forecast | Plant Daniel | Mississippi Power
Loss Contingencies [Line Items]
Payments to acquire businesses						$ 1
Scenario, Forecast | Plant Daniel | Gulf Power
Loss Contingencies [Line Items]
Percent ownership in individual unit						100.00%
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Gulf Power
Loss Contingencies [Line Items]
Proceeds from divestiture of businesses, amount held back				$ 75,000,000