Regulatory Matters - MPC (Details) - USD ($) $ in Millions	Apr. 04, 2023	Apr. 03, 2023	Mar. 31, 2023
Subsequent Event
Loss Contingencies [Line Items]
Minimum annual accrual, amount		$ 8
MISSISSIPPI POWER CO | Subsequent Event
Loss Contingencies [Line Items]
Approved rate increase (decrease)	$ 12
MISSISSIPPI POWER CO | Ad Valorem Tax Adjustment
Loss Contingencies [Line Items]
Requested rate increase (decrease) amount			$ 7
MISSISSIPPI POWER CO | ECO Plan | Subsequent Event
Loss Contingencies [Line Items]
Approved rate increase (decrease)	$ 3