Regulatory Matters - MPC (Details) - USD ($) $ in Millions					1 Months Ended
	Jul. 31, 2023	Apr. 04, 2023	Apr. 03, 2023	Mar. 31, 2023	Jul. 31, 2022
Loss Contingencies [Line Items]
Minimum annual accrual, amount			$ 8
MISSISSIPPI POWER CO
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
Loss Contingencies [Line Items]
Approved rate increase (decrease)		$ 3
MISSISSIPPI POWER CO | Municipal And Rural Associations Tariff
Loss Contingencies [Line Items]
Requested rate increase (decrease) amount					$ 23
MISSISSIPPI POWER CO | Municipal And Rural Associations Tariff | Subsequent Event
Loss Contingencies [Line Items]
Requested rate increase (decrease) amount	$ 16
Customer refund payments	$ 6