Financing - Narrative (Details)	Mar. 31, 2022 USD ($)
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 7,655,000,000
Variable rate pollution control revenue bonds outstanding	1,500,000,000
MISSISSIPPI POWER CO
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	275,000,000
Variable rate pollution control revenue bonds outstanding	34,000,000
MISSISSIPPI POWER CO | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	125,000,000
ALABAMA POWER CO
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	1,250,000,000
Variable rate pollution control revenue bonds outstanding	789,000,000
GEORGIA POWER CO
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	1,750,000,000
Variable rate pollution control revenue bonds outstanding	672,000,000
Fixed rate pollution control revenue bonds outstanding	$ 330,000,000