Financing and Leases - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2023	May 31, 2023	Apr. 30, 2023
Debt Instrument [Line Items]
Expires, 2028	$ 6,400
Line of credit facility, maximum borrowing capacity	7,505
Variable rate pollution control revenue bonds outstanding	1,400
Southern Company parent(a)
Debt Instrument [Line Items]
Expires, 2028	1,850	$ 1,850
Line of credit facility, maximum borrowing capacity	2,000	150
MISSISSIPPI POWER CO
Debt Instrument [Line Items]
Expires, 2028	0
Line of credit facility, maximum borrowing capacity	275	150
Variable rate pollution control revenue bonds outstanding	69
Nicor Gas
Debt Instrument [Line Items]
Expires, 2028	700
Line of credit facility, maximum borrowing capacity		100	$ 250
ALABAMA POWER CO
Debt Instrument [Line Items]
Expires, 2028	700
Line of credit facility, maximum borrowing capacity	1,250
Variable rate pollution control revenue bonds outstanding	492
Fixed rate pollution control revenue bonds outstanding	120
GEORGIA POWER CO
Debt Instrument [Line Items]
Expires, 2028	1,750
Line of credit facility, maximum borrowing capacity	1,750
Variable rate pollution control revenue bonds outstanding	819
Fixed rate pollution control revenue bonds outstanding	225
Southern Company and Southern Power
Debt Instrument [Line Items]
Expires, 2028	2,450	2,450
SOUTHERN POWER CO
Debt Instrument [Line Items]
Expires, 2028	600	$ 600
Line of credit facility, maximum borrowing capacity	$ 600