INCOME TAXES - Reconciliation of Federal Statutory Income Tax Rate (Details)	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Reconciliation of federal statutory income tax rate to effective income tax rate
Federal statutory rate	21.00%	21.00%	21.00%
State income tax, net of federal deduction	3.60%	2.90%	7.80%
Changes in valuation allowance, net of federal benefit	1.90%	(0.30%)	(1.60%)
Employee stock plans' dividend deduction	(0.40%)	(0.50%)	(0.50%)
Non-deductible book depreciation	0.60%	0.70%	0.60%
Flowback of excess deferred income taxes	(3.90%)	(9.20%)	(6.60%)
AFUDC-Equity	(0.80%)	(1.10%)	(1.10%)
Federal PTCs	(2.80%)	(1.20%)	0.00%
ITC amortization	(1.20%)	(1.30%)	(1.30%)
Noncontrolling interests	0.60%	0.60%	0.50%
Other	(0.10%)	(0.20%)	0.00%
Effective income tax (benefit) rate	18.50%	11.40%	18.80%
Alabama Power
Reconciliation of federal statutory income tax rate to effective income tax rate
Federal statutory rate	21.00%	21.00%	21.00%
State income tax, net of federal deduction	5.00%	5.20%	4.80%
Changes in valuation allowance, net of federal benefit	0.00%	0.00%	0.00%
Employee stock plans' dividend deduction	0.00%	0.00%	0.00%
Non-deductible book depreciation	0.60%	0.70%	0.50%
Flowback of excess deferred income taxes	(5.30%)	(19.80%)	(1.90%)
AFUDC-Equity	(0.70%)	(1.20%)	(0.80%)
Federal PTCs	(0.10%)	0.00%	0.00%
ITC amortization	(0.10%)	(0.10%)	(0.10%)
Noncontrolling interests	0.00%	0.00%	0.00%
Other	0.00%	(0.20%)	0.30%
Effective income tax (benefit) rate	20.40%	5.60%	23.80%
Georgia Power
Reconciliation of federal statutory income tax rate to effective income tax rate
Federal statutory rate	21.00%	21.00%	21.00%
State income tax, net of federal deduction	1.70%	2.10%	3.30%
Changes in valuation allowance, net of federal benefit	3.10%	(0.60%)	3.20%
Employee stock plans' dividend deduction	0.00%	0.00%	0.00%
Non-deductible book depreciation	0.70%	0.80%	0.60%
Flowback of excess deferred income taxes	(2.20%)	(2.60%)	(9.60%)
AFUDC-Equity	(1.00%)	(1.20%)	(1.50%)
Federal PTCs	(3.70%)	(1.40%)	0.00%
ITC amortization	(0.20%)	(0.10%)	(0.10%)
Noncontrolling interests	0.00%	0.00%	0.00%
Other	(0.20%)	(0.30%)	0.00%
Effective income tax (benefit) rate	19.20%	17.70%	16.90%
Mississippi Power
Reconciliation of federal statutory income tax rate to effective income tax rate
Federal statutory rate	21.00%	21.00%	21.00%
State income tax, net of federal deduction	4.40%	4.90%	4.40%
Changes in valuation allowance, net of federal benefit	0.00%	0.00%	0.00%
Employee stock plans' dividend deduction	0.00%	0.00%	0.00%
Non-deductible book depreciation	0.30%	0.40%	0.30%
Flowback of excess deferred income taxes	(6.50%)	(10.20%)	(7.80%)
AFUDC-Equity	0.00%	0.00%	0.00%
Federal PTCs	0.00%	0.00%	0.00%
ITC amortization	0.00%	0.00%	0.00%
Noncontrolling interests	0.00%	0.00%	0.00%
Other	0.00%	0.10%	0.30%
Effective income tax (benefit) rate	19.20%	16.20%	18.20%
Southern Power
Reconciliation of federal statutory income tax rate to effective income tax rate
Federal statutory rate	21.00%	21.00%	21.00%
State income tax, net of federal deduction	(2.30%)	(0.70%)	1.90%
Changes in valuation allowance, net of federal benefit	0.00%	0.00%	0.00%
Employee stock plans' dividend deduction	0.00%	0.00%	0.00%
Non-deductible book depreciation	0.00%	0.00%	0.00%
Flowback of excess deferred income taxes	0.00%	0.00%	0.00%
AFUDC-Equity	0.00%	0.00%	0.00%
Federal PTCs	(17.20%)	(7.40%)	(6.60%)
ITC amortization	(26.40%)	(19.00%)	(17.20%)
Noncontrolling interests	17.10%	11.10%	8.40%
Other	0.20%	0.10%	(0.10%)
Effective income tax (benefit) rate	(7.60%)	5.10%	7.40%
Southern Company Gas
Reconciliation of federal statutory income tax rate to effective income tax rate
Federal statutory rate	21.00%	21.00%	21.00%
State income tax, net of federal deduction	7.00%	7.80%	6.40%
Changes in valuation allowance, net of federal benefit	0.00%	0.00%	0.00%
Employee stock plans' dividend deduction	0.00%	0.00%	0.00%
Non-deductible book depreciation	0.00%	0.00%	0.00%
Flowback of excess deferred income taxes	(2.20%)	(2.60%)	(2.50%)
AFUDC-Equity	0.00%	0.00%	0.00%
Federal PTCs	0.00%	0.00%	0.00%
ITC amortization	0.00%	0.00%	(0.10%)
Noncontrolling interests	0.00%	0.00%	0.00%
Other	0.00%	(0.60%)	(0.90%)
Effective income tax (benefit) rate	25.80%	25.60%	23.90%

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to deduction for dividend paid to employee stock ownership plan.

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