Effective Income Tax Rate Reconciliation, Tax Credit, Production, Amount

No definition available.

Name:	so_EffectiveIncomeTaxRateReconciliationTaxCreditProductionAmount
Namespace Prefix:	so_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Expenditures for Purchased Tax Credits

+ References

No definition available.

+ Details

Name:	so_ExpendituresForPurchasedTaxCredits
Namespace Prefix:	so_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Proceeds From Tax Credit Transfer

+ References

No definition available.

+ Details

Name:	so_ProceedsFromTaxCreditTransfer
Namespace Prefix:	so_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Reduction in Tax Basis of Assets Under Option One.

+ References

No definition available.

+ Details

Name:	so_ReductionInTaxBasisOfAssetsUnderOptionOne
Namespace Prefix:	so_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

State Investment Tax Credit Carryforward

+ References

No definition available.

+ Details

Name:	so_StateInvestmentTaxCreditCarryforward
Namespace Prefix:	so_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

+ Details

Name:	us-gaap_DeferredTaxAssetsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_IncomeTaxContingencyLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount 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 increase (decrease) in the valuation allowance for deferred tax assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 231
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-231

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12A
-Subparagraph (a)(6)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12A

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

+ Details

Name:	us-gaap_IncomeTaxReconciliationChangeInDeferredTaxAssetsValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12A
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12A

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

+ Details

Name:	us-gaap_IncomeTaxReconciliationTaxCreditsInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The portion of the valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from net operating loss carryforwards for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

+ Details

Name:	us-gaap_OperatingLossCarryforwardsValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from tax credit carryforwards for which it is more likely than not that a tax benefit will not be realized.

+ References

+ Details

Name:	us-gaap_TaxCreditCarryforwardValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	dei_LegalEntityAxis=so_SouthernPowerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	so_DeferredTaxAssetsLiabilitiesAxis=so_InvestmentTaxAndOtherCreditCarryforwardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	so_DeferredTaxAssetsLiabilitiesAxis=so_ProductionTaxCreditCarryforwardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=so_GeorgiaPowerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=so_MississippiPowerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=so_SouthernCompanyGasMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_StateAndLocalJurisdictionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	so_ReclassificationOutOfBalanceSheetLocationAxis=so_DeferredChargesRelatedToIncomeTaxesCurrentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	so_DeferredTaxAssetsLiabilitiesAxis=so_UnrealizedTaxCreditsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_MS
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_OK
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=stpr_FL
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Line Items]
Deferred income tax assets	$ 7,593	$ 7,886
State investment tax credit carryforward	515
Operating loss carryforwards, valuation allowance	82
Southern Power
Income Tax Disclosure [Line Items]
Deferred income tax assets	$ 638	773
Percentage reduction in tax basis of assets	50.00%
Operating loss carryforwards, valuation allowance	$ 21
Proceeds From Tax Credit Transfer	24
Southern Power \| ITCs and other credits carryforward
Income Tax Disclosure [Line Items]
Reduction in income tax expense, investment tax credits	71	332	$ 49
Southern Power \| Production Tax Credit Carryforward
Income Tax Disclosure [Line Items]
Effective income tax rate reconciliation, tax credit, production, amount	32	26	27
Georgia Power
Income Tax Disclosure [Line Items]
Deferred income tax assets	3,564	3,718
State investment tax credit carryforward	472
Georgia Power \| Production Tax Credit Carryforward
Income Tax Disclosure [Line Items]
Payments for transferred tax credit	131	39
Mississippi Power
Income Tax Disclosure [Line Items]
Deferred income tax assets	358	382
Southern Company Gas
Income Tax Disclosure [Line Items]
Deferred income tax assets	493	377
State and Local Jurisdiction
Income Tax Disclosure [Line Items]
Valuation allowance	161
Change in valuation allowance	101
State and Local Jurisdiction \| Georgia Power
Income Tax Disclosure [Line Items]
Valuation allowance	124
Change in valuation allowance	64
Proceeds From Tax Credit Transfer	11
State and Local Jurisdiction \| Georgia Power \| ITCs and other credits carryforward
Income Tax Disclosure [Line Items]
Reduction in income tax expense, investment tax credits	44	$ 49	53
Deferred Charges Related To Income Taxes, Current \| Other Noncurrent Assets \| Southern Power \| Unrealized Tax Credits
Income Tax Disclosure [Line Items]
Deferred income tax assets	0		$ 17
Mississippi \| Mississippi Power
Income Tax Disclosure [Line Items]
Operating loss carryforwards, valuation allowance	32
Oklahoma \| Southern Power
Income Tax Disclosure [Line Items]
Operating loss carryforwards, valuation allowance	11
Florida \| Southern Power
Income Tax Disclosure [Line Items]
Operating loss carryforwards, valuation allowance	$ 10