Business Combination, Option To Purchase, Period

No definition available.

Name:	so_BusinessCombinationOptionToPurchasePeriod
Namespace Prefix:	so_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Plant Units

+ References

No definition available.

+ Details

Name:	so_PublicUtilitiesPlantUnits
Namespace Prefix:	so_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Undivided Ownership Interest, Ownership Interest In Individual Unit

+ References

No definition available.

+ Details

Name:	so_UndividedOwnershipInterestOwnershipInterestInIndividualUnit
Namespace Prefix:	so_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Estimated amount of loss resulting from an adverse tax position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (d)(3)
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319

+ Details

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

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

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI https://asc.fasb.org/extlink&oid=126975305&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3213-108585

+ Details

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

- Definition

The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3179-108585

+ Details

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

- Details

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

- Details

Name:	us-gaap_PublicUtilityAxis=so_PlantDanielUnitPrimaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PublicUtilityAxis=so_PlantDanielUnits1And2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis=so_GulfPowerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Contingencies - Other Matters (Details)			12 Months Ended	60 Months Ended
Contingencies - Other Matters (Details)	Aug. 31, 2022 USD ($)	Jul. 12, 2022 USD ($) claim	Dec. 31, 2019 USD ($)	Jan. 15, 2024 USD ($)
MISSISSIPPI POWER CO
Loss Contingencies [Line Items]
Estimate of possible loss	$ 28,000,000
Plant Daniel Unit, Primary \| MISSISSIPPI POWER CO
Loss Contingencies [Line Items]
Plant units \| claim		1
Plant Daniel Units 1 And 2 \| GULF POWER CO
Loss Contingencies [Line Items]
Percent ownership in individual unit		100.00%
Plant Daniel Units 1 And 2 \| MISSISSIPPI POWER CO
Loss Contingencies [Line Items]
Plant units \| claim		2
Scenario, Forecast \| Plant Daniel Units 1 And 2 \| MISSISSIPPI POWER CO
Loss Contingencies [Line Items]
Payments to acquire businesses				$ 1
Business combination, option to purchase, period				120 days
Disposal Group, Disposed of by Sale \| GULF POWER CO
Loss Contingencies [Line Items]
Proceeds from divestiture of businesses, amount held back		$ 75,000,000	$ 75,000,000