Description of the Plan (Details)	12 Months Ended
Dec. 31, 2025 USD ($)
EBP, Description of Plan [Line Items]
Term or benefit payment receivable	20 years
Term of dividend payable	90 days
EBP 002
EBP, Description of Plan [Line Items]
Percentage of eligible compensation	50.00%
Employer contribution matching percentage	85.00%
Participant compensation matched	6.00%
Investment increments	1.00%
Fund borrowing minimum	$ 1,000
Maximum borrowing amount	$ 50,000
Note receivable, total borrowing percentage	50.00%
Note receivable, borrowing term for primary residence	15 years
EBP, Participant Contribution, Automatic, Deferral Rate	6.00%
Minimum \| EBP 002
EBP, Description of Plan [Line Items]
Note receivable, borrowing term	12 months
Maximum \| EBP 002
EBP, Description of Plan [Line Items]
Note receivable, borrowing term	60 months

EBP, Benefit Payments, Annual Installments Or Lump Sum Receivable, Term

No definition available.

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

- Definition

EBP, Benefit Payments, Dividend Payable, Term

+ References

No definition available.

+ Details

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

- Definition

EBP, Investment Contribution, Minimum Increment, Percent

+ References

No definition available.

+ Details

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

- Definition

EBP, Note Receivable From Participant, Account, Borrowing Term

+ References

No definition available.

+ Details

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

- Definition

EBP, Note Receivable From Participant, Account, Primary Residence, Maximum Borrowing Term

+ References

No definition available.

+ Details

Name:	so_EBPNoteReceivableFromParticipantAccountPrimaryResidenceMaximumBorrowingTerm
Namespace Prefix:	so_
Data Type:	xbrli:durationItemType
Balance Type:	na
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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 962
-SubTopic 205
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478416/962-205-50-1

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanDescriptionOfPlanLineItems
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of employer matching contribution on eligible participant contribution to employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 962
-SubTopic 325
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478873/962-325-55-17

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanEmployerContributionMatchingPercentage
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of participant compensation eligible for employer matching contribution for participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanEmployerContributionParticipantCompensationMatchedPercentage
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of maximum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow.

+ References

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanNoteReceivableFromParticipantAccountMaximumBorrowingAmount
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of maximum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow to total participant account balance.

+ References

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanNoteReceivableFromParticipantAccountMaximumBorrowingToTotalAccountPercentage
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of minimum account balance that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)) can borrow.

+ References

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanNoteReceivableFromParticipantAccountMinimumBorrowingAmount
Namespace Prefix:	us-gaap-ebp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of eligible compensation contributed for participant automatically enrolled in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)).

+ References

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanParticipantContributionAutomaticDeferralRate
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of maximum pretax annual compensation that participant in employee stock purchase, saving, or similar plan (employee benefit plan (EBP)), is permitted to contribute to total pretax annual compensation.

+ References

+ Details

Name:	us-gaap-ebp_EmployeeBenefitPlanParticipantContributionPretaxMaximumAnnualCompensationToTotalCompensationPercentage
Namespace Prefix:	us-gaap-ebp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=so_EBP002Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: