Loss Contingency, Number Of Additional Plaintiffs

No definition available.

Name:	so_LossContingencyNumberOfAdditionalPlaintiffs
Namespace Prefix:	so_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Public Utilities, Underpayment Of Refunds

+ References

No definition available.

+ Details

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

- Definition

Amount of litigation expense, including but not limited to legal, forensic, accounting, and investigative fees.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementExpense
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 total number of new claims filed pertaining to a loss contingency during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

+ Details

Name:	us-gaap_LossContingencyNewClaimsFiledNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of defendants named in a legal action.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingencyNumberOfDefendants
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of plaintiffs that have filed claims pertaining to a loss contingency.

+ References

No definition available.

+ Details

Name:	us-gaap_LossContingencyNumberOfPlaintiffs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of pending claims pertaining to a loss contingency.

+ References

+ Details

Name:	us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_LitigationStatusAxis=us-gaap_PendingLitigationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=so_ShareholderDerivativeLawsuitsMember
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:	srt_LitigationCaseAxis=so_ClassActionLawsuitMember
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:	srt_LitigationCaseAxis=so_PurportedViolationsOfMississippiConsumerProtectionActMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Contingencies - General Litigation Matters (Details) - Pending Litigation $ in Millions				1 Months Ended	12 Months Ended
	Mar. 11, 2022 USD ($)	Feb. 07, 2022 claim	Oct. 08, 2021 claim	Mar. 31, 2019 plaintiff	Dec. 31, 2018 USD ($) plaintiff defendant	Mar. 09, 2022 claim	Dec. 31, 2017 claim
Shareholder Derivative Lawsuits
Loss Contingencies [Line Items]
Pending number of claims							2
Settlement expense \| $	$ 4.5
GEORGIA POWER CO \| Class Action Lawsuit
Loss Contingencies [Line Items]
Pending number of claims						4
Complaints filed		4	3
MISSISSIPPI POWER CO \| Purported Violations of Mississippi Consumer Protection Act
Loss Contingencies [Line Items]
Number of plaintiffs \| plaintiff					10
Number of defendants \| defendant					3
Number of additional plaintiffs \| plaintiff				4
Underpayment of refunds \| $					$ 23.5