Initial Assumed Percentage Payout At End Of Performance Period

No definition available.

Name:	so_InitialAssumedPercentagePayoutAtEndOfPerformancePeriod
Namespace Prefix:	so_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum Percentage of transfer performance shares to common stock based on actual Shareholder Return.

+ References

No definition available.

+ Details

Name:	so_MaximumPercentageOfTransferPerformanceSharesToCommonStockBasedOnActualShareholderReturn
Namespace Prefix:	so_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Minimum Percentage of transfer performance shares to common stock based on actual Shareholder Return.

+ References

No definition available.

+ Details

Name:	so_MinimumPercentageOfTransferPerformanceSharesToCommonStockBasedOnActualShareholderReturn
Namespace Prefix:	so_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Number Of Additional Types Of Performance Share Units

+ References

No definition available.

+ Details

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

- Definition

Number Of Employees Participating in Stock Option and Performance Share Units Program

+ References

No definition available.

+ Details

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

- Definition

Percentage Of Total Performance Share Units Granted

+ References

No definition available.

+ Details

Name:	so_PercentageOfTotalPerformanceShareUnitsGranted
Namespace Prefix:	so_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award award expiration period.

+ References

No definition available.

+ Details

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

- Definition

Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period

+ References

No definition available.

+ Details

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

- Definition

Share based compensation arrangement by share based payment award number of shares reserved for issuance pursuant to stock based compensation plan.

+ References

No definition available.

+ Details

Name:	so_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesReservedForIssuancePursuantToStockBasedCompensationPlan
Namespace Prefix:	so_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Share based compensation arrangement by share based payment award fair value assumptions weighted average grant date fair value.

+ References

No definition available.

+ Details

Name:	so_ShareBasedCompensationArrangementbyShareBasedPaymentAwardFairValueAssumptionsWeightedAverageGrantDateFairValue
Namespace Prefix:	so_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Stock issued during period shares company investment plan and employee and director stock plans.

+ References

No definition available.

+ Details

Name:	so_StockIssuedDuringPeriodSharesCompanyInvestmentPlanAndEmployeeAndDirectorStockPlans
Namespace Prefix:	so_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Undistributed retained earnings of the subsidiaries.

+ References

No definition available.

+ Details

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

- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 14.F)
-URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 14
-Section F

+ Details

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

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Antidilution
-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Diluted Earnings Per Share
-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Contingent Stock Agreement
-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate proceeds received by the entity during the annual period from exercises of stock or unit options and conversion of similar instruments granted under equity-based payment arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (j)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

Unrecognized cost of unvested share-based compensation awards.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

+ References

+ Details

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

- Definition

The total cash inflow associated with the amount received from holders to acquire the entity's shares under incentive and share awards, including stock option exercises. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3255-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(3)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)-(ii)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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

- Definition

Net number of share options (or share units) granted during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

+ References

+ Details

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

- Definition

As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

As of the balance sheet date, the weighted-average exercise price for outstanding stock options that are fully vested or expected to vest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

+ References

No definition available.

+ Details

Name:	us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30
-Article 5

+ Details

Name:	us-gaap_StockRepurchasedDuringPeriodShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30, 31
-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=so_EPSbasedandROEbasedPerformanceShareUnitsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=so_ROEbasedPortionOfThePerformanceSharePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=so_TSRbasedPortionOfThePerformanceSharePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AwardTypeAxis=so_EPSbasedPortionOfThePerformanceSharePlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementClassOfStockAxis=so_SouthernCompanyCommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=so_AlabamaPowerMember
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_GulfPowerMember
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:	us-gaap_StatementEquityComponentsAxis=us-gaap_ParentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Common Stock and Stock Compensation - Textual (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Mar. 02, 2015 shares	Dec. 31, 2015 USD ($) Employee share_unit_type $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) $ / shares shares
Share-based Compensation [Abstract]
Stock Issued During Period, Shares, Southern Investment Plan and employee and director stock plans \| shares		6,600,000
Stock Issued During Period, Value, Southern Investment Plan and employee and director stock plans		$ 256
Stock Repurchased During Period, Shares \| shares	2,600,000
Stock Repurchased During Period, Value		$ 115
Share-based compensation arrangement by Share-based payment award, number of shares reserved for issuance, pursuant to Stock-based compensation plan \| shares		106,000,000
Number Of Employees Participating in Stock Option and Performance Share Units Program \| Employee		5,405
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares			$ 2.20	$ 2.93
Weighted average remaining contractual term for options outstanding		6 years
Aggregate intrinsic value for options outstanding		$ 209
Aggregate intrinsic value for options exercisable		162
Total compensation cost for award recognized in income		6	$ 27	$ 25
Total compensation cost for award recognized in income, tax benefit		2	10	10
Total intrinsic value of options exercised		48	125	77
Actual tax benefit for the tax deduction from stock option exercised		19	48	30
Cash received from issuance related to option exercise		$ 154	$ 400	$ 204
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		200.00%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term		6 years
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) \| shares		1,000,000	7,000,000
Undistributed retained earnings of the subsidiaries		$ 7,000
Performance Shares [Member]
Share-based Compensation [Abstract]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 46.38	$ 37.54	$ 40.50
Total unrecognized compensation cost related to award		$ 33
Total unrecognized compensation cost related to award, weighted average period		19 months
Total compensation cost for award recognized in income		$ 88	$ 33	$ 31
Total compensation cost for award recognized in income, tax benefit		$ 34	$ 13	12
Vesting period of performance share units issued under Performance Share Plan		3 years
Performance share units, unvested \| shares		2,480,392	1,830,381
Performance share units, granted \| shares		1,542,653
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares) \| shares		812,740
Performance unit shares, forfeited \| shares		79,902
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number (in shares) \| shares		227,515
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Exercise Price (in dollars per share) \| $ / shares		$ 46.80
Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant		10 years
EPS-based and ROE-based Performance Share Plan [Member]
Share-based Compensation [Abstract]
Number Of Additional Types Of Performance Share Units \| share_unit_type		2
Initial Assumed Percentage Payout At End Of Performance Period		100.00%
ROE-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
TSR-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		50.00%
EPS-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Maximum [Member]
Share-based Compensation [Abstract]
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased \| shares	20,000,000
Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period		3 years
Southern Company Common Stock [Member]
Share-based Compensation [Abstract]
Remaining shares available for awards \| shares		14,000,000
Alabama Power [Member]
Share-based Compensation [Abstract]
Number Of Employees Participating in Stock Option and Performance Share Units Program \| Employee		881
Aggregate intrinsic value for options outstanding		$ 33
Aggregate intrinsic value for options exercisable		26
Total intrinsic value of options exercised		8	$ 21	11
Actual tax benefit for the tax deduction from stock option exercised		3	8	4
Alabama Power [Member] \| Performance Shares [Member]
Share-based Compensation [Abstract]
Total unrecognized compensation cost related to award		$ 4
Total unrecognized compensation cost related to award, weighted average period		19 months
Total compensation cost for award recognized in income		$ 13	5	5
Total compensation cost for award recognized in income, tax benefit		$ 5	$ 2	$ 2
Vesting period of performance share units issued under Performance Share Plan		3 years
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		200.00%
Performance share units, granted \| shares		214,709	176,070	141,355
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 46.42	$ 37.54	$ 40.50
Alabama Power [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant		10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures \| shares			2,027,298	1,319,038
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares			$ 2.20	$ 2.93
Alabama Power [Member] \| EPS-based and ROE-based Performance Share Plan [Member]
Share-based Compensation [Abstract]
Number Of Additional Types Of Performance Share Units \| share_unit_type		2
Initial Assumed Percentage Payout At End Of Performance Period		100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 47.78
Alabama Power [Member] \| ROE-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Alabama Power [Member] \| TSR-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		50.00%
Alabama Power [Member] \| EPS-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Alabama Power [Member] \| Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period		3 years
Georgia Power [Member]
Share-based Compensation [Abstract]
Number Of Employees Participating in Stock Option and Performance Share Units Program \| Employee		1,002
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures \| shares			2,034,150	1,509,662
Aggregate intrinsic value for options outstanding		$ 45
Aggregate intrinsic value for options exercisable		38
Total intrinsic value of options exercised		9	$ 19	$ 16
Actual tax benefit for the tax deduction from stock option exercised		$ 4	7	6
Vesting period of performance share units issued under Performance Share Plan		3 years
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		200.00%
Georgia Power [Member] \| Performance Shares [Member]
Share-based Compensation [Abstract]
Total unrecognized compensation cost related to award		$ 4
Total unrecognized compensation cost related to award, weighted average period		19 months
Total compensation cost for award recognized in income		$ 15	6	6
Total compensation cost for award recognized in income, tax benefit		$ 6	$ 2	$ 2
Performance share units, granted \| shares		236,804	176,224	161,240
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 46.41	$ 37.54	$ 40.50
Georgia Power [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant		10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares			$ 2.20	$ 2.93
Georgia Power [Member] \| EPS-based and ROE-based Performance Share Plan [Member]
Share-based Compensation [Abstract]
Number Of Additional Types Of Performance Share Units \| share_unit_type		2
Initial Assumed Percentage Payout At End Of Performance Period		100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 47.78
Georgia Power [Member] \| ROE-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Georgia Power [Member] \| TSR-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		50.00%
Georgia Power [Member] \| EPS-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Georgia Power [Member] \| Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period		3 years
Gulf Power [Member]
Share-based Compensation [Abstract]
Number Of Employees Participating in Stock Option and Performance Share Units Program \| Employee		198
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures \| shares			432,371	285,209
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares			$ 2.20	$ 2.93
Aggregate intrinsic value for options outstanding		$ 7
Aggregate intrinsic value for options exercisable		5
Total intrinsic value of options exercised		2	$ 5	$ 2
Actual tax benefit for the tax deduction from stock option exercised		$ 1	$ 2	$ 1
Vesting period of performance share units issued under Performance Share Plan		3 years
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		200.00%
Gulf Power [Member] \| Performance Shares [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Fair Value Assumptions Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 46.38	$ 37.54	$ 40.50
Total unrecognized compensation cost related to award		$ 2
Total unrecognized compensation cost related to award, weighted average period		19 months
Total compensation cost for award recognized in income		$ 2	$ 1	$ 1
Total compensation cost for award recognized in income, tax benefit		$ 1
Performance share units, granted \| shares		48,962	37,829	30,627
Gulf Power [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant		10 years
Gulf Power [Member] \| EPS-based and ROE-based Performance Share Plan [Member]
Share-based Compensation [Abstract]
Number Of Additional Types Of Performance Share Units \| share_unit_type		2
Initial Assumed Percentage Payout At End Of Performance Period		100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 47.75
Gulf Power [Member] \| ROE-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Gulf Power [Member] \| TSR-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		50.00%
Gulf Power [Member] \| EPS-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Gulf Power [Member] \| Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period		3 years
Mississippi Power [Member]
Share-based Compensation [Abstract]
Number Of Employees Participating in Stock Option and Performance Share Units Program \| Employee		231
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures \| shares			578,256	345,830
Vesting period of performance share units issued under Performance Share Plan		3 years
Mississippi Power [Member] \| Performance Shares [Member]
Share-based Compensation [Abstract]
Total unrecognized compensation cost related to award		$ 1
Total unrecognized compensation cost related to award, weighted average period		19 months
Total compensation cost for award recognized in income		$ 4	$ 2	$ 2
Total compensation cost for award recognized in income, tax benefit		$ 2	$ 1	$ 1
Minimum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		0.00%
Maximum Percentage of transfer performance shares to common stock based on actual Total Shareholder Return		200.00%
Performance share units, granted \| shares		53,909	49,579	36,769
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 46.41	$ 37.54	$ 40.50
Mississippi Power [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Option expiration period from date of grant		10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares			$ 2.20	$ 2.93
Aggregate intrinsic value for options outstanding		$ 7
Aggregate intrinsic value for options exercisable		5
Total intrinsic value of options exercised		3	$ 5	$ 3
Actual tax benefit for the tax deduction from stock option exercised		$ 1	$ 2	$ 1
Mississippi Power [Member] \| EPS-based and ROE-based Performance Share Plan [Member]
Share-based Compensation [Abstract]
Number Of Additional Types Of Performance Share Units \| share_unit_type		2
Initial Assumed Percentage Payout At End Of Performance Period		100.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) \| $ / shares		$ 47.77
Mississippi Power [Member] \| ROE-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Mississippi Power [Member] \| TSR-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		50.00%
Mississippi Power [Member] \| EPS-based Portion Of The Performance Share Plan [Member]
Share-based Compensation [Abstract]
Percentage Of Total Performance Share Units Granted		25.00%
Mississippi Power [Member] \| Maximum [Member] \| Stock Options [Member]
Share-based Compensation [Abstract]
Share Based Compensation Arrangement by Share Based Payment Award Exercisable Period		3 years
Parent [Member]
Share-based Compensation [Abstract]
Stock Repurchased During Period, Value		$ 115