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Financing - Textual (Details) (USD $)
 1 Months Ended 12 Months Ended 0 Months Ended 1 Months Ended 12 Months Ended
Jun. 30, 2014
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Feb. 20, 2014
Feb. 28, 2014
loan
Jan. 31, 2014
Jan. 31, 2015
May 31, 2014
Sep. 30, 2013
Dec. 31, 2011
Dec. 11, 2014
Jul. 31, 2014
Apr. 30, 2014
Sep. 30, 2014
Feb. 28, 2013
Oct. 31, 2014
Oct. 09, 2014
Jan. 04, 2014
Mar. 31, 2012
Aug. 31, 2014
Nov. 30, 2013
Financing (Textual) [Abstract]                                            
Proceeds from issuance of junior subordinated notes   $ 206,000,000us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrustCurrent $ 206,000,000us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrustCurrent                                      
Other Long-term Debt   4,719,000,000us-gaap_OtherLongTermDebt 3,503,000,000us-gaap_OtherLongTermDebt                                      
Senior notes, current   2,375,000,000us-gaap_SeniorNotesCurrent 428,000,000us-gaap_SeniorNotesCurrent                                      
Other Long-term Debt   775,000,000us-gaap_OtherLongTermDebtCurrent 12,000,000us-gaap_OtherLongTermDebtCurrent                                      
Long term debt and capital lease obligations, maturities in 2014   3,330,000,000so_LongTermDebtAndCapitalLeaseObligationMaturitiesRePaymentsInNextTwelveMonths                                        
Long term debt and capital lease obligations, maturities in 2015   1,830,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearTwo                                        
Long term debt and capital lease obligations, maturities in 2016   1,550,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearThree                                        
Long Term Debt and Capital Lease Obligation Maturities Repayments in Year Four   862,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearFour                                        
Long term debt and capital lease obligations, maturities in 2018   1,210,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearFive                                        
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months   2,375,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths 2,375,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths                                      
Long-term debt maturities, 2016   1,360,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo 1,360,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo                                      
Long-term debt maturities, 2016   1,495,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree 1,095,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree                                      
Long-term Debt, Maturities, Repayments of Principal in Year Five   1,175,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive 825,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive                                      
Long-term Debt, Maturities, Repayments of Principal in Year Four   850,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour 850,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour                                      
Description of variable rate basis one-month one-month                                        
Bank loans, period of extension 90 days                                          
Aggregate Principal Amount Of Floating Rate Bank Loan 250,000,000so_AggregatePrincipalAmountOfFloatingRateBankLoan                                          
Ratio of indebtedness to capitalization, debt covenant, required   65.00%so_RatioOfIndebtednessToCapitalizationCovenant                                        
Senior Notes outstanding   18,200,000,000us-gaap_SeniorNotes 17,300,000,000us-gaap_SeniorNotes                                      
Derivative, Notional Amount   2,050,000,000invest_DerivativeNotionalAmount                                        
Capitalized lease obligations   159,000,000us-gaap_CapitalLeaseObligations 163,000,000us-gaap_CapitalLeaseObligations                                      
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment   24,059,000,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment 23,059,000,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment                                      
Unused credit with banks   5,177,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity                                        
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support   1,800,000,000so_AmountOfVariableRatePollutionControlRevenueBondsOutstandingRequiringLiquiditySupport                                        
Remarketed pollution control bonds   476,000,000so_RemarketedPollutionControlBonds                                        
Long-term Pollution Control Bond, Current   152,000,000us-gaap_LongtermPollutionControlBondCurrent 0us-gaap_LongtermPollutionControlBondCurrent                                      
Common Stock, Shares, Issued   909,000,000us-gaap_CommonStockSharesIssued 893,000,000us-gaap_CommonStockSharesIssued                                      
Proceeds from Issuance of Common Stock   806,000,000us-gaap_ProceedsFromIssuanceOfCommonStock 695,000,000us-gaap_ProceedsFromIssuanceOfCommonStock 397,000,000us-gaap_ProceedsFromIssuanceOfCommonStock                                    
Short-term Debt   803,000,000us-gaap_ShortTermBorrowings 1,482,000,000us-gaap_ShortTermBorrowings                                      
Commitment fee percentage (less than 1/4 of 1%)   0.25%us-gaap_LineOfCreditFacilityCommitmentFeePercentage                                        
Trust Preferred Securities Subject to Mandatory Redemption [Member]                                            
Financing (Textual) [Abstract]                                            
Preferred securities, outstanding   200,000,000us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsMaximumAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember		 200,000,000us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsMaximumAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember		                                      
Senior Notes [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount   750,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember		                                        
Georgia Power [Member]                                            
Financing (Textual) [Abstract]                                            
Other Long-term Debt   2,883,000,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 1,680,000,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Senior notes, current   1,050,000,000us-gaap_SeniorNotesCurrent
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 0us-gaap_SeniorNotesCurrent
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Long term debt and capital lease obligations, maturities in 2014   1,200,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearOne
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Long term debt and capital lease obligations, maturities in 2015   710,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearTwo
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Long term debt and capital lease obligations, maturities in 2016   457,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearThree
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Long Term Debt and Capital Lease Obligation Maturities Repayments in Year Four   257,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearFour
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Long term debt and capital lease obligations, maturities in 2018   508,000,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearFive
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months   1,050,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 1,050,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Long-term debt maturities, 2016   250,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 250,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Long-term debt maturities, 2016   450,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 450,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Long-term Debt, Maturities, Repayments of Principal in Year Five   500,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 500,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Long-term Debt, Maturities, Repayments of Principal in Year Four   250,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 250,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Repayments of Pollution Control Bond   37,000,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 298,000,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 284,000,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                    
Bank Loans     400,000,000us-gaap_BankLoans
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Bank loans, period of extension           4 months                                
Aggregate Principal Amount Of Floating Rate Bank Loan           400,000,000so_AggregatePrincipalAmountOfFloatingRateBankLoan
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                
Number Of Bank Loans           3so_NumberOfBankLoans
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                
Ratio of indebtedness to capitalization, debt covenant, required   65.00%so_RatioOfIndebtednessToCapitalizationCovenant
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Percent Of Eligible Project Costs To Be Reimbursed         70.00%so_PercentOfEligibleProjectCostsToBeReimbursed
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                  
Eligible Project Costs To Be Reimbursed         3,460,000,000so_EligibleProjectCostsToBeReimbursed
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                  
Debt Instrument, Basis Spread on Variable Rate         0.375%us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                  
Payments of Debt Issuance Costs         66,000,000us-gaap_PaymentsOfDebtIssuanceCosts
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                  
Senior Notes outstanding     6,900,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Line of Credit Facility, Current Borrowing Capacity         1,000,000,000us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		             200,000,000us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                    
Amortization Period For Line Of Credit Facility         5 years                                  
Pollution control revenue bonds, outstanding   1,600,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 1,700,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Derivative, Notional Amount   1,600,000,000invest_DerivativeNotionalAmount
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Capitalized lease obligations   40,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 45,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment   11,222,000,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 10,970,000,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Unused credit with banks   1,736,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support   865,000,000so_AmountOfVariableRatePollutionControlRevenueBondsOutstandingRequiringLiquiditySupport
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Pollution Control Revenue Bonds Required To Be Remarketed   118,000,000so_PollutionControlRevenueBondsRequiredToBeRemarketed
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Long-term Pollution Control Bond, Current   98,000,000us-gaap_LongtermPollutionControlBondCurrent
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 0us-gaap_LongtermPollutionControlBondCurrent
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Redemption price of redeemable preferred stock, as a percent of liquidation amount   100.00%so_TemporaryEquityRedemptionPricePercentOfLiquidationAmountOfPreferredStock
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Short-term Debt   156,000,000us-gaap_ShortTermBorrowings
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		 1,047,000,000us-gaap_ShortTermBorrowings
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                      
Commitment fee percentage (less than 1/4 of 1%)   0.25%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Georgia Power [Member] | Corporate, Non-Segment [Member]                                            
Financing (Textual) [Abstract]                                            
Capitalized lease obligations   61,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_CorporateNonSegmentMember		 61,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_CorporateNonSegmentMember		                                      
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment   21,000,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_CorporateNonSegmentMember		 16,000,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_CorporateNonSegmentMember		                                      
Georgia Power [Member] | FIrst Series 2009 [Member]                                            
Financing (Textual) [Abstract]                                            
Repayment Aggregate Principal Amount Of Floating Rate Bank Loan                         40,000,000so_RepaymentAggregatePrincipalAmountOfFloatingRateBankLoan
/ us-gaap_DebtInstrumentAxis
= so_FIrstSeries2009Member
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                  
Georgia Power [Member] | Redemption In Connection With Unit Retirement [Member]                                            
Financing (Textual) [Abstract]                                            
Long-term Pollution Control Bond, Current   98,000,000us-gaap_LongtermPollutionControlBondCurrent
/ us-gaap_DebtInstrumentAxis
= so_RedemptionInConnectionWithUnitRetirementMember
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Georgia Power [Member] | Line of Credit [Member] | Debt Due 2029 [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount         500,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= so_DebtDueTwoThousandTwentyNineMember
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember		                                  
Fixed stated interest rate of debt obligation         3.488%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= so_DebtDueTwoThousandTwentyNineMember
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember		                                  
Georgia Power [Member] | Line of Credit [Member] | Debt Due Two Thousand Forty Four [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount         500,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= so_DebtDueTwoThousandFortyFourMember
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember		                                  
Fixed stated interest rate of debt obligation         3.86%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= so_DebtDueTwoThousandFortyFourMember
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember		             3.002%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= so_DebtDueTwoThousandFortyFourMember
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_LineOfCreditMember		                    
Georgia Power [Member] | Capital Lease Obligations [Member]                                            
Financing (Textual) [Abstract]                                            
Fixed stated interest rate of debt obligation   7.90%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_CapitalLeaseObligationsMember		 7.90%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_CapitalLeaseObligationsMember		                                      
Georgia Power [Member] | Secured Debt [Member]                                            
Financing (Textual) [Abstract]                                            
Long-term Debt   1,200,000,000us-gaap_LongTermDebt
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SecuredDebtMember		 45,000,000us-gaap_LongTermDebt
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SecuredDebtMember		                                      
Georgia Power [Member] | Plant Vogtle Units 3 And 4 [Member]                                            
Financing (Textual) [Abstract]                                            
Jointly Owned Utility Plant, Proportionate Ownership Share         45.70%us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare
/ us-gaap_JointlyOwnedUtilityPlantAxis
= so_PlantVogtleUnits3And4Member
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                  
Georgia Power [Member] | Vogtle Units Three and Four [Member]                                            
Financing (Textual) [Abstract]                                            
Jointly Owned Utility Plant, Proportionate Ownership Share   45.70%us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare
/ us-gaap_JointlyOwnedUtilityPlantAxis
= so_VogtleUnitsThreeAndFourMember
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember		                                        
Subsidiaries [Member]                                            
Financing (Textual) [Abstract]                                            
Capitalized lease obligations   34,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember		 30,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember		                                      
Subsidiaries [Member] | Capital Lease Obligations [Member] | Minimum [Member]                                            
Financing (Textual) [Abstract]                                            
Fixed stated interest rate of debt obligation   1.40%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_CapitalLeaseObligationsMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember		                                        
Subsidiaries [Member] | Capital Lease Obligations [Member] | Maximum [Member]                                            
Financing (Textual) [Abstract]                                            
Fixed stated interest rate of debt obligation   3.20%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= us-gaap_SubsidiariesMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_CapitalLeaseObligationsMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember		                                        
Southern Power and Traditional Operating Companies [Member] | Senior Notes [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount   600,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember
/ dei_LegalEntityAxis
= so_SouthernPowerAndTraditionalOperatingCompaniesMember		                                        
Gulf Power [Member]                                            
Financing (Textual) [Abstract]                                            
Other Long-term Debt   308,955,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_GulfPowerMember		 295,955,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                      
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months   0us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
/ dei_LegalEntityAxis
= so_GulfPowerMember		 75,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                      
Long-term debt maturities, 2016   110,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ dei_LegalEntityAxis
= so_GulfPowerMember		 110,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                      
Long-term Debt, Maturities, Repayments of Principal in Year Four   85,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
/ dei_LegalEntityAxis
= so_GulfPowerMember		 85,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                      
Repayments of Pollution Control Bond   29,075,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_GulfPowerMember		 76,000,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_GulfPowerMember		 13,000,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                    
Ratio of indebtedness to capitalization, debt covenant, required   65.00%so_RatioOfIndebtednessToCapitalizationCovenant
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Line of Credit Facility, Amount Available to Support Variable Rate Pollution Control Revenue Bonds   69,000,000so_LineOfCreditFacilityAmountAvailableToSupportVariableRatePollutionControlRevenueBonds
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Senior Notes outstanding   1,070,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= so_GulfPowerMember		 945,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                      
Line of Credit Facility, Current Borrowing Capacity   275,000,000us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Secured Debt   41,000,000us-gaap_SecuredDebt
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Pollution control revenue bonds, outstanding   309,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_GulfPowerMember		 296,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                      
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment   1,295,714,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_GulfPowerMember		 1,211,336,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                      
Unused credit with banks   275,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Pollution Control Revenue Bonds Required To Be Remarketed   78,000,000so_PollutionControlRevenueBondsRequiredToBeRemarketed
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Redemption price of redeemable preferred stock, as a percent of liquidation amount   100.00%so_TemporaryEquityRedemptionPricePercentOfLiquidationAmountOfPreferredStock
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Common Stock, Shares, Issued             500,000us-gaap_CommonStockSharesIssued
/ dei_LegalEntityAxis
= so_GulfPowerMember		                              
Proceeds from Issuance of Common Stock   50,000,000us-gaap_ProceedsFromIssuanceOfCommonStock
/ dei_LegalEntityAxis
= so_GulfPowerMember		 40,000,000us-gaap_ProceedsFromIssuanceOfCommonStock
/ dei_LegalEntityAxis
= so_GulfPowerMember		 40,000,000us-gaap_ProceedsFromIssuanceOfCommonStock
/ dei_LegalEntityAxis
= so_GulfPowerMember		     50,000,000us-gaap_ProceedsFromIssuanceOfCommonStock
/ dei_LegalEntityAxis
= so_GulfPowerMember		                              
Number of Issuance Pollution Control Revenue Bonds   2so_NumberofIssuancePollutionControlRevenueBonds
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Short-term Debt   109,977,000us-gaap_ShortTermBorrowings
/ dei_LegalEntityAxis
= so_GulfPowerMember		 135,878,000us-gaap_ShortTermBorrowings
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                      
Commitment fee percentage (less than 1/4 of 1%)   0.25%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                        
Gulf Power [Member] | Subsequent Event [Member]                                            
Financing (Textual) [Abstract]                                            
Common Stock, Shares, Issued               200,000us-gaap_CommonStockSharesIssued
/ dei_LegalEntityAxis
= so_GulfPowerMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember		                            
Proceeds from Issuance of Common Stock               20,000,000us-gaap_ProceedsFromIssuanceOfCommonStock
/ dei_LegalEntityAxis
= so_GulfPowerMember
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember		                            
Gulf Power [Member] | Minimum [Member]                                            
Financing (Textual) [Abstract]                                            
Redeemable preferred stock, redemption period   5 years                                        
Gulf Power [Member] | Maximum [Member]                                            
Financing (Textual) [Abstract]                                            
Redeemable preferred stock, redemption period   10 years                                        
Gulf Power [Member] | Plant Daniel [Member]                                            
Financing (Textual) [Abstract]                                            
Pollution control revenue bonds, outstanding   41,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_GulfPowerMember
/ us-gaap_PublicUtilityAxis
= so_PlantDanielMember		                                        
Gulf Power [Member] | Series Two Thousand Twelve [Member]                                            
Financing (Textual) [Abstract]                                            
Pollution control revenue bonds, outstanding 13,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ us-gaap_DebtInstrumentAxis
= so_SeriesTwoThousandTwelveMember
/ dei_LegalEntityAxis
= so_GulfPowerMember		                                          
Gulf Power [Member] | First Series Two Thousand Fourteen [Member]                                            
Financing (Textual) [Abstract]                                            
Pollution control revenue bonds, outstanding                           29,075,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ us-gaap_DebtInstrumentAxis
= so_FirstSeriesTwoThousandFourteenMember
/ dei_LegalEntityAxis
= so_GulfPowerMember		                
Gulf Power [Member] | Series Two Thousand Three [Member]                                            
Financing (Textual) [Abstract]                                            
Redemption Amount of Principal                           29,075,000so_RedemptionAmountOfPrincipal
/ us-gaap_DebtInstrumentAxis
= so_SeriesTwoThousandThreeMember
/ dei_LegalEntityAxis
= so_GulfPowerMember		                
Gulf Power [Member] | Series Two Thousand Fourteen A [Member] | Senior Notes [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount                             200,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember
/ us-gaap_InvestmentTypeAxis
= so_SeriesTwoThousandFourteenAMember
/ dei_LegalEntityAxis
= so_GulfPowerMember		              
Fixed stated interest rate of debt obligation                             4.55%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember
/ us-gaap_InvestmentTypeAxis
= so_SeriesTwoThousandFourteenAMember
/ dei_LegalEntityAxis
= so_GulfPowerMember		              
Gulf Power [Member] | Series K [Member] | Senior Notes [Member]                                            
Financing (Textual) [Abstract]                                            
Redemption Amount of Principal Notes                             75,000,000so_RedemptionAmountOfPrincipalNotes
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember
/ us-gaap_InvestmentTypeAxis
= so_SeriesKMember
/ dei_LegalEntityAxis
= so_GulfPowerMember		              
Fixed stated interest rate of debt obligation                             4.90%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember
/ us-gaap_InvestmentTypeAxis
= so_SeriesKMember
/ dei_LegalEntityAxis
= so_GulfPowerMember		              
Southern Company [Member]                                            
Financing (Textual) [Abstract]                                            
Senior Notes outstanding   2,200,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember		 1,800,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember		                                      
Unused credit with banks   1,000,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ dei_LegalEntityAxis
= us-gaap_ParentCompanyMember		                                        
Southern Power [Member]                                            
Financing (Textual) [Abstract]                                            
Prepayment of debt   9,500,000us-gaap_EarlyRepaymentOfSeniorDebt
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Other Long-term Debt   18,800,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_SouthernPowerMember		 17,800,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                      
Senior notes, current   525,000,000us-gaap_SeniorNotesCurrent
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Other Long-term Debt   300,000us-gaap_OtherLongTermDebtCurrent
/ dei_LegalEntityAxis
= so_SouthernPowerMember		 600,000us-gaap_OtherLongTermDebtCurrent
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                      
Ratio of indebtedness to capitalization, debt covenant, required   65.00%so_RatioOfIndebtednessToCapitalizationCovenant
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Line of Credit Facility, Amount Outstanding     0us-gaap_LineOfCredit
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                      
Senior Notes outstanding   1,600,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Line of Credit Facility, Current Borrowing Capacity                               500,000,000us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
/ dei_LegalEntityAxis
= so_SouthernPowerMember		            
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment   1,034,610,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_SouthernPowerMember		 871,963,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                      
Unused credit with banks   488,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Short-term Debt   194,917,000us-gaap_ShortTermBorrowings
/ dei_LegalEntityAxis
= so_SouthernPowerMember		 0us-gaap_ShortTermBorrowings
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                      
Commitment fee percentage (less than 1/4 of 1%)   0.25%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Projected cash flows from fixed price PPAs, as a percentage of total projected cash flows for the next 12 months   80.00%so_ProjectedCashFlowsFromFixedPricedCapacityPpasAsPercentageOfTotalProjectedCashFlowsForNextTwelveMonths
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Ratio of indebtedness to capitalization, actual, end of period   60.00%so_RatioOfIndebtednessToCapitalizationEndOfPeriod
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Southern Power [Member] | Series 2013A [Member] | Senior Notes [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount   300,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember
/ us-gaap_InvestmentTypeAxis
= so_SeriesTwoThousandThirteenAMember
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Fixed stated interest rate of debt obligation   5.25%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember
/ us-gaap_InvestmentTypeAxis
= so_SeriesTwoThousandThirteenAMember
/ dei_LegalEntityAxis
= so_SouthernPowerMember		                                        
Mississippi Power [Member]                                            
Financing (Textual) [Abstract]                                            
Promissory Note   220,000,000so_PromissoryNote
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Other Long-term Debt   352,695,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 352,695,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Long term debt and capital lease obligations, maturities in 2014   777,700,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearOne
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Long term debt and capital lease obligations, maturities in 2015   302,800,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearTwo
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Long term debt and capital lease obligations, maturities in 2016   37,900,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearThree
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Long Term Debt and Capital Lease Obligation Maturities Repayments in Year Four   3,100,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearFour
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Long term debt and capital lease obligations, maturities in 2018   128,200,000so_LongTermDebtandCapitalLeaseObligationMaturitiesRepaymentsinYearFive
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Long-term debt maturities, 2016   300,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 300,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Long-term debt maturities, 2016   35,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 35,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Long-term Debt, Maturities, Repayments of Principal in Year Four   125,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 125,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Description of variable rate basis   one-month         one-month                              
Bank Loans   775,000,000us-gaap_BankLoans
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 525,000,000us-gaap_BankLoans
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Bank loans, period of extension             18 months   19 months                          
Aggregate Principal Amount Of Floating Rate Bank Loan             250,000,000so_AggregatePrincipalAmountOfFloatingRateBankLoan
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                              
Bank loans outstanding   775,000,000us-gaap_LoansPayableToBank
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 525,000,000us-gaap_LoansPayableToBank
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Ratio of indebtedness to capitalization, debt covenant, required   65.00%so_RatioOfIndebtednessToCapitalizationCovenant
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Senior Notes outstanding   1,100,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 1,100,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Pollution control revenue bonds, outstanding   82,700,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 82,700,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Revenue bond obligations face value                     270,000,000so_RevenueBondObligationsFaceValue
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                      
Fixed stated interest rate of debt obligation   10.134%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 9.932%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 9.967%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_MississippiPowerMember		             7.13%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                      
Other revenue bond obligation   50,000,000so_RevenueBonds
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 50,000,000so_RevenueBonds
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Taxable Revenue Bonds     11,300,000so_TaxableRevenueBonds
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Period Of Nitrogen Supply Agreement                   20 years                        
Capitalized lease obligations   79,679,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 82,217,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Capital leases, due 2014   6,500,000us-gaap_CapitalLeasesFutureMinimumPaymentsDueCurrent
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Capital leases, due 2015   6,500,000us-gaap_CapitalLeasesFutureMinimumPaymentsDueInTwoYears
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Capital leases, due 2016   6,500,000us-gaap_CapitalLeasesFutureMinimumPaymentsDueInThreeYears
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Capital leases, due 2017   6,500,000us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFourYears
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Capital leases, due 2018   6,500,000us-gaap_CapitalLeasesFutureMinimumPaymentsDueInFiveYears
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Capital leases, due 2019 and thereafter   6,500,000us-gaap_CapitalLeasesFutureMinimumPaymentsDueThereafter
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Deposit Liability, Current                                       150,000,000us-gaap_DepositLiabilityCurrent
/ dei_LegalEntityAxis
= so_MississippiPowerMember		    
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment   1,172,715,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 1,095,352,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Deposit Received       150,000,000so_DepositReceived
/ dei_LegalEntityAxis
= so_MississippiPowerMember		     75,000,000so_DepositReceived
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                   50,000,000so_DepositReceived
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 50,000,000so_DepositReceived
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 75,000,000so_DepositReceived
/ dei_LegalEntityAxis
= so_MississippiPowerMember		      
Maximum Period to Refund Deposit upon Termination of Asset Purchase Agreement   15 days                                        
Unused credit with banks   300,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support   40,100,000so_AmountOfVariableRatePollutionControlRevenueBondsOutstandingRequiringLiquiditySupport
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Long-term Pollution Control Bond, Current   0us-gaap_LongtermPollutionControlBondCurrent
/ dei_LegalEntityAxis
= so_MississippiPowerMember		 11,300,000us-gaap_LongtermPollutionControlBondCurrent
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                      
Redemption price of redeemable preferred stock, as a percent of liquidation amount   100.00%so_TemporaryEquityRedemptionPricePercentOfLiquidationAmountOfPreferredStock
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Commitment fee percentage (less than 1/4 of 1%)   0.25%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                        
Mississippi Power [Member] | Kemper IGCC [Member]                                            
Financing (Textual) [Abstract]                                            
Capitalized lease obligations                   80,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_PublicUtilityAxis
= so_KemperIgccMember		                        
Mississippi Power [Member] | Plant Daniel Units 3 and 4 [Member]                                            
Financing (Textual) [Abstract]                                            
Revenue bond obligations face value       270,000,000so_RevenueBondObligationsFaceValue
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_PublicUtilityAxis
= so_PlantDanielUnitsThreeAndFourMember		                                    
Significant Acquisitions and Disposals, Acquisition Costs, Assumption of Debt, at Fair Value       346,100,000so_SignificantAcquisitionsAndDisposalsAcquisitionCostsAssumptionOfDebtAtFairValue
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_PublicUtilityAxis
= so_PlantDanielUnitsThreeAndFourMember		                                    
Fair value adjustment at date of purchase       76,100,000so_SignificantAcquisitionsAndDisposalsAcquisitionCostsAssumptionOfDebtFairValueAdjustment
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_PublicUtilityAxis
= so_PlantDanielUnitsThreeAndFourMember		                                    
Mississippi Power [Member] | Series 1999A [Member]                                            
Financing (Textual) [Abstract]                                            
Fixed stated interest rate of debt obligation       7.13%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ us-gaap_DebtInstrumentAxis
= so_Series1999AMember
/ dei_LegalEntityAxis
= so_MississippiPowerMember		                                    
Mississippi Power [Member] | Revenue Bonds [Member] | Mississippi Business Finance Corporation Taxable Revenue Bonds, Series 2012A [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount   22,870,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= so_MississippiBusinessFinanceCorporationTaxableRevenueBondsSeriesTwoThousandThirteenAMember
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_RevenueBondsMember		             12,300,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= so_MississippiBusinessFinanceCorporationTaxableRevenueBondsSeriesTwoThousandThirteenAMember
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_RevenueBondsMember		                       10,500,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= so_MississippiBusinessFinanceCorporationTaxableRevenueBondsSeriesTwoThousandThirteenAMember
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_RevenueBondsMember		  
Debt Instrument, Face Amount, Authorized to Issue                                           33,750,000.00so_DebtInstrumentFaceAmountAuthorizedToIssue
/ us-gaap_DebtInstrumentAxis
= so_MississippiBusinessFinanceCorporationTaxableRevenueBondsSeriesTwoThousandThirteenAMember
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_RevenueBondsMember
Mississippi Power [Member] | Revenue Bonds [Member] | Mississippi Business Finance Corporation Taxable Revenue Bonds, Series 2012B [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount   11,250,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= so_MississippiBusinessFinanceCorporationTaxableRevenueBondsSeriesTwoThousandThirteenBMember
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_RevenueBondsMember		                                       11,250,000.00us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= so_MississippiBusinessFinanceCorporationTaxableRevenueBondsSeriesTwoThousandThirteenBMember
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_RevenueBondsMember
Debt Instrument, Face Amount, Authorized to Issue                                           11,250,000.00so_DebtInstrumentFaceAmountAuthorizedToIssue
/ us-gaap_DebtInstrumentAxis
= so_MississippiBusinessFinanceCorporationTaxableRevenueBondsSeriesTwoThousandThirteenBMember
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_RevenueBondsMember
Mississippi Power [Member] | Capital Lease Obligations [Member]                                            
Financing (Textual) [Abstract]                                            
Fixed stated interest rate of debt obligation                   4.90%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_MississippiPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_CapitalLeaseObligationsMember		                        
Southern Company And Subsidiaries [Member] | Senior Notes [Member]                                            
Financing (Textual) [Abstract]                                            
Debt Instrument, Face Amount   1,400,000,000us-gaap_DebtInstrumentFaceAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_SeniorNotesMember
/ dei_LegalEntityAxis
= so_SouthernCompanyAndSubsidiariesMember		                                        
Alabama Power and Gulf Power [Member] | Secured Debt [Member]                                            
Financing (Textual) [Abstract]                                            
Pollution control revenue bonds, outstanding   41,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ us-gaap_DebtInstrumentAxis
= us-gaap_SecuredDebtMember
/ dei_LegalEntityAxis
= so_AlabamaPowerAndGulfPowerMember		                                        
Traditional Operating Companies [Member]                                            
Financing (Textual) [Abstract]                                            
Pollution control revenue bonds, outstanding   3,200,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_TraditionalOperatingCompaniesMember		 3,200,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_TraditionalOperatingCompaniesMember		                                      
Alabama Power [Member]                                            
Financing (Textual) [Abstract]                                            
Proceeds from issuance of junior subordinated notes   206,000,000us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrustCurrent
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 206,000,000us-gaap_JuniorSubordinatedDebentureOwedToUnconsolidatedSubsidiaryTrustCurrent
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Senior Notes And Pollution Control Revenue Bonds, Current   454,000,000so_SeniorNotesAndPollutionControlRevenueBondsCurrent
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Other Long-term Debt   1,151,000,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 1,151,000,000us-gaap_OtherLongTermDebt
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months   400,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 400,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Long-term debt maturities, 2016   200,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 200,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Long-term debt maturities, 2016   525,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 525,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Long-term Debt, Maturities, Repayments of Principal in Year Five   200,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 200,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Issuance Of Pollution Control Bond   254,000,000so_IssuanceOfPollutionControlBond
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Repayments of Pollution Control Bond   254,000,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 0us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 1,000,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                    
Ratio of indebtedness to capitalization, debt covenant, required   65.00%so_RatioOfIndebtednessToCapitalizationCovenant
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Jointly Owned Utility Plant, Proportionate Ownership Share   14.00%us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Pollution control revenue bonds, outstanding   1,200,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 1,200,000,000us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Derivative, Notional Amount                                 200,000,000invest_DerivativeNotionalAmount
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		          
Capitalized lease obligations   5,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 5,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment   8,522,000,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 8,114,000,000us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Unused credit with banks   1,308,000,000us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Amount of Variable Rate Pollution Control Revenue Bonds Outstanding Requiring Liquidity Support   784,000,000so_AmountOfVariableRatePollutionControlRevenueBondsOutstandingRequiringLiquiditySupport
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Pollution Control Revenue Bonds Required To Be Remarketed   280,000,000so_PollutionControlRevenueBondsRequiredToBeRemarketed
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Short-term debt outstanding, regulatory approved maximum   2,000,000,000so_ShortTermDebtOutstandingRegulatoryApprovedMaximum
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Commitment fee percentage (less than 1/4 of 1%)   0.10%us-gaap_LineOfCreditFacilityCommitmentFeePercentage
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Alabama Power [Member] | Natural Gas Pipeline [Member]                                            
Financing (Textual) [Abstract]                                            
Capitalized lease obligations   5,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_PublicUtilityAxis
= so_NaturalGasPipelineMember		 5,000,000us-gaap_CapitalLeaseObligations
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_PublicUtilityAxis
= so_NaturalGasPipelineMember		                                      
Alabama Power [Member] | Trust Preferred Securities Subject to Mandatory Redemption [Member]                                            
Financing (Textual) [Abstract]                                            
Preferred securities, outstanding   200,000,000us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsMaximumAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		 200,000,000us-gaap_SharesSubjectToMandatoryRedemptionSettlementTermsMaximumAmount
/ us-gaap_DebtInstrumentAxis
= us-gaap_TrustPreferredSecuritiesSubjectToMandatoryRedemptionMember
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                      
Alabama Power [Member] | Senior Notes And Pollution Control Bond [Member]                                            
Financing (Textual) [Abstract]                                            
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months   454,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths
/ us-gaap_DebtInstrumentAxis
= so_SeniorNotesAndPollutionControlBondMember
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Long-term debt maturities, 2016   200,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo
/ us-gaap_DebtInstrumentAxis
= so_SeniorNotesAndPollutionControlBondMember
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Long-term debt maturities, 2016   561,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
/ us-gaap_DebtInstrumentAxis
= so_SeniorNotesAndPollutionControlBondMember
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Long-term Debt, Maturities, Repayments of Principal in Year Five   200,000,000us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive
/ us-gaap_DebtInstrumentAxis
= so_SeniorNotesAndPollutionControlBondMember
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Long-term Debt, Maturities, Repayments of Principal in Year Four   0us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour
/ us-gaap_DebtInstrumentAxis
= so_SeniorNotesAndPollutionControlBondMember
/ dei_LegalEntityAxis
= so_AlabamaPowerMember		                                        
Alabama Power [Member] | Series 2014A [Member]                                            
Financing (Textual) [Abstract]                                            
Fixed stated interest rate of debt obligation                                         4.15%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_Series2014AMember		  
Alabama Power [Member] | Series 2014DD [Member]                                            
Financing (Textual) [Abstract]                                            
Fixed stated interest rate of debt obligation   5.65%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_SeriesDDMember		                                        
Alabama Power [Member] | Multiple Bonds [Member]                                            
Financing (Textual) [Abstract]                                            
Repayments of Pollution Control Bond   254,000,000us-gaap_RepaymentsOfPollutionControlBond
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= so_MultipleBondsMember		                                        
Alabama Power [Member] | Capital Lease Obligations [Member]                                            
Financing (Textual) [Abstract]                                            
Fixed stated interest rate of debt obligation   6.90%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_CapitalLeaseObligationsMember		 6.90%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_CapitalLeaseObligationsMember		                                      
Alabama Power [Member] | Unsecured Debt [Member]                                            
Financing (Textual) [Abstract]                                            
Redemption Amount of Principal Notes   250,000,000so_RedemptionAmountOfPrincipalNotes
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember		                                     400,000,000so_RedemptionAmountOfPrincipalNotes
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember		  
Senior Notes outstanding   5,300,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember		 4,900,000,000us-gaap_SeniorNotes
/ dei_LegalEntityAxis
= so_AlabamaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_UnsecuredDebtMember		                                      
Notes due April 30, 2033 [Member] | Southern Power [Member]                                            
Financing (Textual) [Abstract]                                            
Promissory Note   800,000so_PromissoryNote
/ dei_LegalEntityAxis
= so_SouthernPowerMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= so_DueAprilThirtiethTwoThousandThirtyThreeMember		                                        
Notes due September 30, 2032 [Member] | Southern Power [Member]                                            
Financing (Textual) [Abstract]                                            
Promissory Note   100,000so_PromissoryNote
/ dei_LegalEntityAxis
= so_SouthernPowerMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= so_DebtDueJuneFifteenthTwoThousandThirtyTwoMember		                                        
Debt Due April Thirtieth Two Thousand Thirty Four [Member] | Southern Power [Member]                                            
Financing (Textual) [Abstract]                                            
Promissory Note   3,900,000so_PromissoryNote
/ dei_LegalEntityAxis
= so_SouthernPowerMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= so_DebtDueAprilThirtiethTwoThousandThirtyFourMember		                                        
Debt Due May Thirty First Two Thousand Thirty Four [Member] | Southern Power [Member]                                            
Financing (Textual) [Abstract]                                            
Promissory Note   5,400,000so_PromissoryNote
/ dei_LegalEntityAxis
= so_SouthernPowerMember
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= so_DebtDueMayThirtyFirstTwoThousandThirtyFourMember		                                        
Capital Lease Obligations [Member] | Georgia Power [Member] | Secured Debt [Member]                                            
Financing (Textual) [Abstract]                                            
Long-term Debt   $ 1,200,000,000us-gaap_LongTermDebt
/ us-gaap_GuaranteeObligationsByNatureAxis
= us-gaap_CapitalLeaseObligationsMember
/ dei_LegalEntityAxis
= so_GeorgiaPowerMember
/ us-gaap_LongtermDebtTypeAxis
= us-gaap_SecuredDebtMember