2.4.0.82408403 - Disclosure - Derivatives - Schedule of Derivatives and Gains (Losses) (Details)truefalseIn Millions, unless otherwise specifiedfalse1false USDfalsefalseD2013Q2YTD_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaap_FairValueHedgingMemberhttp://www.sec.gov/CIK0000092122duration2013-01-01T00:00:002013-06-30T00:00:00numberStandardhttp://www.xbrl.org/2003/instancepurexbrli0usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170$1true 4us-gaap_NotionalAmountOfDerivativesAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Notional amount of interest rate derivatives2false 5invest_DerivativeNotionalAmountinvest_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse350000000350USD$falsetruefalsexbrli:monetaryItemTypemonetaryAggregate notional amount specified by the derivative(s). Expressed as an absolute value.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B false2Notional Amount3false 5us-gaap_DerivativeBasisSpreadOnVariableRateus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.01960.0196[1]falsefalsefalsenum:percentItemTypepureThe percentage points added to the reference rate to compute the variable rate on the interest rate derivative.No definition available.false0Interest Rate Paid, basis spread on LIBOR4false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false USDtruefalseD2013Q2YTD_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_us-gaap_FairValueHedgingMemberhttp://www.sec.gov/CIK0000092122duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseFair Value Hedging [Member]us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_FairValueHedgingMemberus-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxisexplicitMembernumberStandardhttp://www.xbrl.org/2003/instancepurexbrli0usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170$nanafalse0Fair Value Hedging [Member]5true 4us-gaap_NotionalAmountOfDerivativesAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Notional amount of interest rate derivatives6false 5us-gaap_DerivativeFixedInterestRateus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.04150.0415falsefalsefalsenum:percentItemTypepureFixed interest rate related to the interest rate derivative.No definition available.false0Interest Rate Received7false 5so_NotionalAmountOfInterestRateDerivativesInterestRatePaidso_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse003-month LIBOR  + 1.96%[1]falsefalsefalsexbrli:stringItemTypestringNotional amount of interest rate derivatives, interest rate paid.No definition available.false0Interest Rate Paid8false 5us-gaap_DerivativeMaturityDatesus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse002014-05-01falsefalsetruexbrli:dateItemTypedateDate the derivative contract matures, in CCYY-MM-DD format.No definition available.false0Hedge Maturity Date9false 5so_FairValueGainLossso_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse60000006USD$falsetruefalsexbrli:monetaryItemTypemonetaryFair value gain (Loss).No definition available.false2Fair Value Gain (Loss) June 30, 201310false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse3false truefalseI2013Q2_us-gaap_DerivativeByNatureAxis_us-gaap_PublicUtilitiesInventoryNaturalGasMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGas [Member]us-gaap_DerivativeByNatureAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PublicUtilitiesInventoryNaturalGasMemberus-gaap_DerivativeByNatureAxisexplicitMembermmbtuStandardhttp://www.xbrl.org/2009/utrMMBTUutreg0nanafalse0Gas [Member]11true 4so_EnergyRelatedDerivativeContractsForRegistrantsAbstractso_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Energy-related derivative contracts12false 5so_NetQuantityPurchaseOfDerivativesNotDesignatedAsHedgesso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse270000000270000000falsefalsefalsenum:energyItemTypedecimalNet quantity purchase of derivatives not designated as hedges.No definition available.false256Net Purchased mmBtu13false 5so_LongestHedgeDateso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse002017falsefalsefalsexbrli:gYearItemTypepositiveintegerLongest hedge date.No definition available.false0Longest Hedge Date14false 5so_LongestNonHedgeDateso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse002017falsefalsefalsexbrli:gYearItemTypepositiveintegerLongest non-hedge date.No definition available.false0Longest Non-Hedge Date15false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse4false truefalseI2013Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_DerivativeByNatureAxis_us-gaap_PublicUtilitiesInventoryNaturalGasMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGas [Member]us-gaap_DerivativeByNatureAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PublicUtilitiesInventoryNaturalGasMemberus-gaap_DerivativeByNatureAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMembermmbtuStandardhttp://www.xbrl.org/2009/utrMMBTUutreg0nanafalse0Gas [Member] | Alabama Power [Member]16true 4so_EnergyRelatedDerivativeContractsForRegistrantsAbstractso_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Energy-related derivative contracts17false 5so_NetQuantityPurchaseOfDerivativesNotDesignatedAsHedgesso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse6800000068000000falsefalsefalsenum:energyItemTypedecimalNet quantity purchase of derivatives not designated as hedges.No definition available.false256Net Purchased mmBtu18false 5so_LongestHedgeDateso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse002017falsefalsefalsexbrli:gYearItemTypepositiveintegerLongest hedge date.No definition available.false0Longest Hedge Date19false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse5false truefalseI2013Q2_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_DerivativeByNatureAxis_us-gaap_PublicUtilitiesInventoryNaturalGasMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGas [Member]us-gaap_DerivativeByNatureAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PublicUtilitiesInventoryNaturalGasMemberus-gaap_DerivativeByNatureAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMembermmbtuStandardhttp://www.xbrl.org/2009/utrMMBTUutreg0nanafalse0Gas [Member] | Georgia Power [Member]20true 4so_EnergyRelatedDerivativeContractsForRegistrantsAbstractso_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Energy-related derivative contracts21false 5so_NetQuantityPurchaseOfDerivativesNotDesignatedAsHedgesso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse7800000078000000falsefalsefalsenum:energyItemTypedecimalNet quantity purchase of derivatives not designated as hedges.No definition available.false256Net Purchased mmBtu22false 5so_LongestHedgeDateso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse002017falsefalsefalsexbrli:gYearItemTypepositiveintegerLongest hedge date.No definition available.false0Longest Hedge Date23false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse6false truefalseI2013Q2_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_DerivativeByNatureAxis_us-gaap_PublicUtilitiesInventoryNaturalGasMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGas [Member]us-gaap_DerivativeByNatureAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PublicUtilitiesInventoryNaturalGasMemberus-gaap_DerivativeByNatureAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMembermmbtuStandardhttp://www.xbrl.org/2009/utrMMBTUutreg0nanafalse0Gas [Member] | Gulf Power [Member]24true 4so_EnergyRelatedDerivativeContractsForRegistrantsAbstractso_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Energy-related derivative contracts25false 5so_NetQuantityPurchaseOfDerivativesNotDesignatedAsHedgesso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse7900000079000000falsefalsefalsenum:energyItemTypedecimalNet quantity purchase of derivatives not designated as hedges.No definition available.false256Net Purchased mmBtu26false 5so_LongestHedgeDateso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse002017falsefalsefalsexbrli:gYearItemTypepositiveintegerLongest hedge date.No definition available.false0Longest Hedge Date27false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse7false truefalseI2013Q2_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_DerivativeByNatureAxis_us-gaap_PublicUtilitiesInventoryNaturalGasMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGas [Member]us-gaap_DerivativeByNatureAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PublicUtilitiesInventoryNaturalGasMemberus-gaap_DerivativeByNatureAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMembermmbtuStandardhttp://www.xbrl.org/2009/utrMMBTUutreg0nanafalse0Gas [Member] | Mississippi Power [Member]28true 4so_EnergyRelatedDerivativeContractsForRegistrantsAbstractso_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Energy-related derivative contracts29false 5so_NetQuantityPurchaseOfDerivativesNotDesignatedAsHedgesso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse4300000043000000falsefalsefalsenum:energyItemTypedecimalNet quantity purchase of derivatives not designated as hedges.No definition available.false256Net Purchased mmBtu30false 5so_LongestHedgeDateso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse002017falsefalsefalsexbrli:gYearItemTypepositiveintegerLongest hedge date.No definition available.false0Longest Hedge Date31false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse8false truefalseI2013Q2_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_DerivativeByNatureAxis_us-gaap_PublicUtilitiesInventoryNaturalGasMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseGas [Member]us-gaap_DerivativeByNatureAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_PublicUtilitiesInventoryNaturalGasMemberus-gaap_DerivativeByNatureAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMembermmbtuStandardhttp://www.xbrl.org/2009/utrMMBTUutreg0nanafalse0Gas [Member] | Southern Power [Member]32true 4so_EnergyRelatedDerivativeContractsForRegistrantsAbstractso_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Energy-related derivative contracts33false 5so_NetQuantityPurchaseOfDerivativesNotDesignatedAsHedgesso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse20000002000000falsefalsefalsenum:energyItemTypedecimalNet quantity purchase of derivatives not designated as hedges.No definition available.false256Net Purchased mmBtu34false 5so_LongestNonHedgeDateso_falsenainstantfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse002017falsefalsefalsexbrli:gYearItemTypepositiveintegerLongest non-hedge date.No definition available.false0Longest Non-Hedge Date1(a)Weighted averagefalseDerivatives - Schedule of Derivatives and Gains (Losses) (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://southerncompany.com/role/DerivativesScheduleOfDerivativesAndGainsLossesDetails134