2.4.0.82408406 - Disclosure - Derivatives - Pre-tax Effects of Derivatives Designated as Cash Flow Hedging Instruments (Details)truefalseIn Millions, unless otherwise specifiedfalse1false USDtruefalse$D2013Q2_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDtruefalse$D2012Q2_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2012-04-01T00:00:002012-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$3false USDtruefalse$D2013Q2YTD_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$4false USDtruefalse$D2012Q2YTD_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2012-01-01T00:00:002012-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$5false USDtruefalse$D2013Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$6false USDtruefalse$D2012Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2012-04-01T00:00:002012-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$7false USDtruefalse$D2013Q2YTD_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$8false USDtruefalse$D2012Q2YTD_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2012-01-01T00:00:002012-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$9false USDtruefalse$D2013Q2_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$10false USDtruefalse$D2012Q2_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2012-04-01T00:00:002012-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$11false USDtruefalse$D2013Q2YTD_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$12false USDtruefalse$D2012Q2YTD_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_IncomeStatementLocationAxis_us-gaap_InterestExpenseMemberhttp://www.sec.gov/CIK0000092122duration2012-01-01T00:00:002012-06-30T00:00:00falsefalseInterest Expense [Member]us-gaap_IncomeStatementLocationAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestExpenseMemberus-gaap_IncomeStatementLocationAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$13false USDtruefalse$I2013Q2_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$14false USDtruefalse$I2012Q4_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$15false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$16false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$17false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$18false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$19false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$20false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$21false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$22false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$23false USDtruefalse$I2013Q2_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$24false USDtruefalse$I2012Q4_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$25false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$26false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$27false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$28false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$29false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$30false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$31false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$32false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$33false USDtruefalse$I2013Q2_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$34false USDtruefalse$I2012Q4_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$35false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$36false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$37false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$38false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$39false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$40false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$41false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$42false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryAssetsDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory assets deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryAssetsDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$43false USDtruefalse$I2013Q2_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$44false USDtruefalse$I2012Q4_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$45false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$46false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$47false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$48false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$49false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$50false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$51false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$52false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesCurrentMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities current [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesCurrentMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$53false USDtruefalse$I2013Q2_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$54false USDtruefalse$I2012Q4_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$55false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$56false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$57false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$58false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GeorgiaPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGeorgia Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GeorgiaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$59false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$60false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_GulfPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseGulf Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_GulfPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$61false USDtruefalse$I2013Q2_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$62false USDtruefalse$I2012Q4_dei_LegalEntityAxis_so_MississippiPowerMember_us-gaap_BalanceSheetLocationAxis_so_OtherRegulatoryLiabilitiesDeferredMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_EnergyRelatedDerivativeMemberhttp://www.sec.gov/CIK0000092122instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseEnergy Related Derivative [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_EnergyRelatedDerivativeMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseOther regulatory liabilities deferred [Member]us-gaap_BalanceSheetLocationAxisxbrldihttp://xbrl.org/2006/xbrldiso_OtherRegulatoryLiabilitiesDeferredMemberus-gaap_BalanceSheetLocationAxisexplicitMemberfalsefalseMississippi Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_MississippiPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$63false USDtruefalse$D2013Q2_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$64false USDtruefalse$D2012Q2_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2012-04-01T00:00:002012-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$65false USDtruefalse$D2013Q2YTD_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$66false USDtruefalse$D2012Q2YTD_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2012-01-01T00:00:002012-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$67false USDtruefalse$D2013Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$68false USDtruefalse$D2012Q2_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2012-04-01T00:00:002012-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$69false USDtruefalse$D2013Q2YTD_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$70false USDtruefalse$D2012Q2YTD_dei_LegalEntityAxis_so_AlabamaPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2012-01-01T00:00:002012-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseAlabama Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_AlabamaPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$71false USDtruefalse$D2013Q2_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2013-04-01T00:00:002013-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$72false USDtruefalse$D2012Q2_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2012-04-01T00:00:002012-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$73false USDtruefalse$D2013Q2YTD_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$74false USDtruefalse$D2012Q2YTD_dei_LegalEntityAxis_so_SouthernPowerMember_us-gaap_DerivativeInstrumentRiskAxis_us-gaap_InterestRateContractMemberhttp://www.sec.gov/CIK0000092122duration2012-01-01T00:00:002012-06-30T00:00:00falsefalseInterest rate derivatives [Member]us-gaap_DerivativeInstrumentRiskAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_InterestRateContractMemberus-gaap_DerivativeInstrumentRiskAxisexplicitMemberfalsefalseSouthern Power [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiso_SouthernPowerMemberdei_LegalEntityAxisexplicitMemberusdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_DerivativeInstrumentsGainLossLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16falsefalsefalse00falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalse23falsefalsefalse00falsefalsefalse24falsefalsefalse00falsefalsefalse25falsefalsefalse00falsefalsefalse26falsefalsefalse00falsefalsefalse27falsefalsefalse00falsefalsefalse28falsefalsefalse00falsefalsefalse29falsefalsefalse00falsefalsefalse30falsefalsefalse00falsefalsefalse31falsefalsefalse00falsefalsefalse32falsefalsefalse00falsefalsefalse33falsefalsefalse00falsefalsefalse34falsefalsefalse00falsefalsefalse35falsefalsefalse00falsefalsefalse36falsefalsefalse00falsefalsefalse37falsefalsefalse00falsefalsefalse38falsefalsefalse00falsefalsefalse39falsefalsefalse00falsefalsefalse40falsefalsefalse00falsefalsefalse41falsefalsefalse00falsefalsefalse42falsefalsefalse00falsefalsefalse43falsefalsefalse00falsefalsefalse44falsefalsefalse00falsefalsefalse45falsefalsefalse00falsefalsefalse46falsefalsefalse00falsefalsefalse47falsefalsefalse00falsefalsefalse48falsefalsefalse00falsefalsefalse49falsefalsefalse00falsefalsefalse50falsefalsefalse00falsefalsefalse51falsefalsefalse00falsefalsefalse52falsefalsefalse00falsefalsefalse53falsefalsefalse00falsefalsefalse54falsefalsefalse00falsefalsefalse55falsefalsefalse00falsefalsefalse56falsefalsefalse00falsefalsefalse57falsefalsefalse00falsefalsefalse58falsefalsefalse00falsefalsefalse59falsefalsefalse00falsefalsefalse60falsefalsefalse00falsefalsefalse61falsefalsefalse00falsefalsefalse62falsefalsefalse00falsefalsefalse63falsefalsefalse00falsefalsefalse64falsefalsefalse00falsefalsefalse65falsefalsefalse00falsefalsefalse66falsefalsefalse00falsefalsefalse67falsefalsefalse00falsefalsefalse68falsefalsefalse00falsefalsefalse69falsefalsefalse00falsefalsefalse70falsefalsefalse00falsefalsefalse71falsefalsefalse00falsefalsefalse72falsefalsefalse00falsefalsefalse73falsefalsefalse00falsefalsefalse74falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Derivative Instruments, Gain (Loss) [Line Items]2false 4so_RegulatoryHedgeUnrealizedGainLossso_falsecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13truefalsefalse-74000000-74USD$falsetruefalse14truefalsefalse-86000000-86USD$falsetruefalse15truefalsefalse-11000000-11USD$falsetruefalse16truefalsefalse-13000000-13USD$falsetruefalse17truefalsefalse-29000000-29USD$falsetruefalse18truefalsefalse-34000000-34USD$falsetruefalse19truefalsefalse-21000000-21USD$falsetruefalse20truefalsefalse-23000000-23USD$falsetruefalse21truefalsefalse-13000000-13USD$falsetruefalse22truefalsefalse-16000000-16USD$falsetruefalse23truefalsefalse-54000000-54USD$falsetruefalse24truefalsefalse-74000000-74USD$falsetruefalse25truefalsefalse-10000000-10USD$falsetruefalse26truefalsefalse-14000000-14USD$falsetruefalse27truefalsefalse-21000000-21USD$falsetruefalse28truefalsefalse-30000000-30USD$falsetruefalse29truefalsefalse-14000000-14USD$falsetruefalse30truefalsefalse-17000000-17USD$falsetruefalse31truefalsefalse-9000000-9USD$falsetruefalse32truefalsefalse-13000000-13USD$falsetruefalse33truefalsefalse-34000000-34USD$falsetruefalse34truefalsefalse-35000000-35USD$falsetruefalse35truefalsefalse-5000000-5USD$falsetruefalse36truefalsefalse-4000000-4USD$falsetruefalse37truefalsefalse-12000000-12USD$falsetruefalse38truefalsefalse-15000000-15USD$falsetruefalse39truefalsefalse-11000000-11USD$falsetruefalse40truefalsefalse-10000000-10USD$falsetruefalse41truefalsefalse-6000000-6USD$falsetruefalse42truefalsefalse-6000000-6USD$falsetruefalse43truefalsefalse70000007USD$falsetruefalse44truefalsefalse1000000010USD$falsetruefalse45truefalsefalse20000002USD$falsetruefalse46truefalsefalse20000002USD$falsetruefalse47truefalsefalse20000002USD$falsetruefalse48truefalsefalse60000006USD$falsetruefalse49truefalsefalse20000002USD$falsetruefalse50truefalsefalse10000001USD$falsetruefalse51truefalsefalse10000001USD$falsetruefalse52truefalsefalse10000001USD$falsetruefalse53truefalsefalse70000007USD$falsetruefalse54truefalsefalse1300000013USD$falsetruefalse55truefalsefalse20000002USD$falsetruefalse56truefalsefalse30000003USD$falsetruefalse57truefalsefalse20000002USD$falsetruefalse58truefalsefalse50000005USD$falsetruefalse59truefalsefalse20000002USD$falsetruefalse60truefalsefalse30000003USD$falsetruefalse61truefalsefalse10000001USD$falsetruefalse62truefalsefalse20000002USD$falsetruefalse63falsefalsefalse00falsefalsefalse64falsefalsefalse00falsefalsefalse65falsefalsefalse00falsefalsefalse66falsefalsefalse00falsefalsefalse67falsefalsefalse00falsefalsefalse68falsefalsefalse00falsefalsefalse69falsefalsefalse00falsefalsefalse70falsefalsefalse00falsefalsefalse71falsefalsefalse00falsefalsefalse72falsefalsefalse00falsefalsefalse73falsefalsefalse00falsefalsefalse74falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryRegulatory hedge unrealized gain (loss).No definition available.false2Total energy-related derivative gains (losses)3true 4so_PretaxEffectOfDerivativesDesignatedAsCashFlowHedgingInstrumentsAbstractso_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16falsefalsefalse00falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalse23falsefalsefalse00falsefalsefalse24falsefalsefalse00falsefalsefalse25falsefalsefalse00falsefalsefalse26falsefalsefalse00falsefalsefalse27falsefalsefalse00falsefalsefalse28falsefalsefalse00falsefalsefalse29falsefalsefalse00falsefalsefalse30falsefalsefalse00falsefalsefalse31falsefalsefalse00falsefalsefalse32falsefalsefalse00falsefalsefalse33falsefalsefalse00falsefalsefalse34falsefalsefalse00falsefalsefalse35falsefalsefalse00falsefalsefalse36falsefalsefalse00falsefalsefalse37falsefalsefalse00falsefalsefalse38falsefalsefalse00falsefalsefalse39falsefalsefalse00falsefalsefalse40falsefalsefalse00falsefalsefalse41falsefalsefalse00falsefalsefalse42falsefalsefalse00falsefalsefalse43falsefalsefalse00falsefalsefalse44falsefalsefalse00falsefalsefalse45falsefalsefalse00falsefalsefalse46falsefalsefalse00falsefalsefalse47falsefalsefalse00falsefalsefalse48falsefalsefalse00falsefalsefalse49falsefalsefalse00falsefalsefalse50falsefalsefalse00falsefalsefalse51falsefalsefalse00falsefalsefalse52falsefalsefalse00falsefalsefalse53falsefalsefalse00falsefalsefalse54falsefalsefalse00falsefalsefalse55falsefalsefalse00falsefalsefalse56falsefalsefalse00falsefalsefalse57falsefalsefalse00falsefalsefalse58falsefalsefalse00falsefalsefalse59falsefalsefalse00falsefalsefalse60falsefalsefalse00falsefalsefalse61falsefalsefalse00falsefalsefalse62falsefalsefalse00falsefalsefalse63falsefalsefalse00falsefalsefalse64falsefalsefalse00falsefalsefalse65falsefalsefalse00falsefalsefalse66falsefalsefalse00falsefalsefalse67falsefalsefalse00falsefalsefalse68falsefalsefalse00falsefalsefalse69falsefalsefalse00falsefalsefalse70falsefalsefalse00falsefalsefalse71falsefalsefalse00falsefalsefalse72falsefalsefalse00falsefalsefalse73falsefalsefalse00falsefalsefalse74falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Pre-tax effect of derivatives designated as cash flow hedging instruments4false 5us-gaap_DerivativeInstrumentsGainLossRecognizedInOtherComprehensiveIncomeEffectivePortionNetus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3falsefalsefalse00falsefalsefalse4falsefalsefalse00falsefalsefalse5falsefalsefalse00falsefalsefalse6falsefalsefalse00falsefalsefalse7falsefalsefalse00falsefalsefalse8falsefalsefalse00falsefalsefalse9falsefalsefalse00falsefalsefalse10falsefalsefalse00falsefalsefalse11falsefalsefalse00falsefalsefalse12falsefalsefalse00falsefalsefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16falsefalsefalse00falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalse23falsefalsefalse00falsefalsefalse24falsefalsefalse00falsefalsefalse25falsefalsefalse00falsefalsefalse26falsefalsefalse00falsefalsefalse27falsefalsefalse00falsefalsefalse28falsefalsefalse00falsefalsefalse29falsefalsefalse00falsefalsefalse30falsefalsefalse00falsefalsefalse31falsefalsefalse00falsefalsefalse32falsefalsefalse00falsefalsefalse33falsefalsefalse00falsefalsefalse34falsefalsefalse00falsefalsefalse35falsefalsefalse00falsefalsefalse36falsefalsefalse00falsefalsefalse37falsefalsefalse00falsefalsefalse38falsefalsefalse00falsefalsefalse39falsefalsefalse00falsefalsefalse40falsefalsefalse00falsefalsefalse41falsefalsefalse00falsefalsefalse42falsefalsefalse00falsefalsefalse43falsefalsefalse00falsefalsefalse44falsefalsefalse00falsefalsefalse45falsefalsefalse00falsefalsefalse46falsefalsefalse00falsefalsefalse47falsefalsefalse00falsefalsefalse48falsefalsefalse00falsefalsefalse49falsefalsefalse00falsefalsefalse50falsefalsefalse00falsefalsefalse51falsefalsefalse00falsefalsefalse52falsefalsefalse00falsefalsefalse53falsefalsefalse00falsefalsefalse54falsefalsefalse00falsefalsefalse55falsefalsefalse00falsefalsefalse56falsefalsefalse00falsefalsefalse57falsefalsefalse00falsefalsefalse58falsefalsefalse00falsefalsefalse59falsefalsefalse00falsefalsefalse60falsefalsefalse00falsefalsefalse61falsefalsefalse00falsefalsefalse62falsefalsefalse00falsefalsefalse63truefalsefalse00falsefalsefalse64truefalsefalse-18000000-18falsefalsefalse65truefalsefalse00falsefalsefalse66truefalsefalse-12000000-12falsefalsefalse67truefalsefalse00falsefalsefalse68truefalsefalse-18000000-18falsefalsefalse69truefalsefalse00falsefalsefalse70truefalsefalse-11000000-11falsefalsefalse71truefalsefalse00falsefalsefalse72truefalsefalse00falsefalsefalse73truefalsefalse00falsefalsefalse74truefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959 false2Gain (Loss) Recognized in OCI on Derivative (Effective Portion)5false 5us-gaap_DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNetus-gaap_truecreditdurationfalsefalsefalsefalsefalsefalsefalsefalseverboseLabel1truefalsefalse-5000000-5USD$falsetruefalse2truefalsefalse-4000000-4USD$falsetruefalse3truefalsefalse-10000000-10USD$falsetruefalse4truefalsefalse-7000000-7USD$falsetruefalse5truefalsefalse-1000000-1USD$falsetruefalse6truefalsefalse00USD$falsetruefalse7truefalsefalse-1000000-1USD$falsetruefalse8truefalsefalse00USD$falsetruefalse9truefalsefalse-3000000-3USD$falsetruefalse10truefalsefalse-3000000-3USD$falsetruefalse11truefalsefalse-6000000-6USD$falsetruefalse12truefalsefalse-5000000-5USD$falsetruefalse13falsefalsefalse00falsefalsefalse14falsefalsefalse00falsefalsefalse15falsefalsefalse00falsefalsefalse16falsefalsefalse00falsefalsefalse17falsefalsefalse00falsefalsefalse18falsefalsefalse00falsefalsefalse19falsefalsefalse00falsefalsefalse20falsefalsefalse00falsefalsefalse21falsefalsefalse00falsefalsefalse22falsefalsefalse00falsefalsefalse23falsefalsefalse00falsefalsefalse24falsefalsefalse00falsefalsefalse25falsefalsefalse00falsefalsefalse26falsefalsefalse00falsefalsefalse27falsefalsefalse00falsefalsefalse28falsefalsefalse00falsefalsefalse29falsefalsefalse00falsefalsefalse30falsefalsefalse00falsefalsefalse31falsefalsefalse00falsefalsefalse32falsefalsefalse00falsefalsefalse33falsefalsefalse00falsefalsefalse34falsefalsefalse00falsefalsefalse35falsefalsefalse00falsefalsefalse36falsefalsefalse00falsefalsefalse37falsefalsefalse00falsefalsefalse38falsefalsefalse00falsefalsefalse39falsefalsefalse00falsefalsefalse40falsefalsefalse00falsefalsefalse41falsefalsefalse00falsefalsefalse42falsefalsefalse00falsefalsefalse43falsefalsefalse00falsefalsefalse44falsefalsefalse00falsefalsefalse45falsefalsefalse00falsefalsefalse46falsefalsefalse00falsefalsefalse47falsefalsefalse00falsefalsefalse48falsefalsefalse00falsefalsefalse49falsefalsefalse00falsefalsefalse50falsefalsefalse00falsefalsefalse51falsefalsefalse00falsefalsefalse52falsefalsefalse00falsefalsefalse53falsefalsefalse00falsefalsefalse54falsefalsefalse00falsefalsefalse55falsefalsefalse00falsefalsefalse56falsefalsefalse00falsefalsefalse57falsefalsefalse00falsefalsefalse58falsefalsefalse00falsefalsefalse59falsefalsefalse00falsefalsefalse60falsefalsefalse00falsefalsefalse61falsefalsefalse00falsefalsefalse62falsefalsefalse00falsefalsefalse63falsefalsefalse00falsefalsefalse64falsefalsefalse00falsefalsefalse65falsefalsefalse00falsefalsefalse66falsefalsefalse00falsefalsefalse67falsefalsefalse00falsefalsefalse68falsefalsefalse00falsefalsefalse69falsefalsefalse00falsefalsefalse70falsefalsefalse00falsefalsefalse71falsefalsefalse00falsefalsefalse72falsefalsefalse00falsefalsefalse73falsefalsefalse00falsefalsefalse74falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624171-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4D -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624177-113959 false2Gain (Loss) Reclassified from AOCI into Income (Effective Portion)falseDerivatives - Pre-tax Effects of Derivatives Designated as Cash Flow Hedging Instruments (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://southerncompany.com/role/DerivativesPreTaxEffectsOfDerivativesDesignatedAsCashFlowHedgingInstrumentsDetails745