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available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseComponents Of Income From Leveraged lease4false0us-gaap_LeveragedLeasesIncomeStatementNetIncomeFromLeveragedLeasesus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse1800000018falsetruefalsefalsefalse2truefalsefalse3100000031falsetruefalsefalsefalse3truefalsefalse-85000000-85falsetruefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe total recognized during the period for income on leases meeting the criteria for classification as leveraged leases.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 13 -Paragraph 47 truefalseNet leveraged lease income (loss)5false0natruenanaNo definition available.falsetruefalsefalsefalsefalsefalsefalsefalsefalsehttp://southerncompany.com/role/summaryofsignificantaccountingpoliciesdetails4abstract1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalse4falsefalseUSDtruefalse{so_LeveragedLeasesAxis} : Domestic Leveraged Lease [Member] 1/1/2010 - 12/31/2010 USD ($) $TwelveMonthsEnded_31Dec2010_Domestic_Leveraged_Lease_Memberhttp://www.sec.gov/CIK0000092122duration2010-01-01T00:00:002010-12-31T00:00:00falsefalseDomestic Leveraged Lease [Member]so_LeveragedLeasesAxisxbrldihttp://xbrl.org/2006/xbrldiso_DomesticLeveragedLeaseMemberso_LeveragedLeasesAxisexplicitMemberUSDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$5falsefalseUSDtruefalse{so_LeveragedLeasesAxis} : Domestic Leveraged Lease [Member] 1/1/2009 - 12/31/2009 USD ($) 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[Member]6true0us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNetAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseNet Investments From Leveraged lease7false0us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureRentalReceivablesNetus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse475000000475falsefalsefalsefalsefalse2truefalsefalse487000000487falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThis element represents leveraged lease rentals receivable, net of that portion of the rental applicable to principal and interest on the nonrecourse debt.Reference 1: 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available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse268000000268falsefalsefalsefalsefalse2truefalsefalse269000000269falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net investment in arrangements meeting the criteria to be classified as leveraged excluding deferred taxes.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 13 -Paragraph 47 falsefalseInvestment in leveraged leases10false0us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureDeferredTaxesArisingFromLeveragedLeasesus-gaaptruecreditinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse-223000000-223falsefalsefalsefalsefalse2truefalsefalse-211000000-211falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryTaxes arising from arrangements meeting the criteria for classification as leveraged leases due to timing differences between accounting and tax income recognition.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 13 -Paragraph 43 truefalseDeferred taxes from leveraged leases11false0us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNetus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse4500000045falsefalsefalsefalsefalse2truefalsefalse5800000058falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net investment in arrangements meeting the criteria for classification as leveraged leases including deferred taxes.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 13 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available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse-40000000-40falsefalsefalsefalsefalse2truefalsefalse-40000000-40falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryTaxes arising from arrangements meeting the criteria for classification as leveraged leases due to timing differences between accounting and tax income recognition.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 13 -Paragraph 43 truefalseDeferred taxes from leveraged leases23false0us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNetus-gaaptruedebitinstantNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalsetotallabel1truefalsefalse316000000316falsefalsefalsefalsefalse2truefalsefalse301000000301falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryThe net investment in arrangements meeting the criteria for classification as leveraged leases including deferred taxes.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 13 -Paragraph 43 truefalseNet investment in leveraged leases24true0us-gaap_LeveragedLeasesIncomeStatementNetIncomeFromLeveragedLeasesAbstractus-gaaptruenadurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00falsefalsefalsefalsefalse2falsefalsefalse00falsefalsefalsefalsefalse3falsefalsefalse00falsefalsefalsefalsefalseOtherxbrli:stringItemTypestringNo definition available.falsefalseComponents Of Income From Leveraged lease25false0us-gaap_LeveragedLeasesIncomeStatementIncomeFromLeveragedLeasesus-gaaptruecreditdurationNo definition available.falsefalsefalsefalsefalsefalsefalsefalsefalsefalseverboselabel1truefalsefalse1400000014falsefalsefalsefalsefalse2truefalsefalse1900000019falsefalsefalsefalsefalse3truefalsefalse-99000000-99falsefalsefalsefalsefalseMonetaryxbrli:monetaryItemTypemonetaryPretax lease income allocated in proportionate amounts from unearned income.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 13 -Paragraph 47 falsefalsePretax leveraged lease income (loss)26false0us-gaap_LeveragedLeasesIncomeStatementIncomeTaxExpenseOnLeveragedLeasesus-gaaptruedebitdurationNo definition 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meeting the criteria for classification as leveraged leases.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 13 -Paragraph 47 truefalseNet leveraged lease income (loss)325Summary of Significant Accounting Policies (Details 4) (USD $)MillionsUnKnownUnKnownUnKnownfalsetrue