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definition available. false false false false false true false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:stringItemType string No definition available. false 6 Unrecognized tax benefits as of December 31, 2009 4 us-gaap_UnrecognizedTaxBenefits us-gaap true credit instant No definition available. false false false false false false false false true false false periodstartlabel false 1 true true false false 199000000 199 false false false 2 false false false false 0 0 false false false 3 true true false false 6000000 6 true false false 4 true true false false 6000000 6 true false false 5 true true false false 181000000 181 true false false 6 false false false false 0 0 true false false 7 true true false false 2000000 2 true false false 8 true true false false 2000000 2 true false false 9 true true false false 3000000 3 true false false 10 true true false false 3000000 3 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 true true false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary The gross amount of unrecognized tax benefits (tax reductions recognized in financial reports but excluded from tax returns) pertaining to uncertain tax positions taken in tax returns as of the beginning balance sheet date, excluding amounts pertaining to examined tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 21 -Subparagraph a false 7 Tax positions from current periods 4 us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromCurrentPeriodTaxPositions us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 23000000 23 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false 22000000 22 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary The gross amount of increases in unrecognized tax benefits resulting from tax positions that have been or will be taken in the tax return for the current period, excluding amounts pertaining to examined tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 21 -Subparagraph a(2) false 8 Tax positions from prior periods 4 us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromPriorPeriodTaxPositions us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -27000000 -27 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false -23000000 -23 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary The gross amount of increases in unrecognized tax benefits resulting from tax positions taken in prior period tax returns, excluding amounts pertaining to examined tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 21 -Subparagraph a(1) false 9 Unrecognized tax benefits as of June 30, 2010 4 us-gaap_UnrecognizedTaxBenefits us-gaap true credit instant No definition available. false false false false false false false false false true false periodendlabel false 1 false true false false 195000000 195 false false false 2 false false false false 0 0 false false false 3 false true false false 6000000 6 true false false 4 false true false false 6000000 6 true false false 5 false true false false 180000000 180 true false false 6 false false false false 0 0 true false false 7 false true false false 2000000 2 true false false 8 false true false false 2000000 2 true false false 9 false true false false 3000000 3 true false false 10 false true false false 3000000 3 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false true false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary The gross amount of unrecognized tax benefits (tax reductions recognized in financial reports but excluded from tax returns) pertaining to uncertain tax positions taken in tax returns as of the beginning balance sheet date, excluding amounts pertaining to examined tax returns. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 21 -Subparagraph a false 10 Accrued interest for unrecognized tax benefits 3 so_AccruedInterestForUnrecognizedTaxBenefitsAbstract so false na duration Accrued interest for unrecognized tax benefits Abstract. false false false false false true false false false false false verboselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:stringItemType string Accrued interest for unrecognized tax benefits Abstract. false 11 Interest accrued as of December 31, 2009 4 us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued us-gaap true credit instant No definition available. false false false false false false false false true false false periodstartlabel false 1 false true false false 21000000 21 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false 20000000 20 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false true false false 1000000 1 true false false 12 false true false false 1000000 1 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary This element represents the amount of interest expense accrued as of the date of the statement of financial position for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 21 -Subparagraph c Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 15 false 12 Interest accrued during the period 4 us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesExpense us-gaap true debit duration No definition available. false false false false false false false false false false false totallabel false 1 false true false false 2000000 2 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false true false false 2000000 2 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary This element represents interest expense recognized for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 21 -Subparagraph c Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Interpretation (FIN) -Number 48 -Paragraph 15 true 13 Balance as of June 30, 2010 4 us-gaap_UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued us-gaap true credit instant No definition available. false false false false false false false false false true false periodendlabel false 1 true true false false 23000000 23 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 true true false false 22000000 22 true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 true true false false 1000000 1 true false false 12 true true false false 1000000 1 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:monetaryItemType monetary This element represents the amount of interest expense accrued as of the date of the statement of financial position for an underpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity. 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No authoritative reference available. false 17 Significantly increase or decrease in the amount of the unrecognized tax benefits associated with a majority of Southern 4 so_SignificantlyIncreaseOrDecreaseInAmountOfUnrecognizedTaxBenefits so false na duration Significantly increase or decrease in the amount of the unrecognized tax benefits. false false false false false false false false false false false verboselabel false 1 false false false false 0 0 Next 12 Months Next 12 Months false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false 5 false false false false 0 0 Next 12 Months Next 12 Months true false false 6 false false false false 0 0 true false false 7 false false false false 0 0 true false false 8 false false false false 0 0 true false false 9 false false false false 0 0 true false false 10 false false false false 0 0 true false false 11 false false false false 0 0 true false false 12 false false false false 0 0 true false false 13 false false false false 0 0 true false false 14 false false false false 0 0 true false false xbrli:stringItemType string Significantly increase or decrease in the amount of the unrecognized tax benefits. No authoritative reference available. false 14 13 false Millions UnKnown UnKnown false true