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false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. false 7 Long-term debt payable to 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false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. 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No authoritative reference available. false 9 Long-term senior notes and debt -- 5 us-gaap_LongTermDebtAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. false 10 2009 6 so_LongTermDebtMaturitiesRepaymentsOfPrincipalInLastTwelveMonths so false credit instant monetary Amount of long-term debt matured in the past twelve months following the date of the latest balance sheet presented in... false false false false false false false false false 1 false false 0 0 false false 2 false true 128000000 128 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false true 440000000 440 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false Amount of long-term debt matured in the past twelve months following the date of the latest balance sheet presented in the financial statements, which may include maturities of longterm debt, sinking fund requirements, and other securities redeemable at fixed or detereminable prices and dates. 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No authoritative reference available. false 13 2012 6 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 1778000000 1778 false false 2 false true 1778000000 1778 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 14 2013 6 us-gaap_LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 936000000 936 false false 2 false true 936000000 936 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. 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No authoritative reference available. false 17 Total long-term senior notes and debt 6 so_TotalLongTermSeniorNotesAndDebt so false credit instant monetary Including the current and noncurrent portions, carrying value as of the balance sheet date of Long-term Notes and Other... false false false false false false false false false 1 false true 15172000000 15172 false false 2 false true 13648000000 13648 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false Including the current and noncurrent portions, carrying value as of the balance sheet date of Long-term Notes and Other Long-term Debt with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer). Senior note holders are paid off in full before any payments are made to junior note holders. No authoritative reference available. true 18 Interest Rates, Minimum 6 us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMinimum us-gaap true na duration pure No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false true 0.0068 0.0068 true false 4 false false 0 0 true false 5 false true 0.0035 0.0035 true false 6 false false 0 0 true false 7 false true 0.023288 0.023288 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false true 0.0018 0.0018 true false 16 false false 0 0 true false 17 false true 0.014 0.014 true false 18 false true 0.014 0.014 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false true 0.0425 0.0425 true false 25 false true 0.0425 0.0425 true false 26 false true 0.0415 0.0415 true false 27 false true 0.0415 0.0415 true false 28 false true 0.0435 0.0435 true false 29 false true 0.0435 0.0435 true false 30 false true 0.0485 0.0485 true false 31 false true 0.0485 0.0485 true false 32 false true 0.04 0.04 true false 33 false true 0.04 0.04 true false 34 false true 0.047 0.047 true false 35 false true 0.047 0.047 true false 36 false true 0.041 0.041 true false 37 false true 0.041 0.041 true false No definition available. No authoritative reference available. false 19 Interest Rates, Maximum 6 us-gaap_DebtInstrumentInterestRateStatedPercentageRateRangeMaximum us-gaap true na duration pure No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false true 0.0295 0.0295 true false 4 false false 0 0 true false 5 false true 0.0097 0.0097 true false 6 false false 0 0 true false 7 false true 0.0236 0.0236 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false true 0.0044 0.0044 true false 16 false false 0 0 true false 17 false true 0.06 0.06 true false 18 false true 0.06 0.06 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false true 0.082 0.082 true false 25 false true 0.082 0.082 true false 26 false true 0.049 0.049 true false 27 false true 0.049 0.049 true false 28 false true 0.06 0.06 true false 29 false true 0.06 0.06 true false 30 false true 0.0625 0.0625 true false 31 false true 0.0625 0.0625 true false 32 false true 0.0557 0.0557 true false 33 false true 0.0557 0.0557 true false 34 false true 0.047 0.047 true false 35 false true 0.047 0.047 true false 36 false true 0.07 0.07 true false 37 false true 0.07 0.07 true false No definition available. No authoritative reference available. false 21 Pollution control revenue bonds -- 5 us-gaap_LongtermPollutionControlBondCurrentAndNoncurrentAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. false 22 Long-term Pollution Control Bond, Total 6 us-gaap_LongtermPollutionControlBondCurrentAndNoncurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false true 1612000000 1612 true false 16 false true 1257000000 1257 true false 17 false true 1973000000 1973 true false 18 false true 2030000000 2030 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 23 Total other long-term debt 6 us-gaap_OtherLongTermDebt us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 3585000000 3585 false false 2 false true 3287000000 3287 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. true 24 Capitalized lease obligations 4 us-gaap_CapitalLeaseObligations us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 98000000 98 false false 2 false true 106000000 106 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. true 25 Unamortized debt (discount), net 4 us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true -23000000 -23 false false 2 false true -20000000 -20 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. true 26 Total long-term debt (annual interest requirement -- $ 894 million) 4 so_LongTermDebtAndCapitalLeaseObligationNetTotal so false credit instant monetary Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due... false false false false false false false false false 1 false true 19244000000 19244 false false 2 false true 17433000000 17433 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false Sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, plus capital lease obligations. No authoritative reference available. false 27 Less amount due within one year 4 us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 1113000000 1113 false false 2 false true 617000000 617 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 28 Long-term debt excluding amount due within one year 4 us-gaap_LongTermDebtAndCapitalLeaseObligations us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 18131000000 18131 false false 2 false true 16816000000 16816 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 29 Redeemable Preferred Stock of Subsidiaries: 3 so_RedeemablePreferredStockOfSubsidiariesAbstract so false na duration string Redeemable Preferred Stock of Subsidiaries. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false Redeemable Preferred Stock of Subsidiaries. false 30 Redeemable Preferred Stock 4 us-gaap_TemporaryEquityCarryingAmount us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 375000000 375 false false 2 false true 375000000 375 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 31 Common Stockholders' Equity: 3 us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract us-gaap true na duration string No definition available. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. false 32 Common stock, par value $5 per share 4 us-gaap_CommonStockValue us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 4101000000 4101 false false 2 false true 3888000000 3888 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 33 Paid-in capital 4 us-gaap_AdditionalPaidInCapitalCommonStock us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 2995000000 2995 false false 2 false true 1893000000 1893 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 34 Treasury, at cost 4 us-gaap_TreasuryStockValue us-gaap true debit instant monetary No definition available. false false false false false false false false false 1 false true -15000000 -15 false false 2 false true -12000000 -12 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 35 Retained earnings 4 us-gaap_RetainedEarningsAccumulatedDeficit us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 7885000000 7885 false false 2 false true 7612000000 7612 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 36 Accumulated other comprehensive income (loss) 4 us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true -88000000 -88 false false 2 false true -105000000 -105 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. true 37 Total common stockholders' equity 4 so_TotalCommonStockholdersEquity so false credit instant monetary Total of all Common Stockholders' Equity (deficit) items, net of receivables from officers, directors, owners, and affiliates... false false false false false false false false false 1 false true 14878000000 14878 false false 2 false true 13276000000 13276 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false Total of all Common Stockholders' Equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity. This excludes temporary equity and preferred and preference stockholders' equity. No authoritative reference available. true 38 Preferred and Preference Stock of Subsidiaries: 3 so_PreferredAndPreferenceStockOfSubsidiariesAbstract so false na duration string Preferred and Preference Stock of Subsidiaries. false false false false false true false false false 1 false false 0 0 false false 2 false false 0 0 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false Preferred and Preference Stock of Subsidiaries. false 39 Preferred Stock 4 us-gaap_MinorityInterest us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 707000000 707 false false 2 false true 707000000 707 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false true 319000000 319 true false 10 false true 319000000 319 true false 11 false true 343000000 343 true false 12 false true 343000000 343 true false 13 false true 45000000 45 true false 14 false true 45000000 45 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. false 40 Total Stockholders' Equity (See accompanying statements) 3 us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 false true 15585000000 15585 false false 2 false true 13983000000 13983 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. true 41 Total Capitalization 3 us-gaap_CapitalizationLongtermDebtAndEquity us-gaap true credit instant monetary No definition available. false false false false false false false false false 1 true true 34091000000 34091 false false 2 true true 31174000000 31174 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false No definition available. No authoritative reference available. true 42 Long-term debt excluding amount due within one year, in Percent of Total Capitalization 3 so_LongTermDebtAndCapitalLeaseObligationsInPercentOfTotalCapitalization so false na instant pure As a percent of total capitalization, the sum of the carrying values as of the balance sheet date of all long-term debt,... false false false false false false false false false 1 false true 0.532 0.532 false false 2 false true 0.539 0.539 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false As a percent of total capitalization, the sum of the carrying values as of the balance sheet date of all long-term debt, which is debt initially having maturities due after one year from the balance sheet date or beyond the operating cycle, if longer, but excluding the portions thereof scheduled to be repaid within one year or the normal operating cycle, if longer plus capital lease obligations due to be paid more than one year after the balance sheet date. No authoritative reference available. false 43 Total redeemable preferred stock of subsidiaries, in Percent of Total Capitalization 3 so_TemporaryEquityCarryingAmountInPercentOfTotalCapitalization so false na instant pure As a percent of total capitalization, the carrying value (book value) of an entity's issued and outstanding stock which is... false false false false false false false false false 1 false true 0.011 0.011 false false 2 false true 0.012 0.012 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false As a percent of total capitalization, the carrying value (book value) of an entity's issued and outstanding stock which is not included within permanent equity in Stockholders Equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with a put option held by an ESOP and stock redeemable by a holder only in the event of a change in control of the issuer. No authoritative reference available. false 44 Total common stockholders' equity, in percent of Total Capitalization 3 so_TotalCommonStockholdersEquityInPercentOfTotalCapitalization so false na instant pure As a percent of total capitalization, the total of all Common Stockholders' Equity (deficit) items, net of receivables from... false false false false false false false false false 1 false true 0.436 0.436 false false 2 false true 0.426 0.426 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false As a percent of total capitalization, the total of all Common Stockholders' Equity (deficit) items, net of receivables from officers, directors owners, and affiliates of the entity. This excludes temporary equity and preferred and preference stockholders' equity. No authoritative reference available. false 45 Total preferred and preference stock of subsidiaries, in Percent of Total Capitalization 3 so_MinorityInterestInPercentOfTotalCapitalization so false na instant pure As a percent of total capitalization, the total of all Stockholders' Equity (deficit) items, net of receivables from... false false false false false false false false false 1 false true 0.021 0.021 false false 2 false true 0.023 0.023 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false As a percent of total capitalization, the total of all Stockholders' Equity (deficit) items, net of receivables from officers, directors owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). No authoritative reference available. false 46 Total Capitalization, in Percent 3 so_TotalCapitalizationInPercent so false na instant pure Total Capitalization in Percent. false false false false false false false false false 1 false true 1 1 false false 2 false true 1 1 false false 3 false false 0 0 true false 4 false false 0 0 true false 5 false false 0 0 true false 6 false false 0 0 true false 7 false false 0 0 true false 8 false false 0 0 true false 9 false false 0 0 true false 10 false false 0 0 true false 11 false false 0 0 true false 12 false false 0 0 true false 13 false false 0 0 true false 14 false false 0 0 true false 15 false false 0 0 true false 16 false false 0 0 true false 17 false false 0 0 true false 18 false false 0 0 true false 19 false false 0 0 true false 20 false false 0 0 true false 21 false false 0 0 true false 22 false false 0 0 true false 23 false false 0 0 true false 24 false false 0 0 true false 25 false false 0 0 true false 26 false false 0 0 true false 27 false false 0 0 true false 28 false false 0 0 true false 29 false false 0 0 true false 30 false false 0 0 true false 31 false false 0 0 true false 32 false false 0 0 true false 33 false false 0 0 true false 34 false false 0 0 true false 35 false false 0 0 true false 36 false false 0 0 true false 37 false false 0 0 true false Total Capitalization in Percent. No authoritative reference available. false false 37 40 false Millions UnKnown UnKnown false true