2.2.0.7 false Condensed Consolidated Statements of Cash Flows (Unaudited) (USD $) 0120 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited) true false In Thousands false false 1 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 USD false false USD Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Shares Standard http://www.xbrl.org/2003/instance shares xbrli 0 USDEPS Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Pure Standard http://www.xbrl.org/2003/instance pure xbrli 0 $ 3 Operating Activities: 1 us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract us-gaap true na duration No definition available. 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 xbrli:stringItemType string The net cash from (used in) all of the entity's operating activities, including those of discontinued operations, of the reporting entity. Operating activities include all transactions and events that are not defined as investing or financing activities. Operating activities generally involve producing and delivering goods and providing services. Cash flows from operating activities are generally the cash effects of transactions and other events that enter into the determination of net income. false 4 Consolidated net income 2 us-gaap_ProfitLoss us-gaap true credit duration No definition available. false false false false false false false false false false false verboselabel false 1 true true false false 1037092000 1037092 false false false 2 true true false false 636724000 636724 false false false xbrli:monetaryItemType monetary The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph A1, A4, A5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 5 -Subparagraph b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 29 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph a Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph c(1) false 5 Adjustments to reconcile consolidated net income to net cash provided from operating activities - 2 us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract us-gaap true na duration No definition available. 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 xbrli:stringItemType string No definition available. false 6 Depreciation and amortization, total 3 us-gaap_DepreciationAmortizationAndAccretionNet us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 867583000 867583 false false false 2 false true false false 895354000 895354 false false false xbrli:monetaryItemType monetary The aggregate net amount of depreciation, amortization, and accretion recognized during an accounting period. As a noncash item, the net amount is added back to net income when calculating cash provided by (used in) operations using the indirect method. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 7 Deferred income taxes 3 us-gaap_DeferredIncomeTaxExpenseBenefit us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 215318000 215318 false false false 2 false true false false -13807000 -13807 false false false xbrli:monetaryItemType monetary The component of income tax expense for the period representing the net change in the entity's deferred tax assets and liabilities pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 6 -Section I -Subsection 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 45 -Subparagraph b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 109 -Paragraph 289 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph h -Article 4 false 8 Deferred revenues 3 us-gaap_RecognitionOfDeferredRevenue us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -47361000 -47361 false false false 2 false true false false -26295000 -26295 false false false xbrli:monetaryItemType monetary The amount of previously reported deferred or unearned revenue that was recognized as revenue during the period. For cash flows, this element primarily pertains to amortization of deferred credits on long-term arrangements. As a noncash item, it is deducted from net income when calculating cash provided by (used in) operations using the indirect method. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 13 -Section A -Subsection 1 false 9 Allowance for equity funds used during construction 3 so_AllowanceForEquityFundsUsedDuringConstruction so false credit duration Total increase in earnings in the period representing the cost of equity (rate of return) used to finance construction of... false false false false false false false false false false true negated false 1 false true false false -94691000 -94691 false false false 2 false true false false -90112000 -90112 false false false xbrli:monetaryItemType monetary Total increase in earnings in the period representing the cost of equity (rate of return) used to finance construction of regulated assets, which is expected to be recovered through rate adjustments. No authoritative reference available. false 10 Leveraged lease income (losses) 3 us-gaap_LeveragedLeasesIncomeStatementNetIncomeFromLeveragedLeases us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -6800000 -6800 false false false 2 false true false false -18117000 -18117 false false false xbrli:monetaryItemType monetary The 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 false 11 Gain on disposition of lease termination 3 us-gaap_GainLossOnContractTermination us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false false false false 0 0 false false false 2 false true false false -26300000 -26300 false false false xbrli:monetaryItemType monetary This element represents the income received from or payment made to a third party in connection with the termination of a contract between the parties. The termination may be due to many causes including early termination of a lease by a lessee, a breach of contract by one or the other party, a failure to perform. No authoritative reference available. false 12 Loss on extinguishment of debt 3 us-gaap_GainsLossesOnExtinguishmentOfDebtBeforeWriteOffOfDeferredDebtIssuanceCost us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false false false false 0 0 false false false 2 false true false false 17184000 17184 false false false xbrli:monetaryItemType monetary Reflects the difference between the fair value of payments made to legally extinguish a debt and its carrying value at that time. This item excludes the write-off of amounts previously capitalized as debt issuance costs. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Principles Board Opinion (APB) -Number 26 -Paragraph 20, 21 false 13 Pension, postretirement, and other employee benefits 3 us-gaap_PensionAndOtherPostretirementBenefitExpense us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -1252000 -1252 false false false 2 false true false false -10939000 -10939 false false false xbrli:monetaryItemType monetary The amount of pension and other (such as medical, dental and life insurance) postretirement benefit costs recognized during the period for (1) defined benefit plans (periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain or loss on assets, prior service cost or credit, transition asset or obligation, and gain or loss due to settlements or curtailments) and for (2) defined contribution plans (to the extent that a plan's defined contributions to an individual's account are to be made for periods in which that individual renders services, the net cost for a period shall be the contribution called for in that period; if a plan calls for contributions for periods after an individual retires or terminates, the estimated cost shall be accrued during the employee's service period). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5 -Subparagraph h Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 132R -Paragraph 5, 11 false 14 Stock based compensation expense 3 us-gaap_StockOptionPlanExpense us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 23809000 23809 false false false 2 false true false false 18956000 18956 false false false xbrli:monetaryItemType monetary The noncash expense that accounts for the value of stock options distributed to employees as compensation. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph 64 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 123R -Paragraph A240 -Subparagraph i false 15 Hedge settlements 3 so_HedgeSettlements so false credit duration The cash outflow (inflow) for a financial contract that settles in the period relating to operating activities. false false false false false false false false false false true negated false 1 false true false false 1530000 1530 false false false 2 false true false false -16167000 -16167 false false false xbrli:monetaryItemType monetary The cash outflow (inflow) for a financial contract that settles in the period relating to operating activities. No authoritative reference available. false 16 Generation construction screening costs 3 so_CertainRegulatoryAssets so false credit duration The net change during the reporting period in the value of certain assets that are created when regulatory agencies permits... false false false false false false false false false false true negated false 1 false true false false -50554000 -50554 false false false 2 false true false false -14049000 -14049 false false false xbrli:monetaryItemType monetary The net change during the reporting period in the value of certain assets that are created when regulatory agencies permits public utilities to defer costs to the balance sheet. No authoritative reference available. false 17 Other, net 3 us-gaap_AdjustmentsNoncashItemsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesOther us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -57830000 -57830 false false false 2 false true false false 42293000 42293 false false false xbrli:monetaryItemType monetary Transactions that do not result in cash inflows or outflows in the period in which they occur, but affect net income and thus are removed when calculating net cash flow from operating activities using the indirect cash flow method. This element is used when there is not a more specific and appropriate element. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 18 Changes in certain current assets and liabilities - 3 us-gaap_IncreaseDecreaseInOperatingCapitalAbstract us-gaap true na duration No definition available. 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 xbrli:stringItemType string No definition available. false 19 -Receivables 4 us-gaap_IncreaseDecreaseInReceivables us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -255399000 -255399 false false false 2 false true false false 74770000 74770 false false false xbrli:monetaryItemType monetary The net change during the reporting period in the total amount due within one year (or one operating cycle) from all parties, associated with underlying transactions that are classified as operating activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 20 -Fossil fuel stock 4 us-gaap_IncreaseDecreaseInFossilFuelInventories us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false 72216000 72216 false false false 2 false true false false -375888000 -375888 false false false xbrli:monetaryItemType monetary The net change during the reporting period in the value of fossil fuel held in inventory. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 21 -Materials and supplies 4 us-gaap_IncreaseDecreaseInRawMaterialsPackagingMaterialsAndSuppliesInventories us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -6806000 -6806 false false false 2 false true false false -20079000 -20079 false false false xbrli:monetaryItemType monetary The net change during the reporting period in the value of raw materials, packaging materials and supplies held in inventory. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 22 -Other current assets 4 us-gaap_IncreaseDecreaseInOtherOperatingAssets us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -88138000 -88138 false false false 2 false true false false -96394000 -96394 false false false xbrli:monetaryItemType monetary The net change during the reporting period in other operating assets not otherwise defined in the taxonomy. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 23 -Accounts payable 4 us-gaap_IncreaseDecreaseInAccountsPayable us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -52091000 -52091 false false false 2 false true false false 14711000 14711 false false false xbrli:monetaryItemType monetary The net change during the reporting period in the aggregate amount of obligations due within one year (or one business cycle). This may include trade payables, amounts due to related parties, royalties payable, and other obligations. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 24 -Accrued taxes 4 so_IncreaseDecreaseInAccruedTaxes so false debit duration The net change during the period in the amount of cash payments due to taxing authorities for income and nonincome-related... false false false false false false false false false false false verboselabel false 1 false true false false -79767000 -79767 false false false 2 false true false false -140308000 -140308 false false false xbrli:monetaryItemType monetary The net change during the period in the amount of cash payments due to taxing authorities for income and nonincome-related taxes. No authoritative reference available. false 25 -Accrued compensation 4 us-gaap_IncreaseDecreaseInAccruedSalaries us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -33932000 -33932 false false false 2 false true false false -298670000 -298670 false false false xbrli:monetaryItemType monetary Net change during the period in the amount of salaries accrued at the period end. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 false 26 -Other current liabilities 4 us-gaap_IncreaseDecreaseInOtherOperatingLiabilities 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 -27965000 -27965 false false false 2 false true false false 66748000 66748 false false false xbrli:monetaryItemType monetary The net change during the reporting period in other operating obligations not otherwise defined in the taxonomy. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 true 27 Net cash provided from operating activities 3 us-gaap_NetCashProvidedByUsedInOperatingActivities us-gaap true na duration No definition available. false false false false false false false false false false false totallabel false 1 false true false false 1414962000 1414962 false false false 2 false true false false 619615000 619615 false false false xbrli:monetaryItemType monetary The net cash from (used in) all of the entity's operating activities, including those of discontinued operations, of the reporting entity. Operating activities generally involve producing and delivering goods and providing services. Operating activity cash flows include transactions, adjustments, and changes in value that are not defined as investing or financing activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 28 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 true 28 Investing Activities: 1 us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract us-gaap true na duration No definition available. 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 xbrli:stringItemType string No definition available. false 29 Property additions 2 us-gaap_PaymentsToAcquirePropertyPlantAndEquipment us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -1935716000 -1935716 false false false 2 false true false false -2192959000 -2192959 false false false xbrli:monetaryItemType monetary The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 17 -Subparagraph c false 30 Investment in restricted cash from pollution control revenue bonds 2 us-gaap_PaymentsForInvestmentInRestrictedCashFromPollutionControlBond us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -11000 -11 false false false 2 false true false false -49478000 -49478 false false false xbrli:monetaryItemType monetary The cash outflow for investments in restricted cash from pollution control bond, which is a debt security issued by a state, certain agencies or authorities, a local government, or development corporation to finance the construction of air- or water-pollution control facilities or sewage or solid waste disposal facilities pursuant to federal law. The bonds are backed by the credit of the beneficiary of the financing rather than the credit of the issuer. New issues of these bonds are prohibited under the 1986 Tax Law. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 17 false 31 Distribution of restricted cash from pollution control revenue bonds 2 us-gaap_ProceedsFromDistributionOfRestrictedCashFromPollutionControlBond us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 11403000 11403 false false false 2 false true false false 59741000 59741 false false false xbrli:monetaryItemType monetary The cash inflow from amounts received from distributions of restricted cash from pollution control bond, which is a debt security issued by a state, certain agencies or authorities, a local government, or development corporation to finance the construction of air- or water-pollution control facilities or sewage or solid waste disposal facilities pursuant to federal law. The bonds are backed by the credit of the beneficiary of the financing rather than the credit of the issuer. New issues of these bonds are prohibited under the 1986 Tax Law. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 false 32 Nuclear decommissioning trust fund purchases 2 us-gaap_PaymentsToInvestInDecommissioningFund us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -515901000 -515901 false false false 2 false true false false -823416000 -823416 false false false xbrli:monetaryItemType monetary The cash outflow from the costs of decontaminating and decommissioning of facilities through collection of revenues derived from utility assessments, government appropriations, and so forth. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15, 17 false 33 Nuclear decommissioning trust fund sales 2 us-gaap_ProceedsFromDecommissioningFund us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 488561000 488561 false false false 2 false true false false 788690000 788690 false false false xbrli:monetaryItemType monetary The cash inflow from the costs of decontaminating and decommissioning of facilities through collection of revenues derived from utility assessments, government appropriations, and so forth. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15, 16 false 34 Proceeds from property sales 2 us-gaap_ProceedsFromSaleOfProductiveAssets us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 216000 216 false false false 2 false true false false 339903000 339903 false false false xbrli:monetaryItemType monetary The cash inflow from the sale of property, plant and equipment (capital expenditures), software, and other intangible assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 16 -Subparagraph c false 35 Cost of removal, net of salvage 2 us-gaap_PaymentsForProceedsFromRemovalCosts us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -59989000 -59989 false false false 2 false true false false -63705000 -63705 false false false xbrli:monetaryItemType monetary The net cash inflow (outflow) from the costs of disposing of plant, whether by demolishing, dismantling, abandoning, sale, and so forth during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15, 16, 17 false 36 Change in construction payables 2 so_ChangeInConstructionPayables so false debit duration The net change during the reporting period in the aggregate amount of construction obligations due within one year (or one... false false false false false false false false false false false verboselabel false 1 false true false false 12934000 12934 false false false 2 false true false false 128101000 128101 false false false xbrli:monetaryItemType monetary The net change during the reporting period in the aggregate amount of construction obligations due within one year (or one business cycle). This includes accounts payable related to construction activities. No authoritative reference available. false 37 Other investing activities 2 us-gaap_PaymentsForProceedsFromOtherInvestingActivities us-gaap true credit duration No definition available. false false false false false false false false false false true negatedtotal false 1 false true false false -37037000 -37037 false false false 2 false true false false 8063000 8063 false false false xbrli:monetaryItemType monetary The net cash outflow (inflow) from other investing activities. This element is used when there is not a more specific and appropriate element in the taxonomy. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 15 true 38 Net cash used for investing activities 2 us-gaap_NetCashProvidedByUsedInInvestingActivities 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 -2035540000 -2035540 false false false 2 false true false false -1805060000 -1805060 false false false xbrli:monetaryItemType monetary The net cash inflow (outflow) from investing activity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 true 39 Financing Activities: 1 us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract us-gaap true na duration No definition available. 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 xbrli:stringItemType string No definition available. false 40 Increase in notes payable, net 2 us-gaap_ProceedsFromRepaymentsOfShortTermDebt us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 244037000 244037 false false false 2 false true false false 148090000 148090 false false false xbrli:monetaryItemType monetary The net cash inflow (outflow) for borrowing having initial term of repayment within one year or the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 false 41 Proceeds - 2 so_ProceedsAbstract so false na duration Proceeds. 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 xbrli:stringItemType string Proceeds. false 42 Long-term debt issuances 3 us-gaap_ProceedsFromIssuanceOfLongTermDebtAndCapitalSecuritiesNet us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 1146000000 1146000 false false false 2 false true false false 1785474000 1785474 false false false xbrli:monetaryItemType monetary The cash inflow associated with security instrument that either represents a creditor or an ownership relationship with the holder of the investment security with a maturity of beyond one year or normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 19 -Subparagraph b Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 19 -Subparagraph a false 43 Common stock issuances 3 us-gaap_ProceedsFromIssuanceOfCommonStock us-gaap true debit duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false 341447000 341447 false false false 2 false true false false 539088000 539088 false false false xbrli:monetaryItemType monetary The cash inflow from the additional capital contribution to the entity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 19 -Subparagraph a false 44 Redemptions - 2 so_RedemptionsAbstract so false na duration Redemptions. 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 xbrli:stringItemType string Redemptions. false 45 Long-term debt 3 us-gaap_RepaymentsOfLongTermDebtAndCapitalSecurities us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -754304000 -754304 false false false 2 false true false false -199929000 -199929 false false false xbrli:monetaryItemType monetary The cash outflow associated with security instrument that either represents a creditor or an ownership relationship with the holder of the investment security with a maturity of beyond one year or normal operating cycle, if longer. The nature of such security interests included herein may consist of debt securities, long-term capital lease obligations, and capital securities. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph b false 46 Payment of common stock dividends 2 us-gaap_PaymentsOfDividendsCommonStock us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -735009000 -735009 false false false 2 false true false false -670226000 -670226 false false false xbrli:monetaryItemType monetary The cash outflow from the distribution of an entity's earnings in the form of dividends to common shareholders. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph a false 47 Payment of dividends on preferred and preference stock of subsidiaries 2 us-gaap_PaymentsOfDividendsMinorityInterest us-gaap true credit duration No definition available. false false false false false false false false false false true negated false 1 false true false false -32394000 -32394 false false false 2 false true false false -32465000 -32465 false false false xbrli:monetaryItemType monetary The cash outflow for the return on capital for noncontrolled interest in the entity. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 20 -Subparagraph a false 48 Other financing activities 2 us-gaap_ProceedsFromPaymentsForOtherFinancingActivities 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 -12643000 -12643 false false false 2 false true false false -19327000 -19327 false false false xbrli:monetaryItemType monetary The net cash inflow (outflow) from other financing activities. This element is used when there is not a more specific and appropriate element in the taxonomy. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 18, 19, 20 true 49 Net cash provided from financing activities 2 us-gaap_NetCashProvidedByUsedInFinancingActivities 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 197134000 197134 false false false 2 false true false false 1550705000 1550705 false false false xbrli:monetaryItemType monetary The net cash inflow (outflow) from financing activity for the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 true 50 Net Change in Cash and Cash Equivalents 1 us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease us-gaap true na duration No definition available. false false false false false false false false false false false verboselabel false 1 false true false false -423444000 -423444 false false false 2 false true false false 365260000 365260 false false false xbrli:monetaryItemType monetary The net change between the beginning and ending balance of cash and cash equivalents. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 26 false 51 Cash and Cash Equivalents at Beginning of Period 1 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant No definition available. false false false false false false false false true false false periodstartlabel false 1 false true false false 689722000 689722 false false false 2 false true false false 416581000 416581 false false false xbrli:monetaryItemType monetary Includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits should not be reported as cash and cash equivalents. Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7, 26 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 8, 9 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 95 -Paragraph 7 -Footnote 1 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 1 -Article 5 false 52 Cash and Cash Equivalents at End of Period 1 us-gaap_CashAndCashEquivalentsAtCarryingValue us-gaap true debit instant No definition available. false false false false false false false false false true false periodendlabel false 1 false true false false 266278000 266278 false false false 2 false true false false 781841000 781841 false false false xbrli:monetaryItemType monetary Includes currency on hand as well as demand deposits with banks or financial institutions. It also includes other kinds of accounts that have the general characteristics of demand deposits in that the Entity may deposit additional funds at any time and also effectively may withdraw funds at any time without prior notice or penalty. Cash equivalents, excluding items classified as marketable securities, include short-term, highly liquid investments that are both readily convertible to known amounts of cash, and so near their maturity that they present minimal risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three years ago does not become a cash equivalent when its remaining maturity is three months. Compensating balance arrangements that do not legally restrict the withdrawal or usage of cash amounts may be reported as Cash and Cash Equivalents, while legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits should not be reported as cash and cash equivalents. 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