XML 209 R165.htm IDEA: XBRL DOCUMENT
v3.22.0.1

FINANCING - Long-Term Debt (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Debt Instrument [Line Items] |  |
Long-term debt, gross | $ 52,100 | $ 48,300
Finance lease obligations | 215 | 231
Unamortized fair value adjustment | 359 | 393
Unamortized debt premium (discount), net | (216) | (201)
Unamortized debt issuance expense | (243) | (237)
Total long-term debt | 52,277 | 48,580
Less: Amount due within one year | 2,157 | 3,507
Long-Term Debt | $ 50,120 | 45,073
Senior notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 3.62% |
Long-term debt, gross | $ 33,120 | 30,850
Junior subordinated notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 4.00% |
Long-term debt, gross | $ 8,918 | 7,295
FFB loans |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 2.88% |
Long-term debt, gross | $ 4,962 | 4,618
Pollution control revenue bonds |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 1.05% |
Long-term debt, gross | $ 2,662 | 2,675
First mortgage bonds |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 3.53% |
Long-term debt, gross | $ 2,100 | 1,900
Medium-term notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 7.60% |
Long-term debt, gross | $ 130 | 160
Other long-term debt |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 0.79% |
Long-term debt, gross | $ 270 | 370
Other revenue bonds |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 0 | 320
Affiliated trusts |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 0 | 206
Alabama Power |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 9,700 | 8,900
Finance lease obligations | 4 | 5
Unamortized debt premium (discount), net | (18) | (16)
Unamortized debt issuance expense | (64) | (56)
Total long-term debt | 9,687 | 8,869
Less: Amount due within one year | 751 | 311
Long-Term Debt | $ 8,936 | 8,558
Alabama Power | Senior notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 3.89% |
Long-term debt, gross | $ 8,725 | 7,625
Alabama Power | Pollution control revenue bonds |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 0.55% |
Long-term debt, gross | $ 995 | 1,060
Alabama Power | Other long-term debt |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 1.24% |
Long-term debt, gross | $ 45 | 45
Alabama Power | Affiliated trusts |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 0 | 206
Georgia Power |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 13,600 | 12,800
Finance lease obligations | 136 | 145
Unamortized debt premium (discount), net | (11) | (12)
Unamortized debt issuance expense | (114) | (114)
Total long-term debt | 13,784 | 12,970
Less: Amount due within one year | 675 | 542
Long-Term Debt | $ 13,109 | 12,428
Georgia Power | Senior notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 3.61% |
Long-term debt, gross | $ 6,825 | 6,400
Georgia Power | Junior subordinated notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 5.00% |
Long-term debt, gross | $ 270 | 270
Georgia Power | FFB loans |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 2.88% |
Long-term debt, gross | $ 4,962 | 4,618
Georgia Power | Pollution control revenue bonds |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 1.33% |
Long-term debt, gross | $ 1,591 | 1,538
Georgia Power | Other long-term debt |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 0.70% |
Long-term debt, gross | $ 125 | 125
Mississippi Power |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 1,500 | 1,400
Finance lease obligations | 18 | 19
Unamortized debt premium (discount), net | 2 | 11
Unamortized debt issuance expense | (10) | (7)
Total long-term debt | 1,511 | 1,419
Less: Amount due within one year | 1 | 406
Long-Term Debt | $ 1,510 | 1,013
Mississippi Power | Senior notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 3.43% |
Long-term debt, gross | $ 1,425 | 900
Mississippi Power | Pollution control revenue bonds |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 1.86% |
Long-term debt, gross | $ 76 | 76
Mississippi Power | Other long-term debt |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 0 | 100
Mississippi Power | Other revenue bonds |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 0 | 320
Southern Power |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 3,700 | 3,700
Finance lease obligations | 0 | 0
Unamortized debt premium (discount), net | (6) | (6)
Unamortized debt issuance expense | (17) | (16)
Total long-term debt | 3,688 | 3,692
Less: Amount due within one year | 679 | 299
Long-Term Debt | 3,009 | 3,393
Fair value gain (loss) | 5 | 109
Derivative notional amount, receive | $ 1,100 |
Southern Power | Senior notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 3.74% |
Long-term debt, gross | $ 3,711 | 3,714
Southern Company Gas |  |
Debt Instrument [Line Items] |  |
Long-term debt, gross | 6,900 | 6,600
Finance lease obligations | 0 | 0
Unamortized fair value adjustment | 359 | 393
Unamortized debt premium (discount), net | (35) | (27)
Total long-term debt | 6,902 | 6,626
Less: Amount due within one year | 47 | 333
Long-Term Debt | $ 6,855 | 6,293
Southern Company Gas | Senior notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 3.96% |
Long-term debt, gross | $ 4,348 | 4,200
Southern Company Gas | First mortgage bonds |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 3.53% |
Long-term debt, gross | $ 2,100 | 1,900
Southern Company Gas | Medium-term notes |  |
Debt Instrument [Line Items] |  |
Weighted Average Interest Rate | 7.60% |
Long-term debt, gross | $ 130 | $ 160

X
- Definition Derivative Notional Amount, Receive + References No definition available. + Details
Name: | so_DerivativeNotionalAmountReceive
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value gain (Loss). + References No definition available. + Details
Name: | so_FairValueGainLoss
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition 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. + References No definition available. + Details
Name: | so_LongTermDebtandFinanceLeaseObligationNet
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Unamortized Fair Value Adjustment of Long-term Debt + References No definition available. + Details
Name: | so_UnamortizedFairValueAdjustmentofLongtermDebt
Namespace Prefix: | so_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031897-161870 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
Name: | us-gaap_DebtInstrumentCarryingAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, after accumulated amortization, of debt discount (premium). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28567-108399 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28541-108399 Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1D -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495340-112611 Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 + Details
Name: | us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Weighted average interest rate of debt outstanding. + References No definition available. + Details
Name: | us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Present value of lessee's discounted obligation for lease payments from finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918701-209980 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977 + Details
Name: | us-gaap_FinanceLeaseLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt and lease obligation, classified as noncurrent. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebtAndCapitalLeaseObligations
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of long-term debt and lease obligation, classified as current. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.20) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LongTermDebtAndCapitalLeaseObligationsCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_UnamortizedDebtIssuanceExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_JuniorSubordinatedDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=so_FederalFinancingBankLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=so_PollutionControlRevenueBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=so_FirstMortgageBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_MediumTermNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=so_OtherLongTermDebtMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=so_OtherRevenueBondsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=so_AffiliatedTrustsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=so_AlabamaPowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=so_GeorgiaPowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=so_MississippiPowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=so_SouthernPowerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=so_SouthernCompanyGasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |