XML 224 R180.htm IDEA: XBRL DOCUMENT
v3.22.0.1

LEASES - Other Information (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Cash paid for amounts included in the measurements of lease obligations: |  |  |
Operating cash flows from operating leases | $ 308 | $ 310 | $ 323
Operating cash flows from finance leases | 9 | 9 | 10
Financing cash flows from finance leases | 17 | 22 | 32
ROU assets obtained in exchange for new operating lease obligations | 64 | 227 | 118
ROU assets obtained in exchange for new finance lease obligations | $ 3 | $ 10 | 35
Weighted-average remaining lease term in years: |  |  |
Operating leases | 15 years 10 months 24 days | 14 years 6 months |
Finance leases | 18 years | 18 years 2 months 12 days |
Weighted-average discount rate: |  |  |
Operating leases | 4.41% | 4.44% |
Finance leases | 4.82% | 4.79% |
Alabama Power |  |  |
Cash paid for amounts included in the measurements of lease obligations: |  |  |
Operating cash flows from operating leases | $ 58 | $ 55 | 54
Operating cash flows from finance leases | 0 | 0 | 0
Financing cash flows from finance leases | 1 | 1 | 1
ROU assets obtained in exchange for new operating lease obligations | 3 | 63 | 7
ROU assets obtained in exchange for new finance lease obligations | $ 0 | $ 2 | 2
Weighted-average remaining lease term in years: |  |  |
Operating leases | 9 years 1 month 6 days | 7 years 9 months 18 days |
Finance leases | 8 years 8 months 12 days | 9 years 8 months 12 days |
Weighted-average discount rate: |  |  |
Operating leases | 4.37% | 4.14% |
Finance leases | 3.09% | 3.20% |
Georgia Power |  |  |
Cash paid for amounts included in the measurements of lease obligations: |  |  |
Operating cash flows from operating leases | $ 211 | $ 215 | 210
Operating cash flows from finance leases | 17 | 18 | 19
Financing cash flows from finance leases | 9 | 11 | 13
ROU assets obtained in exchange for new operating lease obligations | 9 | 32 | 21
ROU assets obtained in exchange for new finance lease obligations | $ 0 | $ 0 | 24
Weighted-average remaining lease term in years: |  |  |
Operating leases | 8 years 8 months 12 days | 9 years 4 months 24 days |
Finance leases | 8 years 6 months | 9 years 6 months |
Weighted-average discount rate: |  |  |
Operating leases | 4.45% | 4.37% |
Finance leases | 10.81% | 10.81% |
Mississippi Power |  |  |
Cash paid for amounts included in the measurements of lease obligations: |  |  |
Operating cash flows from operating leases | $ 2 | $ 3 | 3
Operating cash flows from finance leases | 1 | 0 | 0
Financing cash flows from finance leases | 1 | 0 | 0
ROU assets obtained in exchange for new operating lease obligations | 0 | 0 | 0
ROU assets obtained in exchange for new finance lease obligations | $ 0 | $ 0 | 0
Weighted-average remaining lease term in years: |  |  |
Operating leases | 6 years 1 month 6 days | 6 years 6 months |
Finance leases | 13 years 10 months 24 days | 14 years 10 months 24 days |
Weighted-average discount rate: |  |  |
Operating leases | 2.74% | 3.26% |
Finance leases | 2.74% | 2.74% |
Southern Power |  |  |
Cash paid for amounts included in the measurements of lease obligations: |  |  |
Operating cash flows from operating leases | $ 28 | $ 28 | 27
Operating cash flows from finance leases | 0 | 0 | 0
Financing cash flows from finance leases | 0 | 0 | 0
ROU assets obtained in exchange for new operating lease obligations | 72 | 51 | 2
ROU assets obtained in exchange for new finance lease obligations | $ 0 | $ 0 | 0
Weighted-average remaining lease term in years: |  |  |
Operating leases | 32 years 9 months 18 days | 32 years 1 month 6 days |
Weighted-average discount rate: |  |  |
Operating leases | 5.20% | 5.45% |
Southern Company Gas |  |  |
Cash paid for amounts included in the measurements of lease obligations: |  |  |
Operating cash flows from operating leases | $ 19 | $ 18 | 18
Operating cash flows from finance leases | 0 | 0 | 0
Financing cash flows from finance leases | 0 | 0 | 0
ROU assets obtained in exchange for new operating lease obligations | 7 | 4 | 19
ROU assets obtained in exchange for new finance lease obligations | $ 0 | $ 0 | $ 0
Weighted-average remaining lease term in years: |  |  |
Operating leases | 10 years 6 months | 9 years 9 months 18 days |
Weighted-average discount rate: |  |  |
Operating leases | 3.61% | 3.67% |

X
- Definition Cash Flow, Lessee [Abstract] + References No definition available. + Details
Name: | so_CashFlowLesseeAbstract
Namespace Prefix: | so_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lease, Weighted Average Discount Rate, Percent [Abstract] + References No definition available. + Details
Name: | so_LeaseWeightedAverageDiscountRatePercentAbstract
Namespace Prefix: | so_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Lease, Weighted Average Remaining Lease Term [Abstract] + References No definition available. + Details
Name: | so_LeaseWeightedAverageRemainingLeaseTermAbstract
Namespace Prefix: | so_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of interest paid on finance lease liability. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(1) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918643-209977 + Details
Name: | us-gaap_FinanceLeaseInterestPaymentOnLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of cash outflow for principal payment on finance lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918643-209977 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(1) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 + Details
Name: | us-gaap_FinanceLeasePrincipalPayments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Weighted average discount rate for finance lease calculated at point in time. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(4) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971 + Details
Name: | us-gaap_FinanceLeaseWeightedAverageDiscountRatePercent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average remaining lease term for finance lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(3) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971 + Details
Name: | us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of cash outflow from operating lease, excluding payments to bring another asset to condition and location necessary for its intended use. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 45 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918643-209977 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(1) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 + Details
Name: | us-gaap_OperatingLeasePayments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Weighted average discount rate for operating lease calculated at point in time. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(4) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971 + Details
Name: | us-gaap_OperatingLeaseWeightedAverageDiscountRatePercent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Weighted average remaining lease term for operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(3) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 + Details
Name: | us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of increase in right-of-use asset obtained in exchange for finance lease liability. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(2) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 + Details
Name: | us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of increase in right-of-use asset obtained in exchange for operating lease liability. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(2) -URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980 + Details
Name: | us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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: |