XML 130 R99.htm IDEA: XBRL DOCUMENT
v3.25.3

Financing - Equity Distribution Agreement (Details) - $ / shares | 1 Months Ended | 7 Months Ended | 9 Months Ended | 11 Months Ended
--- | --- | --- | --- | ---
Oct. 30, 2025 | Oct. 29, 2025 | Dec. 31, 2024 | Jun. 30, 2025 | Sep. 30, 2025 | Sep. 30, 2025
Forward Sale Contract 1 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  | 143,920 |  | 292,694 |
Forward price (in dollars per share) |  |  |  |  | $ 83.3293 |
Number of shares authorized (in shares) |  |  |  | 436,614 |  |
Forward Sale Contract 2 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 563,386 |
Forward price (in dollars per share) |  |  |  |  | $ 87.9027 |
Forward Sale Contract 3 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,000,000 |
Forward price (in dollars per share) |  |  |  |  | $ 88.7502 |
Forward Sale Contract 4 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,000,000 |
Forward price (in dollars per share) |  |  |  |  | $ 88.7739 |
Forward Sale Contract 5 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,000,000 |
Forward price (in dollars per share) |  |  |  |  | $ 91.2856 |
Forward Sale Contract 6 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,000,000 |
Forward price (in dollars per share) |  |  |  |  | $ 89.1444 |
Forward Sale Contract 7 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,000,000 |
Forward price (in dollars per share) |  |  |  |  | $ 88.8490 |
Forward Sale Contract 8 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,000,000 |
Forward price (in dollars per share) |  |  |  |  | $ 88.8903 |
Forward Sale Contract 9 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,000,000 |
Forward price (in dollars per share) |  |  |  |  | $ 90.9196 |
Forward Sale Contract 10 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,255,000 |
Forward price (in dollars per share) |  |  |  |  | $ 91.0566 |
Forward Sale Contract 11 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,324,942 |
Forward price (in dollars per share) |  |  |  |  | $ 88.7048 |
Forward Sale Contract 12 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 2,277,113 |
Forward price (in dollars per share) |  |  |  |  | $ 88.3227 |
Forward Sale Contract 13 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 3,130,641 |
Forward price (in dollars per share) |  |  |  |  | $ 88.2823 |
Forward Sale Contract 14 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 3,255,866 |
Forward price (in dollars per share) |  |  |  |  | $ 89.4692 |
Forward Sale Contract 15 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 3,850,000 |
Forward price (in dollars per share) |  |  |  |  | $ 90.6617 |
Forward Sale Contract 16 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 2,470,306 |
Forward price (in dollars per share) |  |  |  |  | $ 94.5394 |
Forward Sale Contract 17 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 2,314,487 |
Forward price (in dollars per share) |  |  |  |  | $ 92.7805 |
Forward Sale Contract 18 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 1,590,200 |
Forward price (in dollars per share) |  |  |  |  | $ 93.4524 |
Forward Sale Contract 19 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 4,000,000 |
Forward price (in dollars per share) |  |  |  |  | $ 90.8141 |
Forward Sale Contract 20 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 2,346,903 |
Forward price (in dollars per share) |  |  |  |  | $ 91.1610 |
Forward Sale Contract 21 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 2,876,034 |
Forward price (in dollars per share) |  |  |  |  | $ 92.2437 |
Forward Sale Contract 22 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  | 2,642,878 |
Forward price (in dollars per share) |  |  |  |  | $ 93.4521 |
Number of shares authorized (in shares) |  |  |  |  | 3,015,668 |
Subsequent Event | Forward Sale Contract 22 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  | 372,790 |  |  |  |
Subsequent Event | Forward Sale Contract 23 |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) | 911,448 |  |  |  |  |
Forward price (in dollars per share) |  | $ 94.2411 |  |  |  |
Private Placement |  |  |  |  |  |
Line of Credit Facility [Line Items] |  |  |  |  |  |
Common stock issued to settle purchase contracts (in shares) |  |  |  |  |  | 43,334,370
Number of shares authorized (in shares) |  |  |  |  |  | 43,707,160

X
- Definition The per share price of the Company's stock at which the contract holder of the freestanding contract has the right to purchase or sell the Company's stock at a future date. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 40 -Section 50 -Paragraph 5 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480237/815-40-50-5 + Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityForwardRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum number of shares that could be issued to settle forward contract indexed to equity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 815 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (b)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480237/815-40-50-5 + Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityShares
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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 Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(f)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-6 Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 470 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481544/470-10-50-6 + Details
Name: | us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of shares issued or sold by the subsidiary or equity method investee per stock transaction. + References No definition available. + Details
Name: | us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract4Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract5Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract6Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract7Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract8Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract9Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract10Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract11Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract12Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract13Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract14Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract15Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract16Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract17Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract18Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract19Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract20Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract21Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract22Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ForwardContractIndexedToIssuersEquityTypeAxis=so_ForwardSaleContract23Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=us-gaap_PrivatePlacementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |