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Financing (Tables) | 9 Months Ended
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Sep. 30, 2025
Debt Disclosure [Abstract] |
Schedule of Credit Arrangements | At September 30, 2025, committed credit arrangements with banks were as follows:
|  | Expires |  |  |  |  |  |  |  |
Company |  | 2026 | 2027 |  | 2029 | 2030 |  | Total |  | Unused |  |  |  |  |  |  |  | Expires within One Year
|  | (in millions)
Southern Company parent(a) |  | $ | — |  | $ | 500 |  |  | $ | — |  | $ | 2,500 |  |  | $ | 3,000 |  |  | $ | 2,999 |  |  |  |  |  |  |  |  | $ | — |
Alabama Power(b) |  | 15 |  | — |  |  | 650 |  | 700 |  |  | 1,365 |  |  | 1,365 |  |  |  |  |  |  |  |  | — |
Georgia Power(c) |  | — |  | — |  |  | — |  | 2,050 |  |  | 2,050 |  |  | 2,042 |  |  |  |  |  |  |  |  | — |
Mississippi Power(a) |  | — |  | 125 |  |  | — |  | 150 |  |  | 275 |  |  | 275 |  |  |  |  |  |  |  |  | — |
Southern Power(a)(d) |  | — |  | — |  |  | — |  | 600 |  |  | 600 |  |  | 600 |  |  |  |  |  |  |  |  | — |
Southern Company Gas(e) |  | — |  | — |  |  | — |  | 1,600 |  |  | 1,600 |  |  | 1,598 |  |  |  |  |  |  |  |  | — |
SEGCO |  | 30 |  | — |  |  | — |  | — |  |  | 30 |  |  | 30 |  |  |  |  |  |  |  |  | 30 |
Southern Company |  | $ | 45 |  | $ | 625 |  |  | $ | 650 |  | $ | 7,600 |  |  | $ | 8,920 |  |  | $ | 8,909 |  |  |  |  |  |  |  |  | $ | 30 |
(a)Arrangement expiring in 2030 represents a $3.25 billion combined arrangement for Southern Company, Mississippi Power, and Southern Power allowing for flexible sublimits. Pursuant to the combined facility, the allocations among Southern Company, Southern Power, and Mississippi Power may be adjusted. (b)Includes $15 million expiring in 2026 at Alabama Property Company, a wholly-owned subsidiary of Alabama Power, of which $15 million was unused at September 30, 2025. Alabama Power is not party to this arrangement. (c)Georgia Power had $26 million of letters of credit outstanding under an uncommitted letter of credit facility at September 30, 2025. (d)Does not include Southern Power Company's $75 million and $100 million continuing letter of credit facilities for standby letters of credit, expiring in 2027 and 2028, respectively, of which $17 million and $4 million, respectively, was unused at September 30, 2025. In addition, Southern Power Company had $23 million of letters of credit outstanding under an uncommitted letter of credit facility at September 30, 2025. Southern Power's subsidiaries are not parties to its bank credit arrangements or letter of credit facilities. (e)Southern Company Gas, as the parent entity, guarantees the obligations of Southern Company Gas Capital, which is the borrower of $800 million of the credit arrangement expiring in 2030. Southern Company Gas' committed credit arrangement expiring in 2030 also includes $800 million for which Nicor Gas is the borrower and which is restricted for working capital needs of Nicor Gas. Pursuant to the multi-year credit arrangement expiring in 2030, the allocations between Southern Company Gas Capital and Nicor Gas may be adjusted.
Schedule of Forward Contracts Indexed to Issuer's Equity | The table below reflects shares of Southern Company common stock sold under separate forward sale contracts with forward purchasers during the nine months ended September 30, 2025.
Shares Sold | Initial Forward Price per Share | To be Settled On or Before
292,694(a) | $83.3293 | December 31, 2025
563,386 | $87.9027 | December 31, 2025
1,000,000 | $88.7502 | June 30, 2026
1,000,000 | $88.7739 | June 30, 2026
1,000,000 | $91.2856 | June 30, 2026
1,000,000 | $89.1444 | June 30, 2026
1,000,000 | $88.8490 | June 30, 2026
1,000,000 | $88.8903 | June 30, 2026
1,000,000 | $90.9196 | June 30, 2026
1,255,000 | $91.0566 | June 30, 2026
1,324,942 | $88.7048 | December 31, 2026
2,277,113 | $88.3227 | December 31, 2026
3,130,641 | $88.2823 | December 31, 2026
3,255,866 | $89.4692 | December 31, 2026
3,850,000 | $90.6617 | December 31, 2026
2,470,306 | $94.5394 | June 30, 2027
2,314,487 | $92.7805 | June 30, 2027
1,590,200 | $93.4524 | June 30, 2027
4,000,000 | $90.8141 | June 30, 2027
2,346,903 | $91.1610 | June 30, 2027
2,876,034 | $92.2437 | June 30, 2027
2,642,878(b) | $93.4521(b) | June 30, 2027
(a)The total number of shares sold under this forward sale contract is 436,614, of which the first 143,920 shares were sold in December 2024. (b)The total number of shares sold under this forward sale contract is 3,015,668, of which the remaining 372,790 shares were sold subsequent to September 30, 2025. The initial forward price was determined after the completion of sales by the forward seller in October 2025.
Schedule of Shares Used to Compute Diluted Earnings Per Share | Shares used to compute diluted EPS were as follows:
| Three Months Ended September 30, | Nine Months Ended September 30,
| 2025 | 2024 | 2025 | 2024
| (in millions)
As reported shares | 1,102 |  | 1,097 |  | 1,101 |  | 1,096 |
Effect of stock-based compensation | 6 |  | 6 |  | 6 |  | 6 |
Effect of convertible senior notes | 1 |  | — |  | 1 |  | — |
Effect of forward sale contracts | 1 |  | — |  | — |  | — |
Diluted shares | 1,110 |  | 1,103 |  | 1,108 |  | 1,102 |

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- Definition Tabular disclosure of freestanding forward contracts issued by an entity that are indexed to, and potentially settled in an entity's own stock. The disclosure may include, but not be limited to: (i) the forward rate and the number of shares to which the contract is indexed, (ii) the settlement date or dates of the contract, (iii) the issuer's accounting for the contract, (iv) settlement alternatives (if applicable) including who controls the settlement alternatives and the maximum number of shares that could be required to be issued to net share settle the contract (if applicable), (v) the fact that a potentially infinite number of shares may be required to be issued to settle the contract, if a contract does not have a stated fixed or determinable maximum number of shares, and (vi) the contract's current fair value for each settlement alternative and how changes in the price of the issuer's equity instruments affect those settlement amounts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 815 -SubTopic 40 -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480237/815-40-50-5 + Details
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- Definition Tabular disclosure of short-term or long-term contractual arrangements with lenders, including letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(22)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(19)(b)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 + Details
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