SOUTHERN CO, 10-Q filed on 4/30/2026
Quarterly Report
v3.26.1
Cover Page
 3 Months Ended
Mar. 31, 2026
shares
Document Information [Line Items]  
Document Type 10-Q
Document Quarterly Report true
Document Period End Date Mar. 31, 2026
Document Transition Report false
Entity File Number 1-3526
Entity Registrant Name The Southern Company
Entity Tax Identification Number 58-0690070
Entity Incorporation, State or Country Code DE
Entity Address, Address Line One 30 Ivan Allen Jr. Boulevard, N.W.
Entity Address, City or Town Atlanta
Entity Address, State or Province GA
Entity Address, Postal Zip Code 30308
City Area Code 404
Local Phone Number 506-5000
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Filer Category Large Accelerated Filer
Entity Small Business false
Entity Emerging Growth Company false
Entity Shell Company false
Entity Common Stock, Shares Outstanding (in shares) 1,127,301,098
Entity Central Index Key 0000092122
Amendment Flag false
Document Fiscal Year Focus 2026
Document Fiscal Period Focus Q1
Current Fiscal Year End Date --12-31
Common Stock, par value $5 per share  
Document Information [Line Items]  
Title of 12(b) Security Common Stock, par value $5 per share
Trading Symbol SO
Security Exchange Name NYSE
Series 2017B 5.25% Junior Subordinated Notes due 2077  
Document Information [Line Items]  
Title of 12(b) Security Series 2017B 5.25% Junior Subordinated Notes due 2077
Trading Symbol SOJC
Security Exchange Name NYSE
Series 2020A 4.95% Junior Subordinated Notes due 2080  
Document Information [Line Items]  
Title of 12(b) Security Series 2020A 4.95% Junior Subordinated Notes due 2080
Trading Symbol SOJD
Security Exchange Name NYSE
Series 2020C 4.20% Junior Subordinated Notes due 2060  
Document Information [Line Items]  
Title of 12(b) Security Series 2020C 4.20% Junior Subordinated Notes due 2060
Trading Symbol SOJE
Security Exchange Name NYSE
Series 2021B 1.875% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2081  
Document Information [Line Items]  
Title of 12(b) Security Series 2021B 1.875% Fixed-to-Fixed Reset Rate Junior Subordinated Notes due 2081
Trading Symbol SO 81
Security Exchange Name NYSE
Series 2025A 6.50% Junior Subordinated Notes due 2085  
Document Information [Line Items]  
Title of 12(b) Security Series 2025A 6.50% Junior Subordinated Notes due 2085
Trading Symbol SOJF
Security Exchange Name NYSE
2025 Series A Corporate Units  
Document Information [Line Items]  
Title of 12(b) Security 2025 Series A Corporate Units
Trading Symbol SOMN
Security Exchange Name NYSE
ALABAMA POWER CO  
Document Information [Line Items]  
Entity File Number 1-3164
Entity Registrant Name Alabama Power Company
Entity Tax Identification Number 63-0004250
Entity Incorporation, State or Country Code AL
Entity Address, Address Line One 600 North 18th Street
Entity Address, City or Town Birmingham
Entity Address, State or Province AL
Entity Address, Postal Zip Code 35203
City Area Code 205
Local Phone Number 257-1000
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Filer Category Non-accelerated Filer
Entity Small Business false
Entity Emerging Growth Company false
Entity Shell Company false
Entity Common Stock, Shares Outstanding (in shares) 30,537,500
Entity Central Index Key 0000003153
GEORGIA POWER CO  
Document Information [Line Items]  
Entity File Number 1-6468
Entity Registrant Name Georgia Power Company
Entity Tax Identification Number 58-0257110
Entity Incorporation, State or Country Code GA
Entity Address, Address Line One 241 Ralph McGill Boulevard, N.E.
Entity Address, City or Town Atlanta
Entity Address, State or Province GA
Entity Address, Postal Zip Code 30308
City Area Code 404
Local Phone Number 506-6526
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Filer Category Non-accelerated Filer
Entity Small Business false
Entity Emerging Growth Company false
Entity Shell Company false
Entity Common Stock, Shares Outstanding (in shares) 9,261,500
Entity Central Index Key 0000041091
GEORGIA POWER CO | Series 2017A 5.00% Junior Subordinated Notes due 2077  
Document Information [Line Items]  
Title of 12(b) Security Series 2017A 5.00% Junior Subordinated Notes due 2077
Trading Symbol GPJA
Security Exchange Name NYSE
MISSISSIPPI POWER CO  
Document Information [Line Items]  
Entity File Number 001-11229
Entity Registrant Name Mississippi Power Company
Entity Tax Identification Number 64-0205820
Entity Incorporation, State or Country Code MS
Entity Address, Address Line One 2992 West Beach Boulevard
Entity Address, City or Town Gulfport
Entity Address, State or Province MS
Entity Address, Postal Zip Code 39501
City Area Code 228
Local Phone Number 864-1211
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Filer Category Non-accelerated Filer
Entity Small Business false
Entity Emerging Growth Company false
Entity Shell Company false
Entity Common Stock, Shares Outstanding (in shares) 1,121,000
Entity Central Index Key 0000066904
SOUTHERN POWER CO  
Document Information [Line Items]  
Entity File Number 001-37803
Entity Registrant Name Southern Power Company
Entity Tax Identification Number 58-2598670
Entity Incorporation, State or Country Code DE
Entity Address, Address Line One 30 Ivan Allen Jr. Boulevard, N.W.
Entity Address, City or Town Atlanta
Entity Address, State or Province GA
Entity Address, Postal Zip Code 30308
City Area Code 404
Local Phone Number 506-5000
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Filer Category Non-accelerated Filer
Entity Small Business false
Entity Emerging Growth Company false
Entity Shell Company false
Entity Common Stock, Shares Outstanding (in shares) 1,000
Entity Central Index Key 0001160661
SOUTHERN POWER CO | Series 2016B 1.850% Senior Notes due 2026  
Document Information [Line Items]  
Title of 12(b) Security Series 2016B 1.850% Senior Notes due 2026
Trading Symbol SO/26A
Security Exchange Name NYSE
SOUTHERN Co GAS  
Document Information [Line Items]  
Entity File Number 1-14174
Entity Registrant Name Southern Company Gas
Entity Tax Identification Number 58-2210952
Entity Incorporation, State or Country Code GA
Entity Address, Address Line One Ten Peachtree Place, N.E.
Entity Address, City or Town Atlanta
Entity Address, State or Province GA
Entity Address, Postal Zip Code 30309
City Area Code 404
Local Phone Number 584-4000
Entity Current Reporting Status Yes
Entity Interactive Data Current Yes
Entity Filer Category Non-accelerated Filer
Entity Small Business false
Entity Emerging Growth Company false
Entity Shell Company false
Entity Common Stock, Shares Outstanding (in shares) 100
Entity Central Index Key 0001004155
v3.26.1
Condensed Consolidated Statements of Income (Unaudited) - Southern - USD ($)
shares in Millions, $ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Revenues:    
Total operating revenues $ 8,397 $ 7,775
Operating Expenses:    
Other operations and maintenance 1,653 1,619
Depreciation and amortization 1,420 1,286
Taxes other than income taxes 464 445
Total operating expenses 6,379 5,765
Operating Income 2,018 2,010
Other Income and (Expense):    
Allowance for equity funds used during construction 121 73
Earnings from equity method investments 50 32
Interest expense, net of amounts capitalized (778) (714)
Other income (expense), net 155 149
Total other income and (expense) (452) (460)
Earnings Before Income Taxes 1,566 1,550
Income taxes 228 280
Consolidated Net Income 1,338 1,270
Net loss attributable to noncontrolling interests (18) (64)
Consolidated Net Income Attributable to Southern Company $ 1,356 $ 1,334
Earnings per share -    
Basic (in dollars per share) $ 1.21 $ 1.21
Diluted (in dollars per share) $ 1.20 $ 1.21
Average number of shares of common stock outstanding — (in millions)    
Basic (in shares) 1,124 1,100
Diluted (in shares) 1,128 1,105
Retail electric revenues    
Operating Revenues:    
Total operating revenues $ 4,640 $ 4,601
Wholesale electric revenues    
Operating Revenues:    
Total operating revenues 965 744
Other electric revenues    
Operating Revenues:    
Total operating revenues 265 242
Natural Gas    
Operating Revenues:    
Total operating revenues 2,191 1,839
Other revenues    
Operating Revenues:    
Total operating revenues 336 349
Operating Expenses:    
Total cost of sales 181 199
Fuel    
Operating Expenses:    
Total cost of sales 1,491 1,292
Purchased power    
Operating Expenses:    
Total cost of sales 244 250
Natural gas    
Operating Expenses:    
Total cost of sales 926 674
Alternative revenue programs    
Operating Revenues:    
Total operating revenues $ (2) $ (19)
v3.26.1
Condensed Consolidated Statements of Income (Unaudited) - Southern (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Total operating revenues $ 8,397 $ 7,775
Alternative revenue programs    
Total operating revenues $ (2) $ (19)
v3.26.1
Condensed Consolidated Statements of Comprehensive Income (Unaudited) - Southern - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Statement of Comprehensive Income [Abstract]    
Consolidated Net Income $ 1,338 $ 1,270
Qualifying hedges:    
Changes in fair value, net of tax (3) 14
Reclassification adjustment for amounts included in net income, net of tax 4 (12)
Pension and other postretirement benefit plans:    
Benefit plan net gain (loss), net of tax 1 1
Total other comprehensive income 2 3
Comprehensive Income 1,340 1,273
Comprehensive loss attributable to noncontrolling interests (18) (64)
Consolidated Comprehensive Income Attributable to Company $ 1,358 $ 1,337
v3.26.1
Condensed Consolidated Statements of Comprehensive Income (Unaudited) - Southern (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Statement of Comprehensive Income [Abstract]    
Changes in fair value, tax $ (1) $ 5
Qualifying hedges, reclassification adjustment, tax 1 (4)
Benefit plan net gain (loss), tax $ 0 $ 0
v3.26.1
Condensed Consolidated Statements of Cash Flows (Unaudited) - Southern - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Activities:    
Consolidated Net Income $ 1,338 $ 1,270
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 1,580 1,411
Deferred income taxes 168 351
Allowance for equity funds used during construction (121) (73)
Pension, postretirement, and other employee benefits (149) (149)
Settlement of asset retirement obligations (133) (134)
Stock based compensation expense 97 90
Storm damage cost recovery – long-term (93) (173)
Other, net (25) (1)
Changes in certain current assets and liabilities —    
Receivables 124 7
Retail fuel cost under recovery 63 71
Prepayments (98) (120)
Materials and supplies (85) 11
Natural gas for sale, net of temporary LIFO liquidation 355 365
Other current assets (27) 66
Accounts payable (555) (394)
Accrued taxes (408) (418)
Accrued compensation (599) (537)
Accrued interest (180) (82)
Customer refunds 5 (95)
Natural gas cost over recovery (27) (179)
Other current liabilities (4) (37)
Net cash provided from operating activities 1,226 1,250
Investing Activities:    
Property additions (2,944) (2,437)
Nuclear decommissioning trust fund purchases (442) (361)
Nuclear decommissioning trust fund sales 442 361
Cost of removal, net of salvage (166) (168)
Change in construction payables, net (251) (161)
Other investing activities (60) (68)
Net cash used for investing activities (3,421) (2,834)
Financing Activities:    
Increase (decrease) in notes payable, net 653  
Decrease in notes payable, net   (841)
Proceeds —    
Long-term debt 2,390 4,567
Short-term borrowings 350 0
Common stock 535 30
Redemptions and repurchases —    
Long-term debt (1,322) (35)
Short-term borrowings (50) 0
Distributions to noncontrolling interests (47) (37)
Payment of common stock dividends (776) (736)
Other financing activities (191) (133)
Net cash provided from financing activities 1,542 2,815
Net Change in Cash, Cash Equivalents, and Restricted Cash (653) 1,231
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 1,640 1,101
Cash, Cash Equivalents, and Restricted Cash at End of Period 987 2,332
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 901 756
Income taxes, net (excludes credit transfers) 0 (1)
Noncash transactions —    
Accrued property additions at end of period 1,049 940
Right-of-use assets obtained under operating leases 41 87
Right-of-use assets obtained under finance leases 2 13
Issuance of common stock under dividend reinvestment plan $ 54 $ 55
v3.26.1
Condensed Consolidated Statements of Cash Flows (Unaudited) - Southern (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Statement of Cash Flows [Abstract]    
Net cash paid for capitalized interest $ 51 $ 29
v3.26.1
Condensed Consolidated Balance Sheets (Unaudited) - Southern - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Current Assets:    
Cash and cash equivalents $ 981 $ 1,639
Receivables —    
Customer accounts 2,405 2,251
Unbilled revenues 740 931
Under recovered fuel clause revenues 299 316
Other accounts and notes 524 655
Accumulated provision for uncollectible accounts (95) (84)
Materials and supplies 2,297 2,202
Fossil fuel for generation 727 735
Natural gas for sale 145 396
Prepaid expenses 411 327
Assets from risk management activities, net of collateral 35 63
Regulatory assets – asset retirement obligations 353 353
Other regulatory assets 706 709
Other current assets 433 424
Total current assets 9,961 10,917
Property, Plant, and Equipment:    
In service 149,086 146,114
Less: Accumulated depreciation 45,186 43,483
Plant in service, net of depreciation 103,900 102,631
Other utility plant, net 0 307
Nuclear fuel, at amortized cost 920 897
Construction work in progress 11,282 10,534
Total property, plant, and equipment 116,102 114,369
Other Property and Investments:    
Goodwill 5,161 5,161
Nuclear decommissioning trusts, at fair value 2,888 2,947
Equity investments in unconsolidated subsidiaries 1,365 1,318
Other intangible assets, net of amortization 294 300
Miscellaneous property and investments 706 714
Total other property and investments 10,414 10,440
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 1,351 1,358
Deferred charges related to income taxes 1,026 948
Prepaid pension costs 3,369 3,257
Unamortized loss on reacquired debt 183 187
Deferred under recovered fuel clause revenues 210 252
Regulatory assets – asset retirement obligations, deferred 5,198 5,129
Other regulatory assets, deferred 7,683 7,427
Other deferred charges and assets 1,534 1,436
Total deferred charges and other assets 20,554 19,994
Total Assets 157,031 155,720
Current Liabilities:    
Securities due within one year 5,701 6,220
Notes payable 1,673 722
Accounts payable 2,909 3,710
Customer deposits 478 475
Accrued taxes —    
Accrued income taxes 66 22
Other accrued taxes 557 982
Accrued interest 627 807
Accrued compensation 761 1,418
Asset retirement obligations 659 662
Liabilities from risk management activities, net of collateral 134 118
Operating lease obligations 203 197
Natural gas cost over recovery 131 158
Other regulatory liabilities 228 240
Other current liabilities 1,191 1,157
Total current liabilities 15,318 16,888
Long-term Debt 67,148 65,649
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 12,381 12,133
Deferred credits related to income taxes 4,648 4,712
Accumulated deferred ITCs 2,047 2,002
Employee benefit obligations 941 980
Operating lease obligations, deferred 1,280 1,287
Asset retirement obligations, deferred 8,907 8,939
Other cost of removal obligations 2,054 2,036
Other regulatory liabilities, deferred 770 722
Other deferred credits and liabilities 1,625 1,505
Total deferred credits and other liabilities 34,653 34,316
Total Liabilities 117,119 116,853
Total Stockholders' Equity 39,912 38,867
Total Liabilities and Stockholders' Equity $ 157,031 $ 155,720
v3.26.1
Condensed Consolidated Balance Sheets (Unaudited) - Southern (Parenthetical) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Statement of Financial Position [Abstract]    
Other intangible assets, amortization $ 450 $ 444
v3.26.1
Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - Southern - USD ($)
shares in Millions, $ in Millions
Total
Common Stock
Treasury
Paid-In Capital
Retained Earnings
Accumulated Other Comprehensive Income (Loss)
Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2024   1,098          
Beginning balance (in shares) at Dec. 31, 2024     (1)        
Beginning balance at Dec. 31, 2024 $ 36,674 $ 5,446 $ (59) $ 14,149 $ 13,750 $ (78) $ 3,466
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income (loss) 1,270       1,334   (64)
Other comprehensive income 3         3  
Stock issued (in shares)   2          
Stock issued 85 $ 7   78      
Stock-based compensation 5     5      
Cash dividends (791)       (791)    
Capital contributions from noncontrolling interests 19           19
Distributions to noncontrolling interests (37)           (37)
Other (5)   $ (2) (1) (2)    
Ending balance (in shares) at Mar. 31, 2025   1,100          
Ending balance (in shares) at Mar. 31, 2025     (1)        
Ending balance at Mar. 31, 2025 37,223 $ 5,453 $ (61) 14,231 14,291 (75) 3,384
Beginning balance (in shares) at Dec. 31, 2025   1,120          
Beginning balance (in shares) at Dec. 31, 2025     (1)        
Beginning balance at Dec. 31, 2025 38,867 $ 5,554 $ (59) 15,740 14,856 (75) 2,851
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income (loss) 1,338       1,356   (18)
Other comprehensive income 2         2  
Stock issued (in shares)   8          
Stock issued 589 $ 34   555      
Stock-based compensation (9)     (9)      
Cash dividends (830)       (830)    
Capital contributions from noncontrolling interests 4           4
Distributions to noncontrolling interests (46)           (46)
Other (3)   $ (1) (1)     (1)
Ending balance (in shares) at Mar. 31, 2026   1,128          
Ending balance (in shares) at Mar. 31, 2026     (1)        
Ending balance at Mar. 31, 2026 $ 39,912 $ 5,588 $ (60) $ 16,285 $ 15,382 $ (73) $ 2,790
v3.26.1
Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - Southern (Parenthetical) - $ / shares
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Statement of Stockholders' Equity [Abstract]    
Cash dividends (in dollars per share) $ 0.74 $ 0.72
v3.26.1
Condensed Statements of Income (Unaudited) - APC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Revenues:    
Total operating revenues $ 8,397 $ 7,775
Operating Expenses:    
Other operations and maintenance 1,653 1,619
Depreciation and amortization 1,420 1,286
Taxes other than income taxes 464 445
Total operating expenses 6,379 5,765
Operating Income 2,018 2,010
Other Income and (Expense):    
Allowance for equity funds used during construction 121 73
Interest expense, net of amounts capitalized (778) (714)
Other income (expense), net 155 149
Total other income and (expense) (452) (460)
Earnings Before Income Taxes 1,566 1,550
Income taxes (benefit) 228 280
Consolidated Net Income Attributable to Southern Company 1,356 1,334
Retail revenues    
Operating Revenues:    
Total operating revenues 4,640 4,601
Other revenues    
Operating Revenues:    
Total operating revenues 336 349
Operating Expenses:    
Total cost of sales 181 199
Fuel    
Operating Expenses:    
Total cost of sales 1,491 1,292
Purchased power, non-affiliates    
Operating Expenses:    
Total cost of sales 244 250
Alabama Power    
Operating Revenues:    
Total operating revenues 2,092 2,012
Operating Expenses:    
Other operations and maintenance 393 463
Depreciation and amortization 381 370
Taxes other than income taxes 133 131
Total operating expenses 1,481 1,474
Operating Income 611 538
Other Income and (Expense):    
Allowance for equity funds used during construction 19 18
Interest expense, net of amounts capitalized (115) (108)
Other income (expense), net 39 38
Total other income and (expense) (57) (52)
Earnings Before Income Taxes 554 486
Income taxes (benefit) 129 111
Consolidated Net Income Attributable to Southern Company 425 375
Alabama Power | Retail revenues    
Operating Revenues:    
Total operating revenues 1,728 1,723
Alabama Power | Wholesale revenues, non-affiliates    
Operating Revenues:    
Total operating revenues 117 91
Alabama Power | Wholesale revenues, affiliates    
Operating Revenues:    
Total operating revenues 119 69
Alabama Power | Other revenues    
Operating Revenues:    
Total operating revenues 128 129
Alabama Power | Fuel    
Operating Expenses:    
Total cost of sales 428 386
Alabama Power | Purchased power, non-affiliates    
Operating Expenses:    
Total cost of sales 73 69
Alabama Power | Purchased power, affiliates    
Operating Expenses:    
Total cost of sales $ 73 $ 55
v3.26.1
Condensed Statements of Comprehensive Income (Unaudited) - APC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Net income $ 1,356 $ 1,334
Qualifying hedges:    
Reclassification adjustment for amounts included in net income, net of tax 4 (12)
Consolidated Comprehensive Income Attributable to Company 1,358 1,337
Alabama Power    
Net income 425 375
Qualifying hedges:    
Reclassification adjustment for amounts included in net income, net of tax 0 1
Total other comprehensive income (loss) 0 1
Consolidated Comprehensive Income Attributable to Company $ 425 $ 376
v3.26.1
Condensed Statements of Comprehensive Income (Unaudited) - APC (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Qualifying hedges, reclassification adjustment, tax $ 1 $ (4)
Alabama Power    
Qualifying hedges, reclassification adjustment, tax $ 0 $ 0
v3.26.1
Condensed Statements of Cash Flows (Unaudited) - APC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Activities:    
Net income $ 1,356 $ 1,334
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 1,580 1,411
Deferred income taxes 168 351
Pension, postretirement, and other employee benefits (149) (149)
Settlement of asset retirement obligations (133) (134)
Other, net (25) (1)
Changes in certain current assets and liabilities —    
Receivables 124 7
Prepayments (98) (120)
Other current assets (27) 66
Accounts payable (555) (394)
Accrued taxes (408) (418)
Accrued compensation (599) (537)
Customer refunds 5 (95)
Other current liabilities (4) (37)
Net cash provided from operating activities 1,226 1,250
Investing Activities:    
Property additions (2,944) (2,437)
Nuclear decommissioning trust fund purchases (442) (361)
Nuclear decommissioning trust fund sales 442 361
Cost of removal, net of salvage (166) (168)
Change in construction payables, net (251) (161)
Other investing activities (60) (68)
Net cash used for investing activities (3,421) (2,834)
Financing Activities:    
Increase (decrease) in notes payable, net 653  
Increase in notes payable, net   (841)
Proceeds —    
Payment of common stock dividends (776) (736)
Other financing activities (191) (133)
Net cash provided from financing activities 1,542 2,815
Net Change in Cash, Cash Equivalents, and Restricted Cash (653) 1,231
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 1,640 1,101
Cash, Cash Equivalents, and Restricted Cash at End of Period 987 2,332
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 901 756
Noncash transactions —    
Accrued property additions at end of period 1,049 940
Alabama Power    
Operating Activities:    
Net income 425 375
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 431 404
Deferred income taxes 62 81
Pension, postretirement, and other employee benefits (59) (52)
Settlement of asset retirement obligations (57) (61)
Other, net (63) (30)
Changes in certain current assets and liabilities —    
Receivables 101 41
Prepayments (84) (103)
Other current assets (25) 25
Accounts payable (356) (244)
Accrued taxes 105 116
Accrued compensation (135) (112)
Customer refunds 3 (95)
Other current liabilities (47) (118)
Net cash provided from operating activities 301 227
Investing Activities:    
Property additions (470) (512)
Nuclear decommissioning trust fund purchases (125) (115)
Nuclear decommissioning trust fund sales 125 115
Cost of removal, net of salvage (39) (41)
Change in construction payables, net 14 (29)
Other investing activities (14) (9)
Net cash used for investing activities (509) (591)
Financing Activities:    
Increase (decrease) in notes payable, net 30  
Increase in notes payable, net   0
Proceeds —    
Senior notes 0 500
Other long-term debt 0 2
Redemptions — Other long-term debt (45) 0
Capital contributions from parent company 225 525
Payment of common stock dividends (301) (305)
Other financing activities 8 (4)
Net cash provided from financing activities (83) 718
Net Change in Cash, Cash Equivalents, and Restricted Cash (291) 354
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 566 585
Cash, Cash Equivalents, and Restricted Cash at End of Period 275 939
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 153 139
Noncash transactions —    
Accrued property additions at end of period 115 119
Right-of-use assets obtained under operating leases $ 9 $ 1
v3.26.1
Condensed Statements of Cash Flows (Unaudited) - APC (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Net cash paid for capitalized interest $ 51 $ 29
Alabama Power    
Net cash paid for capitalized interest $ 6 $ 5
v3.26.1
Condensed Balance Sheets (Unaudited) - APC - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Current Assets:    
Cash and cash equivalents $ 981 $ 1,639
Receivables —    
Customer accounts and affiliated 2,405 2,251
Unbilled revenues 740 931
Other accounts and notes 524 655
Accumulated provision for uncollectible accounts (95) (84)
Fossil fuel stock 727 735
Materials and supplies 2,297 2,202
Prepaid expenses 411 327
Other regulatory assets 706 709
Other current assets 433 424
Total current assets 9,961 10,917
Property, Plant, and Equipment:    
In service 149,086 146,114
Less: Accumulated depreciation 45,186 43,483
Plant in service, net of depreciation 103,900 102,631
Other utility plant, net 0 307
Nuclear fuel, at amortized cost 920 897
Construction work in progress 11,282 10,534
Total property, plant, and equipment 116,102 114,369
Other Property and Investments:    
Nuclear decommissioning trusts, at fair value 2,888 2,947
Equity investments in unconsolidated subsidiaries 1,365 1,318
Miscellaneous property and investments 706 714
Total other property and investments 10,414 10,440
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 1,351 1,358
Deferred charges related to income taxes 1,026 948
Regulatory assets – asset retirement obligations 5,198 5,129
Other regulatory assets, deferred 7,683 7,427
Other deferred charges and assets 1,534 1,436
Total deferred charges and other assets 20,554 19,994
Total Assets 157,031 155,720
Current Liabilities:    
Securities due within one year 5,701 6,220
Notes payable 1,673 722
Accounts payable —    
Customer deposits 478 475
Accrued interest 627 807
Accrued compensation 761 1,418
Asset retirement obligations 659 662
Other regulatory liabilities 228 240
Other current liabilities 1,191 1,157
Total current liabilities 15,318 16,888
Long-term Debt 67,148 65,649
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 12,381 12,133
Deferred credits related to income taxes 4,648 4,712
Accumulated deferred ITCs 2,047 2,002
Employee benefit obligations 941 980
Operating lease obligations 1,280 1,287
Asset retirement obligations, deferred 8,907 8,939
Other regulatory liabilities, deferred 770 722
Other deferred credits and liabilities 1,625 1,505
Total deferred credits and other liabilities 34,653 34,316
Total Liabilities 117,119 116,853
Total Liabilities and Stockholders' Equity 157,031 155,720
Alabama Power    
Current Assets:    
Cash and cash equivalents 275 566
Receivables —    
Unbilled revenues 158 189
Other accounts and notes 54 113
Accumulated provision for uncollectible accounts (25) (23)
Fossil fuel stock 289 303
Materials and supplies 745 732
Prepaid expenses 170 86
Other regulatory assets 353 344
Other current assets 85 80
Total current assets 2,706 2,986
Property, Plant, and Equipment:    
In service 40,185 38,915
Less: Accumulated depreciation 13,754 12,816
Plant in service, net of depreciation 26,431 26,099
Other utility plant, net 0 307
Nuclear fuel, at amortized cost 285 290
Construction work in progress 1,550 1,441
Total property, plant, and equipment 28,266 28,137
Other Property and Investments:    
Nuclear decommissioning trusts, at fair value 1,510 1,542
Equity investments in unconsolidated subsidiaries 49 48
Miscellaneous property and investments 123 123
Total other property and investments 1,682 1,713
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 91 86
Deferred charges related to income taxes 262 261
Prepaid pension and other postretirement benefit costs 1,046 1,016
Regulatory assets – asset retirement obligations 1,572 1,518
Other regulatory assets, deferred 2,070 1,982
Other deferred charges and assets 456 425
Total deferred charges and other assets 5,497 5,288
Total Assets 38,151 38,124
Current Liabilities:    
Securities due within one year 462 625
Notes payable 30 0
Accounts payable —    
Customer deposits 114 113
Accrued taxes 211 105
Accrued interest 96 134
Accrued compensation 153 275
Asset retirement obligations 258 256
Other regulatory liabilities 70 89
Other current liabilities 131 135
Total current liabilities 2,076 2,602
Long-term Debt 11,507 11,388
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 4,313 4,209
Deferred credits related to income taxes 1,560 1,585
Accumulated deferred ITCs 113 115
Employee benefit obligations 149 152
Operating lease obligations 81 78
Asset retirement obligations, deferred 3,404 3,423
Other regulatory liabilities, deferred 239 252
Other deferred credits and liabilities 365 326
Total deferred credits and other liabilities 10,224 10,140
Total Liabilities 23,807 24,130
Total common stockholders' equity 14,344 13,994
Total Liabilities and Stockholders' Equity 38,151 38,124
Alabama Power | Nonrelated Party    
Receivables —    
Customer accounts and affiliated 460 470
Accounts payable —    
Affiliated and Other 351 576
Alabama Power | Related Party    
Receivables —    
Customer accounts and affiliated 142 126
Accounts payable —    
Affiliated and Other $ 200 $ 294
v3.26.1
Condensed Statements of Common Stockholders' Equity (Unaudited) - APC - USD ($)
shares in Millions, $ in Millions
Total
Common Stock
Paid-In Capital
Retained Earnings
Alabama Power
Alabama Power
Common Stock
Alabama Power
Paid-In Capital
Alabama Power
Retained Earnings
Alabama Power
Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2024   1,098       31      
Beginning balance at Dec. 31, 2024         $ 13,088 $ 1,222 $ 7,657 $ 4,214 $ (5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]                  
Net income $ 1,334       375     375  
Capital contributions from parent company         527   527    
Other comprehensive income         1       1
Cash dividends on common stock (791)     $ (791) (305)     (305)  
Other (5)   $ (1) (2) (1)       (1)
Ending balance (in shares) at Mar. 31, 2025   1,100       31      
Ending balance at Mar. 31, 2025         13,685 $ 1,222 8,184 4,284 (5)
Beginning balance (in shares) at Dec. 31, 2025   1,120       31      
Beginning balance at Dec. 31, 2025         13,994 $ 1,222 8,263 4,512 (3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]                  
Net income 1,356       425     425  
Capital contributions from parent company         226   226    
Other comprehensive income         0        
Cash dividends on common stock (830)     $ (830) (301)     (301)  
Other $ (3)   $ (1)            
Ending balance (in shares) at Mar. 31, 2026   1,128       31      
Ending balance at Mar. 31, 2026         $ 14,344 $ 1,222 $ 8,489 $ 4,636 $ (3)
v3.26.1
Condensed Statements of Income (Unaudited) - GPC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Revenues:    
Total operating revenues $ 8,397 $ 7,775
Operating Expenses:    
Other operations and maintenance 1,653 1,619
Depreciation and amortization 1,420 1,286
Taxes other than income taxes 464 445
Total operating expenses 6,379 5,765
Operating Income 2,018 2,010
Other Income and (Expense):    
Allowance for equity funds used during construction 121 73
Interest expense, net of amounts capitalized (778) (714)
Other income (expense), net 155 149
Total other income and (expense) (452) (460)
Earnings Before Income Taxes 1,566 1,550
Income taxes (benefit) 228 280
Consolidated Net Income Attributable to Southern Company 1,356 1,334
Retail revenues    
Operating Revenues:    
Total operating revenues 4,640 4,601
Wholesale revenues    
Operating Revenues:    
Total operating revenues 965 744
Other revenues    
Operating Revenues:    
Total operating revenues 336 349
Operating Expenses:    
Total cost of sales 181 199
Fuel    
Operating Expenses:    
Total cost of sales 1,491 1,292
Purchased power, non-affiliates    
Operating Expenses:    
Total cost of sales 244 250
GEORGIA POWER CO    
Operating Revenues:    
Total operating revenues 3,142 3,037
Operating Expenses:    
Other operations and maintenance 672 634
Depreciation and amortization 484 503
Taxes other than income taxes 176 170
Total operating expenses 2,380 2,256
Operating Income 762 781
Other Income and (Expense):    
Allowance for equity funds used during construction 97 48
Interest expense, net of amounts capitalized (204) (187)
Other income (expense), net 58 52
Total other income and (expense) (49) (87)
Earnings Before Income Taxes 713 694
Income taxes (benefit) 85 98
Consolidated Net Income Attributable to Southern Company 628 596
GEORGIA POWER CO | Retail revenues    
Operating Revenues:    
Total operating revenues 2,638 2,630
GEORGIA POWER CO | Wholesale revenues    
Operating Revenues:    
Total operating revenues 227 144
GEORGIA POWER CO | Other revenues    
Operating Revenues:    
Total operating revenues 277 263
GEORGIA POWER CO | Fuel    
Operating Expenses:    
Total cost of sales 601 524
GEORGIA POWER CO | Purchased power, non-affiliates    
Operating Expenses:    
Total cost of sales 158 161
GEORGIA POWER CO | Purchased power, affiliates    
Operating Expenses:    
Total cost of sales $ 289 $ 264
v3.26.1
Condensed Statements of Comprehensive Income (Unaudited) - GPC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Net income $ 1,356 $ 1,334
Qualifying hedges:    
Changes in fair value, net of tax (3) 14
Consolidated Comprehensive Income Attributable to Company 1,358 1,337
GEORGIA POWER CO    
Net income 628 596
Qualifying hedges:    
Changes in fair value, net of tax 0 (1)
Total other comprehensive income (loss) 0 (1)
Consolidated Comprehensive Income Attributable to Company $ 628 $ 595
v3.26.1
Condensed Statements of Comprehensive Income (Unaudited) - GPC (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Changes in fair value, tax $ (1) $ 5
GEORGIA POWER CO    
Changes in fair value, tax $ 0 $ (1)
v3.26.1
Condensed Statements of Cash Flows (Unaudited) - GPC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Activities:    
Net income $ 1,356 $ 1,334
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 1,580 1,411
Deferred income taxes 168 351
Allowance for equity funds used during construction (121) (73)
Pension, postretirement, and other employee benefits (149) (149)
Settlement of asset retirement obligations (133) (134)
Storm damage cost recovery – long-term (93) (173)
Other, net (25) (1)
Changes in certain current assets and liabilities —    
Receivables 124 7
Retail fuel cost under recovery 63 71
Other current assets (27) 66
Accounts payable (555) (394)
Accrued taxes (408) (418)
Accrued compensation (599) (537)
Other current liabilities (4) (37)
Net cash provided from operating activities 1,226 1,250
Investing Activities:    
Property additions (2,944) (2,437)
Nuclear decommissioning trust fund purchases (442) (361)
Nuclear decommissioning trust fund sales 442 361
Cost of removal, net of salvage (166) (168)
Other investing activities (60) (68)
Net cash used for investing activities (3,421) (2,834)
Financing Activities:    
Decrease in notes payable, net   (841)
Proceeds —    
Short-term borrowings 350 0
Redemptions and repurchases —    
Short-term borrowings (50) 0
Payment of common stock dividends (776) (736)
Other financing activities (191) (133)
Net cash provided from financing activities 1,542 2,815
Net Change in Cash, Cash Equivalents, and Restricted Cash (653) 1,231
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 1,640 1,101
Cash, Cash Equivalents, and Restricted Cash at End of Period 987 2,332
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 901 756
Noncash transactions —    
Accrued property additions at end of period 1,049 940
Right-of-use assets obtained under operating leases 41 87
Right-of-use assets obtained under finance leases 2 13
GEORGIA POWER CO    
Operating Activities:    
Net income 628 596
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 556 577
Deferred income taxes 95 91
Allowance for equity funds used during construction (97) (48)
Pension, postretirement, and other employee benefits (78) (74)
Settlement of asset retirement obligations (67) (66)
Storm damage cost recovery – long-term (93) (173)
Other, net (27) (38)
Changes in certain current assets and liabilities —    
Receivables 140 94
Retail fuel cost under recovery 78 83
Prepaid income taxes (55) 0
Other current assets (90) (23)
Accounts payable (131) (325)
Accrued taxes (352) (355)
Accrued compensation (75) (68)
Other current liabilities (52) 34
Net cash provided from operating activities 380 305
Investing Activities:    
Property additions (1,906) (1,429)
Nuclear decommissioning trust fund purchases (316) (246)
Nuclear decommissioning trust fund sales 316 246
Cost of removal, net of salvage (100) (103)
Change in construction payables, net of joint owner portion (271) (160)
Other investing activities (12) (27)
Net cash used for investing activities (2,289) (1,719)
Financing Activities:    
Decrease in notes payable, net (135) 0
Proceeds —    
Proceeds — Senior notes 0 1,600
Short-term borrowings 250 0
FFB loan 1,016 0
Redemptions and repurchases —    
Short-term borrowings (50) 0
FFB loan (21) (21)
Capital contributions from parent company 1,500 700
Payment of common stock dividends (644) (552)
Other financing activities (42) (48)
Net cash provided from financing activities 1,874 1,679
Net Change in Cash, Cash Equivalents, and Restricted Cash (35) 265
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 59 118
Cash, Cash Equivalents, and Restricted Cash at End of Period 24 383
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 218 188
Noncash transactions —    
Accrued property additions at end of period 753 551
Right-of-use assets obtained under operating leases 6 2
Right-of-use assets obtained under finance leases $ 2 $ 13
v3.26.1
Condensed Statements of Cash Flows (Unaudited) - GPC (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Net cash paid for capitalized interest $ 51 $ 29
GEORGIA POWER CO    
Net cash paid for capitalized interest $ 31 $ 16
v3.26.1
Condensed Balance Sheets (Unaudited) - GPC - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Current Assets:    
Cash and cash equivalents $ 981 $ 1,639
Receivables —    
Customer accounts, net and Affiliated 2,405 2,251
Unbilled revenues 740 931
Other accounts and notes 524 655
Fossil fuel stock 727 735
Materials and supplies 2,297 2,202
Regulatory assets – asset retirement obligations 353 353
Other regulatory assets 706 709
Other current assets 433 424
Total current assets 9,961 10,917
Property, Plant, and Equipment:    
In service 149,086 146,114
Less: Accumulated depreciation 45,186 43,483
Plant in service, net of depreciation 103,900 102,631
Nuclear fuel, at amortized cost 920 897
Construction work in progress 11,282 10,534
Total property, plant, and equipment 116,102 114,369
Other Property and Investments:    
Nuclear decommissioning trusts, at fair value 2,888 2,947
Equity investments in unconsolidated subsidiaries 1,365 1,318
Miscellaneous property and investments 706 714
Total other property and investments 10,414 10,440
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 1,351 1,358
Deferred charges related to income taxes 1,026 948
Prepaid pension costs 3,369 3,257
Deferred under recovered fuel clause revenues 210 252
Regulatory assets – asset retirement obligations, deferred 5,198 5,129
Other regulatory assets, deferred 7,683 7,427
Other deferred charges and assets 1,534 1,436
Total deferred charges and other assets 20,554 19,994
Total Assets 157,031 155,720
Current Liabilities:    
Securities due within one year 5,701 6,220
Notes payable 1,673 722
Accounts payable —    
Customer deposits 478 475
Accrued interest 627 807
Accrued compensation 761 1,418
Operating lease obligations 203 197
Asset retirement obligations 659 662
Other regulatory liabilities 228 240
Other current liabilities 1,191 1,157
Total current liabilities 15,318 16,888
Long-term Debt 67,148 65,649
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 12,381 12,133
Deferred credits related to income taxes 4,648 4,712
Accumulated deferred ITCs 2,047 2,002
Employee benefit obligations 941 980
Operating lease obligations, deferred 1,280 1,287
Asset retirement obligations, deferred 8,907 8,939
Other deferred credits and liabilities 1,625 1,505
Total deferred credits and other liabilities 34,653 34,316
Total Liabilities 117,119 116,853
Total Liabilities and Stockholders' Equity 157,031 155,720
GEORGIA POWER CO    
Current Assets:    
Cash and cash equivalents 24 59
Receivables —    
Unbilled revenues 302 346
Under recovered retail fuel clause revenues 234 310
Joint owner accounts 98 195
Other accounts and notes 69 61
Fossil fuel stock 368 362
Materials and supplies 1,042 994
Regulatory assets – asset retirement obligations 222 222
Other regulatory assets 336 335
Other current assets 371 285
Total current assets 4,077 4,258
Property, Plant, and Equipment:    
In service 60,443 59,458
Less: Accumulated depreciation 16,236 15,957
Plant in service, net of depreciation 44,207 43,501
Nuclear fuel, at amortized cost 635 606
Construction work in progress 7,623 6,764
Total property, plant, and equipment 52,465 50,871
Other Property and Investments:    
Nuclear decommissioning trusts, at fair value 1,378 1,405
Equity investments in unconsolidated subsidiaries 37 40
Miscellaneous property and investments 231 231
Total other property and investments 1,646 1,676
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 1,083 1,120
Deferred charges related to income taxes 738 660
Prepaid pension costs 1,142 1,099
Deferred under recovered fuel clause revenues 210 212
Regulatory assets – asset retirement obligations, deferred 3,397 3,382
Other regulatory assets, deferred 4,166 4,032
Other deferred charges and assets 796 767
Total deferred charges and other assets 11,532 11,272
Total Assets 69,720 68,077
Current Liabilities:    
Securities due within one year 2,266 1,370
Notes payable 225 160
Accounts payable —    
Customer deposits 273 267
Accrued taxes 326 678
Accrued interest 207 234
Accrued compensation 177 327
Operating lease obligations 174 170
Asset retirement obligations 355 360
Other regulatory liabilities 35 52
Other current liabilities 268 332
Total current liabilities 6,596 6,670
Long-term Debt 20,169 20,122
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 4,920 4,811
Deferred credits related to income taxes 2,198 2,225
Accumulated deferred ITCs 417 354
Employee benefit obligations 177 189
Operating lease obligations, deferred 924 960
Asset retirement obligations, deferred 5,158 5,167
Other deferred credits and liabilities 642 545
Total deferred credits and other liabilities 14,436 14,251
Total Liabilities 41,201 41,043
Total common stockholders' equity 28,519 27,034
Total Liabilities and Stockholders' Equity 69,720 68,077
GEORGIA POWER CO | Nonrelated Party    
Receivables —    
Customer accounts, net and Affiliated 929 993
Accounts payable —    
Affiliated and Other 1,512 1,728
GEORGIA POWER CO | Related Party    
Receivables —    
Customer accounts, net and Affiliated 82 96
Accounts payable —    
Affiliated and Other $ 778 $ 992
v3.26.1
Condensed Statements of Common Stockholders' Equity (Unaudited) - GPC - USD ($)
shares in Millions, $ in Millions
Total
Common Stock
Paid-In Capital
Retained Earnings
GEORGIA POWER CO
GEORGIA POWER CO
Common Stock
GEORGIA POWER CO
Paid-In Capital
GEORGIA POWER CO
Retained Earnings
GEORGIA POWER CO
Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2024   1,098       9      
Beginning balance at Dec. 31, 2024         $ 23,681 $ 398 $ 19,708 $ 3,562 $ 13
Increase (Decrease) in Stockholders' Equity [Roll Forward]                  
Net income $ 1,334       596     596  
Capital contributions from parent company         702   702    
Other comprehensive income         (1)       (1)
Cash dividends on common stock (791)     $ (791) (552)     (552)  
Other (5)   $ (1) (2)          
Ending balance (in shares) at Mar. 31, 2025   1,100       9      
Ending balance at Mar. 31, 2025         24,426 $ 398 20,410 3,606 12
Beginning balance (in shares) at Dec. 31, 2025   1,120       9      
Beginning balance at Dec. 31, 2025         27,034 $ 398 22,416 4,204 16
Increase (Decrease) in Stockholders' Equity [Roll Forward]                  
Net income 1,356       628     628  
Capital contributions from parent company         1,500   1,500    
Other comprehensive income         0        
Cash dividends on common stock (830)     $ (830) (644)     (644)  
Other $ (3)   $ (1)   1     1  
Ending balance (in shares) at Mar. 31, 2026   1,128       9      
Ending balance at Mar. 31, 2026         $ 28,519 $ 398 $ 23,916 $ 4,189 $ 16
v3.26.1
Condensed Statements of Income (Unaudited) - MPC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Revenues:    
Total operating revenues $ 8,397 $ 7,775
Operating Expenses:    
Other operations and maintenance 1,653 1,619
Depreciation and amortization 1,420 1,286
Taxes other than income taxes 464 445
Total operating expenses 6,379 5,765
Operating Income 2,018 2,010
Other Income and (Expense):    
Interest expense, net of amounts capitalized (778) (714)
Other income (expense), net 155 149
Total other income and (expense) (452) (460)
Earnings Before Income Taxes 1,566 1,550
Income taxes (benefit) 228 280
Consolidated Net Income Attributable to Southern Company 1,356 1,334
Retail revenues    
Operating Revenues:    
Total operating revenues 4,640 4,601
Other revenues    
Operating Revenues:    
Total operating revenues 336 349
Operating Expenses:    
Fuel and purchased power 181 199
Mississippi Power    
Operating Revenues:    
Total operating revenues 472 420
Operating Expenses:    
Other operations and maintenance 88 84
Depreciation and amortization 55 52
Taxes other than income taxes 36 33
Total operating expenses 384 335
Operating Income 88 85
Other Income and (Expense):    
Interest expense, net of amounts capitalized (20) (20)
Other income (expense), net 10 6
Total other income and (expense) (10) (14)
Earnings Before Income Taxes 78 71
Income taxes (benefit) 18 16
Consolidated Net Income Attributable to Southern Company 60 55
Mississippi Power | Retail revenues    
Operating Revenues:    
Total operating revenues 273 248
Mississippi Power | Wholesale revenues, non-affiliates    
Operating Revenues:    
Total operating revenues 87 71
Mississippi Power | Wholesale revenues, affiliates    
Operating Revenues:    
Total operating revenues 97 81
Mississippi Power | Other revenues    
Operating Revenues:    
Total operating revenues 15 20
Mississippi Power | Fuel and purchased power    
Operating Expenses:    
Fuel and purchased power $ 205 $ 166
v3.26.1
Condensed Statements of Cash Flows (Unaudited) - MPC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Activities:    
Net income $ 1,356 $ 1,334
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 1,580 1,411
Deferred income taxes 168 351
Pension, postretirement, and other employee benefits (149) (149)
Settlement of asset retirement obligations (133) (134)
Other, net (25) (1)
Changes in certain current assets and liabilities —    
Receivables 124 7
Retail fuel cost under recovery 63 71
Other current assets (27) 66
Accounts payable (555) (394)
Accrued taxes (408) (418)
Accrued interest (180) (82)
Accrued compensation (599) (537)
Other current liabilities (4) (37)
Net cash provided from operating activities 1,226 1,250
Investing Activities:    
Property additions (2,944) (2,437)
Cost of removal, net of salvage (166) (168)
Change in construction payables, net (251) (161)
Other investing activities (60) (68)
Net cash used for investing activities (3,421) (2,834)
Financing Activities:    
Increase (decrease) in notes payable, net 653  
Decrease in notes payable, net   (841)
Payment of common stock dividends (776) (736)
Other financing activities (191) (133)
Net cash provided from financing activities 1,542 2,815
Net Change in Cash, Cash Equivalents, and Restricted Cash (653) 1,231
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 1,640 1,101
Cash, Cash Equivalents, and Restricted Cash at End of Period 987 2,332
Supplemental Cash Flow Information:    
Interest 901 756
Noncash transactions —    
Accrued property additions at end of period 1,049 940
Right-of-use assets obtained under operating leases 41 87
Mississippi Power    
Operating Activities:    
Net income 60 55
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 61 56
Deferred income taxes 10 (7)
Pension, postretirement, and other employee benefits (5) (5)
Settlement of asset retirement obligations (4) (4)
Other, net (5) 7
Changes in certain current assets and liabilities —    
Receivables (9) (16)
Retail fuel cost under recovery (15) (13)
Fossil fuel stock (1) 13
Other current assets (2) 10
Accounts payable (28) (4)
Accrued taxes (73) (64)
Accrued interest (12) (11)
Accrued compensation (26) (23)
Other current liabilities 0 (5)
Net cash provided from operating activities (49) (11)
Investing Activities:    
Property additions (92) (72)
Contributions in aid of construction 2 57
Cost of removal, net of salvage (9) (8)
Change in construction payables, net (1) (14)
Payments pursuant to LTSAs (6) (6)
Other investing activities 0 (1)
Net cash used for investing activities (106) (44)
Financing Activities:    
Increase (decrease) in notes payable, net 32  
Decrease in notes payable, net   (14)
Proceeds — Senior notes 75 100
Capital contributions from parent company 90 50
Payment of common stock dividends (48) (48)
Other financing activities (1) (1)
Net cash provided from financing activities 148 87
Net Change in Cash, Cash Equivalents, and Restricted Cash (7) 32
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 26 13
Cash, Cash Equivalents, and Restricted Cash at End of Period 19 45
Supplemental Cash Flow Information:    
Interest 32 30
Noncash transactions —    
Accrued property additions at end of period 37 22
Right-of-use assets obtained under operating leases $ 3 $ 0
v3.26.1
Condensed Balance Sheets (Unaudited) - MPC - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Current Assets:    
Cash and cash equivalents $ 981 $ 1,639
Receivables —    
Customer accounts, net and Affiliated 2,405 2,251
Unbilled revenues 740 931
Other accounts and notes 524 655
Fossil fuel stock 727 735
Materials and supplies 2,297 2,202
Other regulatory assets 706 709
Other current assets 433 424
Total current assets 9,961 10,917
Property, Plant, and Equipment:    
In service 149,086 146,114
Less: Accumulated depreciation 45,186 43,483
Plant in service, net of depreciation 103,900 102,631
Construction work in progress 11,282 10,534
Total property, plant, and equipment 116,102 114,369
Other Property and Investments:    
Total other property and investments 10,414 10,440
Deferred Charges and Other Assets:    
Deferred charges related to income taxes 1,026 948
Prepaid pension costs 3,369 3,257
Deferred under recovered fuel clause revenues 210 252
Regulatory assets – asset retirement obligations 5,198 5,129
Other regulatory assets, deferred 7,683 7,427
Other deferred charges and assets 1,534 1,436
Total deferred charges and other assets 20,554 19,994
Total Assets 157,031 155,720
Current Liabilities:    
Securities due within one year 5,701 6,220
Notes payable 1,673 722
Accounts payable —    
Accrued compensation 761 1,418
Asset retirement obligations 659 662
Other regulatory liabilities 228 240
Other current liabilities 1,191 1,157
Total current liabilities 15,318 16,888
Long-term Debt 67,148 65,649
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 12,381 12,133
Deferred credits related to income taxes 4,648 4,712
Employee benefit obligations 941 980
Asset retirement obligations, deferred 8,907 8,939
Other cost of removal obligations 2,054 2,036
Other regulatory liabilities, deferred 770 722
Other deferred credits and liabilities 1,625 1,505
Total deferred credits and other liabilities 34,653 34,316
Total Liabilities 117,119 116,853
Total Liabilities and Stockholders' Equity 157,031 155,720
Mississippi Power    
Current Assets:    
Cash and cash equivalents 19 26
Receivables —    
Unbilled revenues 39 44
Other accounts and notes 24 22
Fossil fuel stock 48 46
Materials and supplies 103 101
Other regulatory assets 52 49
Other current assets 7 10
Total current assets 436 374
Property, Plant, and Equipment:    
In service 6,057 5,972
Less: Accumulated depreciation 1,990 1,922
Plant in service, net of depreciation 4,067 4,050
Construction work in progress 248 238
Total property, plant, and equipment 4,315 4,288
Other Property and Investments:    
Total other property and investments 142 143
Deferred Charges and Other Assets:    
Deferred charges related to income taxes 25 25
Prepaid pension costs 157 151
Deferred under recovered fuel clause revenues 0 40
Regulatory assets – asset retirement obligations 228 229
Other regulatory assets, deferred 259 255
Accumulated deferred income taxes 62 66
Other deferred charges and assets 79 66
Total deferred charges and other assets 810 832
Total Assets 5,703 5,637
Current Liabilities:    
Securities due within one year 65 66
Notes payable 32 0
Accounts payable —    
Accrued taxes 52 125
Accrued compensation 25 49
Asset retirement obligations 19 21
Other regulatory liabilities 12 20
Other current liabilities 87 92
Total current liabilities 416 520
Long-term Debt 1,795 1,720
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 499 491
Deferred credits related to income taxes 209 211
Employee benefit obligations 65 67
Asset retirement obligations, deferred 100 103
Other cost of removal obligations 110 115
Other regulatory liabilities, deferred 140 141
Other deferred credits and liabilities 78 80
Total deferred credits and other liabilities 1,201 1,208
Total Liabilities 3,412 3,448
Total common stockholders' equity 2,291 2,189
Total Liabilities and Stockholders' Equity 5,703 5,637
Mississippi Power | Nonrelated Party    
Receivables —    
Customer accounts, net and Affiliated 113 50
Accounts payable —    
Affiliated and Other 60 77
Mississippi Power | Related Party    
Receivables —    
Customer accounts, net and Affiliated 31 26
Accounts payable —    
Affiliated and Other $ 64 $ 70
v3.26.1
Condensed Statements of Common Stockholders' Equity (Unaudited) - MPC - USD ($)
shares in Millions, $ in Millions
Total
Common Stock
Paid-In Capital
Retained Earnings
Mississippi Power
Mississippi Power
Common Stock
Mississippi Power
Paid-In Capital
Mississippi Power
Retained Earnings
Mississippi Power
Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2024   1,098       1      
Beginning balance at Dec. 31, 2024         $ 2,089 $ 38 $ 4,791 $ (2,745) $ 5
Increase (Decrease) in Stockholders' Equity [Roll Forward]                  
Net income $ 1,334       55     55  
Capital contributions from parent company         51   51    
Cash dividends on common stock (791)     $ (791) (48)     (48)  
Other (5)   $ (1) (2) (1)       (1)
Ending balance (in shares) at Mar. 31, 2025   1,100       1      
Ending balance at Mar. 31, 2025         2,146 $ 38 4,842 (2,738) 4
Beginning balance (in shares) at Dec. 31, 2025   1,120       1      
Beginning balance at Dec. 31, 2025         2,189 $ 38 4,871 (2,724) 4
Increase (Decrease) in Stockholders' Equity [Roll Forward]                  
Net income 1,356       60     60  
Capital contributions from parent company         90   90    
Cash dividends on common stock (830)     $ (830) (48)     (48)  
Other $ (3)   $ (1)            
Ending balance (in shares) at Mar. 31, 2026   1,128       1      
Ending balance at Mar. 31, 2026         $ 2,291 $ 38 $ 4,961 $ (2,712) $ 4
v3.26.1
Condensed Consolidated Statements of Income (Unaudited) - SPC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Revenues:    
Total operating revenues $ 8,397 $ 7,775
Operating Expenses:    
Other operations and maintenance 1,653 1,619
Depreciation and amortization 1,420 1,286
Taxes other than income taxes 464 445
Total operating expenses 6,379 5,765
Operating Income 2,018 2,010
Other Income and (Expense):    
Interest expense, net of amounts capitalized (778) (714)
Other income (expense), net 155 149
Total other income and (expense) (452) (460)
Earnings Before Income Taxes 1,566 1,550
Income taxes (benefit) 228 280
Consolidated Net Income 1,338 1,270
Net loss attributable to noncontrolling interests (18) (64)
Consolidated Net Income Attributable to Southern Company 1,356 1,334
Other revenues    
Operating Revenues:    
Total operating revenues 336 349
Operating Expenses:    
Total cost of sales 181 199
Fuel    
Operating Expenses:    
Total cost of sales 1,491 1,292
Purchased power    
Operating Expenses:    
Total cost of sales 244 250
SOUTHERN POWER CO    
Operating Revenues:    
Total operating revenues 681 567
Operating Expenses:    
Other operations and maintenance 137 123
Depreciation and amortization 278 152
Taxes other than income taxes 13 12
Total operating expenses 740 522
Operating Income (59) 45
Other Income and (Expense):    
Interest expense, net of amounts capitalized (27) (26)
Other income (expense), net 2 3
Total other income and (expense) (25) (23)
Earnings Before Income Taxes (84) 22
Income taxes (benefit) (70) (1)
Consolidated Net Income (14) 23
Net loss attributable to noncontrolling interests (18) (64)
Consolidated Net Income Attributable to Southern Company 4 87
SOUTHERN POWER CO | Wholesale revenues, non-affiliates    
Operating Revenues:    
Total operating revenues 577 447
SOUTHERN POWER CO | Wholesale revenues, affiliates    
Operating Revenues:    
Total operating revenues 100 116
SOUTHERN POWER CO | Other revenues    
Operating Revenues:    
Total operating revenues 4 4
SOUTHERN POWER CO | Fuel    
Operating Expenses:    
Total cost of sales 254 207
SOUTHERN POWER CO | Purchased power    
Operating Expenses:    
Total cost of sales $ 58 $ 28
v3.26.1
Condensed Consolidated Statements of Comprehensive Income (Unaudited) - SPC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Net income $ 1,338 $ 1,270
Qualifying hedges:    
Changes in fair value, net of tax (3) 14
Reclassification adjustment for amounts included in net income, net of tax 4 (12)
Total other comprehensive income 2 3
Comprehensive Income 1,340 1,273
Comprehensive loss attributable to noncontrolling interests (18) (64)
Consolidated Comprehensive Income Attributable to Company 1,358 1,337
SOUTHERN POWER CO    
Net income (14) 23
Qualifying hedges:    
Changes in fair value, net of tax (8) 16
Reclassification adjustment for amounts included in net income, net of tax 10 (14)
Total other comprehensive income 2 2
Comprehensive Income (12) 25
Comprehensive loss attributable to noncontrolling interests (18) (64)
Consolidated Comprehensive Income Attributable to Company $ 6 $ 89
v3.26.1
Condensed Consolidated Statements of Comprehensive Income (Unaudited) - SPC (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Changes in fair value, tax $ (1) $ 5
Reclassification adjustment for amounts included in net income, tax 1 (4)
SOUTHERN POWER CO    
Changes in fair value, tax (2) 5
Reclassification adjustment for amounts included in net income, tax $ 3 $ (5)
v3.26.1
Condensed Consolidated Statements of Cash Flows (Unaudited) - SPC - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Activities:    
Net income $ 1,338 $ 1,270
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 1,580 1,411
Deferred income taxes 168 351
Other, net (25) (1)
Changes in certain current assets and liabilities —    
Receivables 124 7
Other current assets (27) 66
Accounts payable (555) (394)
Accrued compensation (599) (537)
Other current liabilities (4) (37)
Net cash provided from operating activities 1,226 1,250
Investing Activities:    
Property additions (2,944) (2,437)
Other investing activities (60) (68)
Net cash used for investing activities (3,421) (2,834)
Financing Activities:    
Increase (decrease) in notes payable, net 653  
Increase in notes payable, net   (841)
Distributions to noncontrolling interests (47) (37)
Payment of common stock dividends (776) (736)
Other financing activities (191) (133)
Net cash provided from financing activities 1,542 2,815
Net Change in Cash, Cash Equivalents, and Restricted Cash (653) 1,231
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 1,640 1,101
Cash, Cash Equivalents, and Restricted Cash at End of Period 987 2,332
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 901 756
Income taxes, net (excludes credit transfers) 0 (1)
Noncash transactions —    
Accrued property additions at end of period 1,049 940
Right-of-use assets obtained under operating leases 41 87
SOUTHERN POWER CO    
Operating Activities:    
Net income (14) 23
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 283 158
Deferred income taxes (27) 5
Amortization of ITCs (15) (15)
Loss on damaged equipment 20 0
Other, net 0 1
Changes in certain current assets and liabilities —    
Receivables 23 (5)
Income taxes receivable (43) (6)
Other current assets 14 5
Accounts payable (46) (27)
Accrued compensation (15) (15)
Other current liabilities 13 22
Net cash provided from operating activities 193 146
Investing Activities:    
Property additions (119) (187)
Change in construction payables 2 39
Payments pursuant to LTSAs (14) (13)
Other investing activities 2 0
Net cash used for investing activities (129) (161)
Financing Activities:    
Increase (decrease) in notes payable, net 23  
Increase in notes payable, net   0
Capital contributions from parent company 0 130
Capital contributions from noncontrolling interests 4 19
Distributions to noncontrolling interests (47) (37)
Payment of common stock dividends (72) (70)
Other financing activities (5) (3)
Net cash provided from financing activities (97) 39
Net Change in Cash, Cash Equivalents, and Restricted Cash (33) 24
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 105 168
Cash, Cash Equivalents, and Restricted Cash at End of Period 72 192
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 13 22
Income taxes, net (excludes credit transfers) 1 0
Noncash transactions —    
Accrued property additions at end of period 55 99
Right-of-use assets obtained under operating leases $ 0 $ 2
v3.26.1
Condensed Consolidated Statements of Cash Flows (Unaudited) - SPC (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Net cash paid for capitalized interest $ 51 $ 29
SOUTHERN POWER CO    
Net cash paid for capitalized interest $ 10 $ 3
v3.26.1
Condensed Consolidated Balance Sheets (Unaudited) - SPC - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Current Assets:    
Cash and cash equivalents $ 981 $ 1,639
Receivables —    
Customer accounts, net and Affiliated 2,405 2,251
Other 524 655
Materials and supplies 2,297 2,202
Other current assets 433 424
Total current assets 9,961 10,917
Property, Plant, and Equipment:    
In service 149,086 146,114
Less: Accumulated depreciation 45,186 43,483
Plant in service, net of depreciation 103,900 102,631
Construction work in progress 11,282 10,534
Total property, plant, and equipment 116,102 114,369
Other Property and Investments:    
Total other property and investments 10,414 10,440
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 1,351 1,358
Other deferred charges and assets 1,534 1,436
Total deferred charges and other assets 20,554 19,994
Total Assets 157,031 155,720
Current Liabilities:    
Securities due within one year 5,701 6,220
Notes payable 1,673 722
Accounts payable —    
Accrued interest 627 807
Operating lease obligations 203 197
Other current liabilities 1,191 1,157
Total current liabilities 15,318 16,888
Long-term Debt 67,148 65,649
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 12,381 12,133
Accumulated deferred ITCs 2,047 2,002
Operating lease obligations, deferred 1,280 1,287
Other deferred credits and liabilities 1,625 1,505
Total deferred credits and other liabilities 34,653 34,316
Total Liabilities 117,119 116,853
Total Stockholders' Equity (See accompanying statements) 39,912 38,867
Total Liabilities and Stockholders' Equity 157,031 155,720
SOUTHERN POWER CO    
Current Assets:    
Cash and cash equivalents 72 105
Receivables —    
Other 62 16
Materials and supplies 135 132
Other current assets 77 89
Total current assets 509 528
Property, Plant, and Equipment:    
In service 15,342 15,034
Less: Accumulated depreciation 5,488 5,214
Plant in service, net of depreciation 9,854 9,820
Construction work in progress 867 1,080
Total property, plant, and equipment 10,721 10,900
Other Property and Investments:    
Intangible assets, net of amortization 199 203
Net investment in sales-type leases 135 137
Total other property and investments 334 340
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 477 479
Prepaid LTSAs 183 170
Other deferred charges and assets 250 240
Total deferred charges and other assets 910 889
Total Assets 12,474 12,657
Current Liabilities:    
Securities due within one year 575 587
Notes payable 160 138
Accounts payable —    
Accrued taxes 13 9
Accrued interest 46 38
Operating lease obligations 31 31
Other current liabilities 77 92
Total current liabilities 1,038 1,076
Long-term Debt 2,353 2,353
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 571 579
Accumulated deferred ITCs 1,368 1,383
Operating lease obligations, deferred 508 510
Other deferred credits and liabilities 242 235
Total deferred credits and other liabilities 2,689 2,707
Total Liabilities 6,080 6,136
Total Stockholders' Equity (See accompanying statements) 6,394 6,521
Total Liabilities and Stockholders' Equity 12,474 12,657
SOUTHERN POWER CO | Nonrelated Party    
Receivables —    
Customer accounts, net and Affiliated 141 151
Accounts payable —    
Affiliated and Other 78 93
SOUTHERN POWER CO | Related Party    
Receivables —    
Customer accounts, net and Affiliated 22 35
Accounts payable —    
Affiliated and Other $ 58 $ 88
v3.26.1
Condensed Consolidated Balance Sheets (Unaudited) - SPC (Parenthetical) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Other intangible assets, amortization $ 450 $ 444
SOUTHERN POWER CO    
Other intangible assets, amortization $ 193 $ 188
v3.26.1
Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - SPC - USD ($)
$ in Millions
Total
Paid-In Capital
Retained Earnings
Accumulated Other Comprehensive Income (Loss)
Noncontrolling Interests
SOUTHERN POWER CO
SOUTHERN POWER CO
Total Common Stockholder's Equity
SOUTHERN POWER CO
Paid-In Capital
SOUTHERN POWER CO
Retained Earnings
SOUTHERN POWER CO
Accumulated Other Comprehensive Income (Loss)
SOUTHERN POWER CO
Noncontrolling Interests
Beginning balance at Dec. 31, 2024 $ 36,674 $ 14,149 $ 13,750 $ (78) $ 3,466 $ 6,682 $ 3,216 $ 1,306 $ 1,912 $ (2) $ 3,466
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Net income (loss) 1,270   1,334   (64) 23 87   87   (64)
Capital contributions from parent company           130 130 130      
Other comprehensive income 3     3   2 2     2  
Cash dividends on common stock (791)   (791)     (70) (70)   (70)    
Capital contributions from noncontrolling interests 19       19 19         19
Distributions to noncontrolling interests (37)       (37) (37)         (37)
Other (5) (1) (2)                
Ending balance at Mar. 31, 2025 37,223 14,231 14,291 (75) 3,384 6,749 3,365 1,436 1,929 0 3,384
Beginning balance at Dec. 31, 2025 38,867 15,740 14,856 (75) 2,851 6,521 3,670 1,912 1,758 0 2,851
Increase (Decrease) in Stockholders' Equity [Roll Forward]                      
Net income (loss) 1,338   1,356   (18) (14) 4   4   (18)
Other comprehensive income 2     2   2 2     2  
Cash dividends on common stock (830)   (830)     (72) (72)   (72)    
Capital contributions from noncontrolling interests 4       4 4         4
Distributions to noncontrolling interests (46)       (46) (46)         (46)
Other (3) (1)     (1) (1)   (1) 1   (1)
Ending balance at Mar. 31, 2026 $ 39,912 $ 16,285 $ 15,382 $ (73) $ 2,790 $ 6,394 $ 3,604 $ 1,911 $ 1,691 $ 2 $ 2,790
v3.26.1
Condensed Consolidated Statements of Income (Unaudited) - GAS - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Revenues:    
Total operating revenues $ 8,397 $ 7,775
Operating Expenses:    
Other operations and maintenance 1,653 1,619
Depreciation and amortization 1,420 1,286
Taxes other than income taxes 464 445
Total operating expenses 6,379 5,765
Operating Income 2,018 2,010
Other Income and (Expense):    
Earnings from equity method investments 50 32
Interest expense, net of amounts capitalized (778) (714)
Other income (expense), net 155 149
Total other income and (expense) (452) (460)
Earnings Before Income Taxes 1,566 1,550
Income taxes (benefit) 228 280
Consolidated Net Income Attributable to Southern Company 1,356 1,334
SOUTHERN Co GAS    
Operating Revenues:    
Total operating revenues $ 2,191 $ 1,839
Revenue, Product and Service [Extensible Enumeration] Natural gas Natural gas
Operating Expenses:    
Total cost of sales $ 926 $ 674
Cost, Product and Service [Extensible Enumeration] Natural gas Natural gas
Other operations and maintenance $ 343 $ 316
Depreciation and amortization 183 169
Taxes other than income taxes 105 97
Total operating expenses 1,557 1,256
Operating Income 634 583
Other Income and (Expense):    
Earnings from equity method investments 46 39
Interest expense, net of amounts capitalized (105) (92)
Other income (expense), net 17 18
Total other income and (expense) (42) (35)
Earnings Before Income Taxes 592 548
Income taxes (benefit) 145 130
Consolidated Net Income Attributable to Southern Company $ 447 $ 418
v3.26.1
Condensed Consolidated Statements of Income (Unaudited) - GAS (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
SOUTHERN Co GAS    
Revenue taxes collected $ 70 $ 63
v3.26.1
Condensed Consolidated Statements of Comprehensive Income (Unaudited) - GAS - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Net income $ 1,356 $ 1,334
Qualifying hedges:    
Changes in fair value, net of tax (3) 14
Reclassification adjustment for amounts included in net income, net of tax 4 (12)
Pension and other postretirement benefit plans:    
Consolidated Comprehensive Income Attributable to Company 1,358 1,337
SOUTHERN Co GAS    
Net income 447 418
Qualifying hedges:    
Changes in fair value, net of tax 6 11
Reclassification adjustment for amounts included in net income, net of tax (7) 1
Pension and other postretirement benefit plans:    
Reclassification adjustment for amounts included in net income, net of tax (1) 0
Total other comprehensive income (loss) (2) 12
Consolidated Comprehensive Income Attributable to Company $ 445 $ 430
v3.26.1
Condensed Consolidated Statements of Comprehensive Income (Unaudited) - GAS (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Changes in fair value, tax $ (1) $ 5
Qualifying hedges, reclassification adjustment, tax 1 (4)
SOUTHERN Co GAS    
Changes in fair value, tax 2 5
Qualifying hedges, reclassification adjustment, tax (3) 0
Reclassification adjustment for amounts included in net income, tax $ 0 $ 0
v3.26.1
Condensed Consolidated Statements of Cash Flows (Unaudited) - GAS - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Operating Activities:    
Net income $ 1,356 $ 1,334
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 1,580 1,411
Deferred income taxes 168 351
Other, net (25) (1)
Changes in certain current assets and liabilities —    
Receivables 124 7
Natural gas for sale, net of temporary LIFO liquidation 355 365
Other current assets (27) 66
Accounts payable (555) (394)
Accrued compensation (599) (537)
Other current liabilities (4) (37)
Net cash provided from operating activities 1,226 1,250
Investing Activities:    
Property additions (2,944) (2,437)
Cost of removal, net of salvage (166) (168)
Change in construction payables, net (251) (161)
Other investing activities (60) (68)
Net cash used for investing activities (3,421) (2,834)
Financing Activities:    
Decrease in notes payable, net   (841)
Payment of common stock dividends (776) (736)
Other financing activities (191) (133)
Net cash provided from financing activities 1,542 2,815
Net Change in Cash, Cash Equivalents, and Restricted Cash (653) 1,231
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 1,640 1,101
Cash, Cash Equivalents, and Restricted Cash at End of Period 987 2,332
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 901 756
Income taxes, net (excludes credit transfers) 0 (1)
Noncash transactions —    
Accrued property additions at end of period 1,049 940
Right-of-use assets obtained under operating leases 41 87
SOUTHERN Co GAS    
Operating Activities:    
Net income 447 418
Adjustments to reconcile net income to net cash provided from operating activities —    
Depreciation and amortization, total 183 167
Deferred income taxes 60 42
Other, net 21 (5)
Changes in certain current assets and liabilities —    
Receivables (51) (115)
Natural gas for sale, net of temporary LIFO liquidation 355 365
Other current assets 30 74
Accounts payable (201) (95)
Accrued taxes 70 73
Accrued compensation (56) (60)
Natural gas cost over recovery (27) (179)
Other current liabilities (23) 2
Net cash provided from operating activities 808 687
Investing Activities:    
Property additions (323) (281)
Cost of removal, net of salvage (16) (16)
Change in construction payables, net 6 (6)
Capital contributions to unconsolidated subsidiaries (27) (19)
Other investing activities 0 1
Net cash used for investing activities (360) (321)
Financing Activities:    
Decrease in notes payable, net (170) (141)
Return of capital to parent company 0 (23)
Payment of common stock dividends (141) (149)
Other financing activities (10) (10)
Net cash provided from financing activities (321) (323)
Net Change in Cash, Cash Equivalents, and Restricted Cash 127 43
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period 15 44
Cash, Cash Equivalents, and Restricted Cash at End of Period 142 87
Supplemental Cash Flow Information:    
Interest, net of amounts capitalized 129 111
Income taxes, net (excludes credit transfers) (1) (1)
Noncash transactions —    
Accrued property additions at end of period 118 104
Right-of-use assets obtained under operating leases 1 60
Return of capital to parent company $ 0 $ 33
v3.26.1
Condensed Consolidated Statements of Cash Flows (Unaudited) - GAS (Parenthetical) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Net cash paid for capitalized interest $ 51 $ 29
SOUTHERN Co GAS    
Net cash paid for capitalized interest $ 4 $ 5
v3.26.1
Condensed Consolidated Balance Sheets (Unaudited) - GAS - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Current Assets:    
Cash and cash equivalents $ 981 $ 1,639
Receivables —    
Customer accounts 2,405 2,251
Unbilled revenues 740 931
Other accounts and notes 524 655
Accumulated provision for uncollectible accounts (95) (84)
Materials and supplies 2,297 2,202
Natural gas for sale 145 396
Prepaid expenses 411 327
Other regulatory assets 706 709
Other current assets 433 424
Total current assets 9,961 10,917
Property, Plant, and Equipment:    
In service 149,086 146,114
Less: Accumulated depreciation 45,186 43,483
Plant in service, net of depreciation 103,900 102,631
Construction work in progress 11,282 10,534
Total property, plant, and equipment 116,102 114,369
Other Property and Investments:    
Goodwill 5,161 5,161
Equity investments in unconsolidated subsidiaries 1,365 1,318
Other intangible assets, net of amortization 294 300
Miscellaneous property and investments 706 714
Total other property and investments 10,414 10,440
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 1,351 1,358
Other regulatory assets, deferred 7,683 7,427
Other deferred charges and assets 1,534 1,436
Total deferred charges and other assets 20,554 19,994
Total Assets 157,031 155,720
Current Liabilities:    
Securities due within one year 5,701 6,220
Notes payable 1,673 722
Accounts payable —    
Customer deposits 478 475
Accrued interest 627 807
Accrued compensation 761 1,418
Natural gas cost over recovery 131 158
Other regulatory liabilities 228 240
Other current liabilities 1,191 1,157
Total current liabilities 15,318 16,888
Long-term Debt 67,148 65,649
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 12,381 12,133
Deferred credits related to income taxes 4,648 4,712
Employee benefit obligations 941 980
Operating lease obligations 1,280 1,287
Other cost of removal obligations 2,054 2,036
Other deferred credits and liabilities 1,625 1,505
Total deferred credits and other liabilities 34,653 34,316
Total Liabilities 117,119 116,853
Total Liabilities and Stockholders' Equity 157,031 155,720
SOUTHERN Co GAS    
Current Assets:    
Cash and cash equivalents 137 15
Receivables —    
Customer accounts 660 490
Unbilled revenues 229 341
Other accounts and notes 60 57
Accumulated provision for uncollectible accounts (59) (50)
Materials and supplies 62 62
Natural gas for sale 145 396
Prepaid expenses 27 26
Other regulatory assets 96 114
Other current assets 44 66
Total current assets 1,401 1,517
Property, Plant, and Equipment:    
In service 24,391 24,098
Less: Accumulated depreciation 6,386 6,273
Plant in service, net of depreciation 18,005 17,825
Construction work in progress 865 863
Total property, plant, and equipment 18,870 18,688
Other Property and Investments:    
Goodwill 5,015 5,015
Equity investments in unconsolidated subsidiaries 1,224 1,182
Other intangible assets, net of amortization 2 3
Miscellaneous property and investments 25 24
Total other property and investments 6,266 6,224
Deferred Charges and Other Assets:    
Operating lease right-of-use assets, net of amortization 82 85
Prepaid pension and other postretirement benefit costs 248 229
Other regulatory assets, deferred 555 517
Other deferred charges and assets 129 127
Total deferred charges and other assets 1,014 958
Total Assets 27,551 27,387
Current Liabilities:    
Securities due within one year 531 531
Notes payable 255 425
Accounts payable —    
Customer deposits 72 75
Accrued taxes 177 107
Accrued interest 77 100
Accrued compensation 81 137
Temporary LIFO liquidation 104 0
Natural gas cost over recovery 131 158
Other regulatory liabilities 69 36
Other current liabilities 109 110
Total current liabilities 2,046 2,302
Long-term Debt 8,738 8,743
Deferred Credits and Other Liabilities:    
Accumulated deferred income taxes 2,033 1,971
Deferred credits related to income taxes 672 681
Employee benefit obligations 84 78
Operating lease obligations 122 123
Other cost of removal obligations 1,944 1,921
Accrued environmental remediation 201 207
Other deferred credits and liabilities 278 234
Total deferred credits and other liabilities 5,334 5,215
Total Liabilities 16,118 16,260
Total common stockholders' equity 11,433 11,127
Total Liabilities and Stockholders' Equity 27,551 27,387
SOUTHERN Co GAS | Related Party    
Accounts payable —    
Affiliated and Other 57 70
SOUTHERN Co GAS | Nonrelated Party    
Accounts payable —    
Affiliated and Other $ 383 $ 553
v3.26.1
Condensed Consolidated Balance Sheets (Unaudited) - GAS (Parenthetical) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Other intangible assets, amortization $ 450 $ 444
SOUTHERN Co GAS    
Other intangible assets, amortization $ 180 $ 179
v3.26.1
Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - GAS - USD ($)
$ in Millions
Total
Paid-In Capital
Retained Earnings
SOUTHERN Co GAS
SOUTHERN Co GAS
Paid-In Capital
SOUTHERN Co GAS
Retained Earnings
SOUTHERN Co GAS
Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2024       $ 10,996 $ 10,863 $ 85 $ 48
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income $ 1,334     418   418  
Return of capital to parent company       (56) (56)    
Capital contributions from parent company       3 3    
Other comprehensive income       12     12
Cash dividends on common stock (791)   $ (791) (149)   (149)  
Other (5) $ (1) (2) 1   1  
Ending balance at Mar. 31, 2025       11,225 10,810 355 60
Beginning balance at Dec. 31, 2025       11,127 10,854 222 51
Increase (Decrease) in Stockholders' Equity [Roll Forward]              
Net income 1,356     447   447  
Capital contributions from parent company       1 1    
Other comprehensive income       (2)     (2)
Cash dividends on common stock (830)   $ (830) (141)   (141)  
Other $ (3) $ (1)   1   1  
Ending balance at Mar. 31, 2026       $ 11,433 $ 10,855 $ 529 $ 49
v3.26.1
Introduction
 3 Months Ended
Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Introduction INTRODUCTION
The condensed quarterly financial statements of each Registrant included herein have been prepared by such Registrant, without audit, pursuant to the rules and regulations of the SEC. The Condensed Balance Sheets at December 31, 2025 have been derived from the audited financial statements of each Registrant. In the opinion of each Registrant's management, the information regarding such Registrant furnished herein reflects all adjustments, which, except as otherwise disclosed, are of a normal recurring nature, necessary to present fairly the results of operations for the periods ended March 31, 2026 and 2025. Certain information and disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although each Registrant believes that the disclosures regarding such Registrant are adequate to make the information presented not misleading. Disclosures which would substantially duplicate the disclosures in the Form 10-K and details which have not changed significantly in amount or composition since the filing of the Form 10-K are generally omitted from this Quarterly Report on Form 10-Q unless specifically required by GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K. Due to the seasonal variations in the demand for energy and other factors, operating results for the periods presented are not necessarily indicative of the operating results to be expected for the full year.
The preparation of financial statements in conformity with GAAP requires the use of estimates, and the actual results may differ from those estimates. Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. These reclassifications had no impact on the overall results of operations, financial position, or cash flows of any Registrant.
Goodwill and Other Intangible Assets
Goodwill at both March 31, 2026 and December 31, 2025 was as follows:
Goodwill
(in millions)
Southern Company$5,161 
Southern Company Gas:
Gas distribution operations$4,034 
Gas marketing services981 
Southern Company Gas total$5,015 
Goodwill is not amortized but is subject to an annual impairment test during the fourth quarter of each year, or more frequently if goodwill impairment indicators exist.
Other intangible assets were as follows:
At March 31, 2026At December 31, 2025
Gross
Carrying
Amount		Accumulated
Amortization		Other
Intangible
Assets,
Net		Gross
Carrying
Amount		Accumulated
Amortization		Other
Intangible
Assets,
Net
(in millions)(in millions)
Southern Company
Subject to amortization:
Customer relationships$212 $(190)$22 $212 $(189)$23 
Trade names64 (64)— 64 (64)— 
PPA fair value adjustments390 (193)197 390 (188)202 
Other3 (3)— 3 (3)— 
Total subject to amortization$669 $(450)$219 $669 $(444)$225 
Not subject to amortization:
FCC licenses75 — 75 75 — 75 
Total other intangible assets$744 $(450)$294 $744 $(444)$300 
Southern Power(*)
PPA fair value adjustments$390 $(193)$197 $390 $(188)$202 
Southern Company Gas(*)
Gas marketing services
Customer relationships$156 $(154)$2 $156 $(153)$3 
Trade names26 (26)— 26 (26)— 
Total other intangible assets$182 $(180)$2 $182 $(179)$3 
(*)All subject to amortization.
Amortization associated with other intangible assets was as follows:
Three Months Ended March 31,
20262025
(in millions)
Southern Company(a)
$7 $8 
Southern Power(b)
5 5 
Southern Company Gas
Gas marketing services1 2 
(a)Includes $5 million for the three months ended March 31, 2026 and 2025 recorded as a reduction to operating revenues.
(b)Recorded as a reduction to operating revenues.
Cash, Cash Equivalents, and Restricted Cash
The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that total to the amount shown in the condensed statements of cash flows for the applicable Registrants:
Southern CompanySouthern
Company Gas
(in millions)
At March 31, 2026
Cash and cash equivalents$981 $137 
Restricted cash(*):
Other current assets
6 5 
Total cash, cash equivalents, and restricted cash
$987 $142 
At December 31, 2025
Cash and cash equivalents$1,639 $15 
Restricted cash(*):
Other current assets
1 — 
Total cash, cash equivalents, and restricted cash
$1,640 $15 
(*)For Southern Company Gas, reflects funds held to support letters of credit. For Southern Company, also reflects collateral of $1 million for life insurance and long-term disability insurance, which was included at Southern Holdings.
Natural Gas for Sale
With the exception of Nicor Gas, Southern Company Gas records natural gas inventories on a weighted average cost basis. For any declines in market prices below the weighted average cost considered to be non-temporary, an adjustment is recorded to reduce the value of natural gas inventories to market value. Nicor Gas' natural gas inventory is carried at cost on a LIFO basis. Inventory decrements occurring during the year that are restored prior to year-end are charged to cost of natural gas at the estimated annual replacement cost. Inventory decrements that are not restored prior to year-end are charged to cost of natural gas at the actual LIFO cost of the inventory layers liquidated.
Southern Company Gas recorded no material adjustments to natural gas inventories for either period presented. Nicor Gas' inventory decrement at March 31, 2026 is expected to be restored prior to year end.
v3.26.1
Regulatory Matters
 3 Months Ended
Mar. 31, 2026
Regulated Operations [Abstract]  
Regulatory Matters REGULATORY MATTERS
See Note 2 to the financial statements in Item 8 of the Form 10-K for additional information relating to regulatory matters.
The recovery balances for retail fuel and storm/property damage for the traditional electric operating companies and natural gas cost for Southern Company Gas at March 31, 2026 and December 31, 2025 were as follows:
Recovery/Regulatory ClauseBalance Sheet LocationAt March 31, 2026At December 31, 2025
(in millions)
Alabama Power
Rate ECROther regulatory assets, deferred$200 $146 
NDROther regulatory liabilities, deferred52 60 
Georgia Power
Fuel cost recovery
Receivables – under recovered retail fuel clause revenues
$234 $310 
Deferred under recovered retail fuel clause revenues210 212 
Storm damage recoveryOther regulatory assets, current31 31 
Other regulatory assets, deferred962 880 
Mississippi Power
Fuel cost recovery(*)
Receivables – customer accounts, net$55 $— 
Deferred under recovered retail fuel clause revenues— 40 
Property damage reserveOther regulatory liabilities, deferred57 57 
Southern Company Gas
Natural gas cost recoveryNatural gas cost over recovery$131 $158 
(*)Mississippi Power also has wholesale MRA and Market Based (MB) fuel cost recovery factors. At March 31, 2026 and December 31, 2025, wholesale MRA fuel cost under recovery was $9 million and $6 million, respectively, and was included in customer accounts receivable, net on Mississippi Power's balance sheets. The wholesale MB fuel cost recovery was immaterial for both periods presented.
Alabama Power
Power to the People Act
In December 2025, the Alabama PSC issued a consent order to keep retail rates stable through 2027. On April 2, 2026, the State of Alabama enacted legislation providing that retail base rates established and in place on October 1, 2026 may not be increased before January 1, 2029 for utilities that are regulated by the Alabama PSC and that provide retail electric service. The ultimate outcome of this matter cannot be determined at this time.
Reliability Reserve Accounting Order
In accordance with the notification provided to the Alabama PSC through its annual Rate RSE filing indicating plans to use $60 million of the reliability reserve, Alabama Power utilized $21 million of its reliability reserve during the first quarter 2026 for reliability-related transmission, distribution, and generation expenses. At March 31, 2026, Alabama Power's reliability reserve balance was $163 million.
Environmental Accounting Order
As a result of the planned conversion of Plant Barry Unit 5 from coal to natural gas, the unit's net book value no longer meets the criteria to be considered probable of abandonment, and, in the first quarter 2026, approximately $307 million was reclassified from other utility plant, net to plant in service on Alabama Power's and Southern Company's balance sheets.
Georgia Power
Integrated Resource Plans
Certification Requests
On March 25, 2026, Georgia Interfaith Power & Light, Park Avenue Baptist Church, Unitarian Universalist Church of Savannah, Sierra Club, Adrien Webber, and Southern Alliance for Clean Energy filed a petition with the Fulton County Superior Court appealing the Georgia PSC's December 19, 2025 approval of Georgia Power's request for certification of resources totaling 9,885 MWs (2025 All-Source Certification). The petition requests a reversal of the 2025 All-Source Certification, including a decertification of at least 757 MWs of resources. Georgia Power believes the appeal has no merit; however, the ultimate outcome of this matter cannot be determined at this time.
2025 IRP
On April 23, 2026, pursuant to the final order for Georgia Power's 2025 IRP, Georgia Power filed for approval to issue a request for proposals seeking 2,000 MWs to 6,000 MWs of resources to meet capacity needs in 2032 and 2033. Georgia Power projects a decision from the Georgia PSC regarding issuance in the second quarter 2026. The ultimate outcome of this matter cannot be determined at this time.
Fuel Cost Recovery
On each of March 13, 2026 and April 15, 2026, Georgia Power filed an Interim Fuel Rider (IFR) notification and plan informing the Georgia PSC that Georgia Power's under recovered fuel balance accumulated since May 31, 2023 exceeded $200 million (IFR Threshold), as established in a Georgia PSC stipulation approved in 2023, as of February 28, 2026 and March 31, 2026, respectively. Georgia Power did not propose a fuel cost recovery rate change pursuant to these IFR notifications and plans and is required to monitor and report to the Georgia PSC monthly as long as the under recovered fuel balance is above the IFR Threshold. Georgia Power expects the Georgia PSC to make a final decision on its February 2026 fuel case on May 28, 2026. The ultimate outcome of this matter cannot be determined at this time.
Construction
At March 31, 2026, Georgia Power had recorded approximately $3.7 billion of combined capital costs, excluding AFUDC, for the projects reflected in the table below approved by the Georgia PSC through the 2023 IRP Update and certification requests in September and December 2025 authorized through its 2022 IRP. The total certified
amounts related to these projects are approximately $19.5 billion, excluding AFUDC. The ultimate outcome of these matters cannot be determined at this time.
Resource/Project
Approximate Nameplate Capacity
(MW)
Actual/Projected COD
Projects Under Construction at March 31, 2026
Battery Energy Storage
McGrau Ford Phase 1265Fourth quarter 2026
Twiggs County200Fourth quarter 2027
Wadley260Fourth quarter 2027
Bowen Phase 1
250Fourth quarter 2028
Bowen Phase 2
250Fourth quarter 2029
South Hall250Fourth quarter 2028
Wansley
500Fourth quarter 2028
Yates Phase 1
320Fourth quarter 2028
Yates Phase 2
250Fourth quarter 2028
Thomson500Fourth quarter 2029
Hammond Phase 2193Fourth quarter 2030
McIntosh
250Fourth quarter 2030
Various facilities(a)
372Second quarter 2026 through
fourth quarter 2026
Solar with Battery Energy Storage
Laurens County 200Fourth quarter 2028
Plant Mitchell 150Fourth quarter 2028
Combined Cycle
Plant Bowen Unit 7741Fourth quarter 2029
Plant Bowen Unit 8741Second quarter 2030
Plant McIntosh Unit 12757Fourth quarter 2030
Plant Wansley Unit 10727Fourth quarter 2029
Plant Wansley Unit 11727Second quarter 2030
Combustion Turbine
Plant Yates Unit 8(b)
442Fourth quarter 2026
Plant Yates Unit 9(b)
442Second quarter 2027
Plant Yates Unit 10(b)
442Third quarter 2027
Projects Completed During the Three Months Ended March 31, 2026
Battery Energy Storage
Robins
128March 2026
(a)Subsequent to March 31, 2026, Georgia Power completed construction of the 50-MW Moody battery energy storage facility.
Mississippi Power
Performance Evaluation Plan
On March 16, 2026, Mississippi Power submitted its annual retail PEP Evaluation Report for 2026 to the Mississippi PSC, which affirmed its request filed in November 2025 for a 1.8%, or $20 million, annual increase in revenues, primarily due to increases in investment and depreciation. In accordance with the PEP rate schedule, the increase became effective with the first billing cycle of January 2026, subject to refund. The Mississippi PSC is expected to render a final decision in the second quarter 2026. The ultimate outcome of this matter cannot be determined at this time.
Integrated Resource Plans
On March 9, 2026, in compliance with its IRP requirements, Mississippi Power submitted its mid-point update to its 2024 IRP to the Mississippi PSC, indicating that the retirement dates of Plant Daniel Unit 2 and Plant Watson Unit 4 will extend beyond 2028.
The remaining net book value of Plant Daniel Unit 1 was approximately $124 million at March 31, 2026, and Mississippi Power is continuing to depreciate Plant Daniel Unit 1 using approved rates. Mississippi Power expects to reclassify the net book value remaining at retirement to a regulatory asset to be amortized over a period to be determined by the Mississippi PSC in future proceedings, consistent with a 2020 order. The ultimate outcome of this matter cannot be determined at this time.
Environmental Compliance Overview Plan
On April 14, 2026, the Mississippi PSC approved Mississippi Power's annual ECO Plan filing for 2026, resulting in a $2 million annual increase in revenues effective with the first billing cycle of May 2026.
System Restoration Rider
On March 2, 2026, Mississippi Power submitted its annual SRR filing for 2026 to the Mississippi PSC, indicating no change in retail rates. The filing includes a request to increase the minimum annual SRR accrual from $13.5 million to $13.7 million. The ultimate outcome of this matter cannot be determined at this time.
Reliability Reserve Accounting Order
On March 16, 2026, through its annual PEP Evaluation Report, Mississippi Power notified the Mississippi PSC of its intent to use approximately $8 million of its retail reliability reserve balance during 2026. During the first quarter 2026, Mississippi Power utilized the retail reliability reserve in the amount of $6 million for reliability-related generation, transmission, and distribution expenses. At March 31, 2026, Mississippi Power's retail reliability reserve balance was $52 million. See "Performance Evaluation Plan" herein for information regarding Mississippi Power's annual PEP filing.
v3.26.1
Contingencies
 3 Months Ended
Mar. 31, 2026
Commitments and Contingencies Disclosure [Abstract]  
Contingencies CONTINGENCIES
See Note 3 to the financial statements in Item 8 of the Form 10-K for information relating to various lawsuits and other contingencies.
General Litigation Matters
The Registrants are involved in various matters being litigated and regulatory matters. The ultimate outcome of such pending or potential litigation or regulatory matters against each Registrant and any subsidiaries cannot be determined at this time; however, for current proceedings not specifically reported herein, management does not anticipate that the ultimate liabilities, if any, arising from such current proceedings would have a material effect on such Registrant's financial statements.
The Registrants intend to dispute the allegations raised in and vigorously defend against the pending legal challenges discussed below; however, the ultimate outcome of each of these matters cannot be determined at this time.
Southern Company
In July 2025, a purported class action complaint was filed in the U.S. District Court for the District of Maryland against two nuclear consulting companies and all U.S. commercial nuclear power operators, or affiliated entities, including Southern Company. The purported class of plaintiffs includes all persons employed in nuclear power generation by the defendants, including nuclear operators, nuclear engineers, and nuclear technicians, from May 1, 2003 to the present. The complaint alleges that, since at least May 2003, the nuclear power industry conspired to fix and suppress employee compensation for nuclear power generation employees in violation of federal antitrust law.
Although not named as defendants, other entities are accused of having participated in the plaintiffs' alleged conspiracy. The plaintiffs seek to recover, among other relief, unspecified monetary damages, including treble damages and attorneys' fees, and injunctive relief. In October 2025, Southern Company moved to dismiss the complaint. In November 2025, the plaintiffs filed an amended complaint naming Southern Nuclear, among others, as a defendant. In December 2025, Southern Company and Southern Nuclear filed a motion to dismiss the amended complaint. An adverse outcome could have a material impact on Southern Company's financial statements.
Alabama Power
In 2022, Mobile Baykeeper filed a citizen suit in the U.S. District Court for the Southern District of Alabama alleging that Alabama Power's plan to close the Plant Barry surface impoundment utilizing a closure-in-place methodology violates the Resource Conservation and Recovery Act (RCRA) and regulations governing CCR. Among other relief requested, Mobile Baykeeper sought a declaratory judgment that RCRA and regulations governing CCR were being violated, preliminary and injunctive relief to prevent implementation of Alabama Power's closure plan, and the development of a closure plan that satisfies regulations governing CCR requirements. Later in 2022, Alabama Power filed a motion to dismiss the case. In 2024, the lawsuit was dismissed without prejudice by the U.S. District Court judge. Later in 2024, the U.S. District Court judge denied a motion to reconsider filed by the plaintiff, and the plaintiff filed a notice of appeal in the U.S. Court of Appeals for the Eleventh Circuit challenging the denial of the motion to reconsider the order of dismissal.
In 2023, the EPA issued a Notice of Potential Violations (NOPV) associated with Alabama Power's plan to close the Plant Barry surface impoundment. In 2024, Alabama Power reached a settlement with the EPA resolving two of the three allegations in the NOPV related to the groundwater monitoring system and the emergency action plan at the Plant Barry surface impoundment. The settlement did not resolve the EPA's allegation relating to Alabama Power's plan to close the Plant Barry surface impoundment. Alabama Power has affirmed to the EPA its position that it is in compliance with CCR requirements.
In July 2025, Coosa Riverkeeper filed a citizen suit in the U.S. District Court for the Northern District of Alabama alleging that Alabama Power's closure of the Plant Gadsden surface impoundment utilizing a closure-in-place methodology violates RCRA and regulations governing CCR. Among other relief requested, Coosa Riverkeeper seeks declaratory judgment that Alabama Power is in violation of RCRA and regulations governing CCR, and preliminary and injunctive relief to require Alabama Power to close the CCR unit and operate a groundwater monitoring system in a different manner to satisfy RCRA and the regulations governing CCR requirements. In September 2025, Alabama Power filed a motion to dismiss the citizen suit.
These matters could have a material impact on Alabama Power's and Southern Company's financial statements, including ARO estimates and cash flows. See Note 6 to the financial statements in Item 8 of the Form 10-K for a discussion of Alabama Power's ARO liabilities.
Environmental Remediation
The Southern Company system must comply with environmental laws and regulations governing the handling and disposal of waste and releases of hazardous substances. Under these various laws and regulations, the Southern Company system could incur substantial costs to clean up affected sites. The traditional electric operating companies and the natural gas distribution utilities in Illinois and Georgia have each received authority from their respective state PSCs or other applicable state regulatory agencies to recover approved environmental remediation costs through regulatory mechanisms. These regulatory mechanisms are adjusted annually or as necessary within limits approved by the state PSCs or other applicable state regulatory agencies.
Georgia Power's environmental remediation liability was $14 million at both March 31, 2026 and December 31, 2025. Georgia Power has been designated or identified as a potentially responsible party at sites governed by the Georgia Hazardous Site Response Act and/or by the federal Comprehensive Environmental Response, Compensation, and Liability Act, and assessment and potential cleanup of such sites is expected.
Southern Company Gas' environmental remediation liability was $219 million and $227 million at March 31, 2026 and December 31, 2025, respectively, based on the estimated cost of environmental investigation and remediation at known former manufactured gas plant operating sites.
The ultimate outcome of these matters cannot be determined at this time; however, as a result of the regulatory treatment for environmental remediation expenses described above, the final disposition of these matters is not expected to have a material impact on the financial statements of the applicable Registrants.
v3.26.1
Revenue from Contracts with Customers and Lease Income
 3 Months Ended
Mar. 31, 2026
Revenue from Contract with Customer [Abstract]  
Revenue from Contracts with Customers and Lease Income REVENUE FROM CONTRACTS WITH CUSTOMERS AND LEASE INCOME
Revenue from Contracts with Customers
The Registrants generate revenues from a variety of sources, some of which are not accounted for as revenue from contracts with customers, such as leases, derivatives, and certain cost recovery mechanisms. Included in the wholesale electric revenues of the traditional electric operating companies and Southern Power are revenues associated with affiliate transactions. These revenues are generated through long-term PPAs or short-term energy sales made in accordance with the IIC, as approved by the FERC. Amounts related to these affiliate revenues are eliminated in consolidation for Southern Company. See Note 1 to the financial statements under "Affiliate Transactions" and "Revenues" in Item 8 of the Form 10-K for additional information. See "Lease Income" herein and Note (J) for additional information on revenue accounted for under lease and derivative accounting guidance, respectively.
The following table disaggregates revenue from contracts with customers for the three months ended March 31, 2026 and 2025:
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Three Months Ended March 31, 2026
Operating revenues
Retail electric revenues
Residential$2,003 $773 $1,150 $80 $— $— 
Commercial1,663 477 1,104 82 — — 
Industrial942 414 438 90 — — 
Other31 3 25 3 — — 
Total retail electric revenues4,639 1,667 2,717 255 — — 
Natural gas distribution revenues
Residential1,028 — — — — 1,028 
Commercial253 — — — — 253 
Transportation440 — — — — 440 
Industrial 24 — — — — 24 
Other145 — — — — 145 
Total natural gas distribution revenues1,890 — — — — 1,890 
Wholesale electric revenues
PPA energy revenues496 46 64 4 392 — 
PPA capacity revenues149 18 44 21 83 — 
Non-PPA revenues89 119 44 169 44 — 
Total wholesale electric revenues734 183 152 194 519 — 
Other natural gas revenues
Gas marketing services281 — — — — 281 
Other
3 — — — — 3 
Total other natural gas revenues
284 — — — — 284 
Other revenues493 78 236 15 4 — 
Total revenue from contracts with customers8,040 1,928 3,105 464 523 2,174 
Other revenue sources(*)
357 164 37 8 158 17 
Total operating revenues$8,397 $2,092 $3,142 $472 $681 $2,191 
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Three Months Ended March 31, 2025
Operating revenues
Retail electric revenues
Residential$2,065 $805 $1,186 $74 $— $— 
Commercial1,612 482 1,055 75 — — 
Industrial915 390 444 81 — — 
Other31 3 26 2 — — 
Total retail electric revenues4,623 1,680 2,711 232 — — 
Natural gas distribution revenues
Residential845 — — — — 845 
Commercial199 — — — — 199 
Transportation406 — — — — 406 
Industrial 18 — — — — 18 
Other112 — — — — 112 
Total natural gas distribution revenues1,580 — — — — 1,580 
Wholesale electric revenues
PPA energy revenues415 54 84 3 284 — 
PPA capacity revenues149 28 39 17 82 — 
Non-PPA revenues71 69 9 134 62 — 
Total wholesale electric revenues635 151 132 154 428 — 
Other natural gas revenues
Gas marketing services256 — — — — 256 
Other
4 — — — — 4 
Total other natural gas revenues
260 — — — — 260 
Other revenues493 83 230 20 4 — 
Total revenue from contracts with customers7,591 1,914 3,073 406 432 1,840 
Other revenue sources(*)
184 98 (36)14 135 (1)
Total operating revenues$7,775 $2,012 $3,037 $420 $567 $1,839 
(*)Other revenue sources relate to revenues from customers accounted for as derivatives and leases, alternative revenue programs primarily at Southern Company Gas, and cost recovery mechanisms and revenues (including those related to fuel costs) that meet other scope exceptions for revenues from contracts with customers at the traditional electric operating companies.
Contract Balances
The following table reflects the closing balances of receivables, contract assets, and contract liabilities related to revenues from contracts with customers at March 31, 2026 and December 31, 2025:
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Accounts Receivable
At March 31, 2026$3,083 $649 $1,179 $119 $94 $925 
At December 31, 20253,139 716 1,278 115 132 864 
Contract Assets
At March 31, 2026$338 $5 $196 $— $— $67 
At December 31, 2025294 3 160 — — 67 
Contract Liabilities
At March 31, 2026$257 $9 $76 $2 $1 $— 
At December 31, 2025213 6 75 — 2 — 
Contract assets for Georgia Power primarily relate to unregulated service agreements, where payment is contingent on project completion, and retail customer fixed bill programs, where payment is contingent upon Georgia Power's continued performance and the customer's continued participation in the program over a one-year contract term. Contract liabilities for Georgia Power primarily relate to cash collections recognized in advance of revenue for unregulated service agreements. Southern Company Gas' contract assets relate to work performed on an energy efficiency enhancement and upgrade contract with the U.S. General Services Administration. Southern Company Gas received cash advances totaling approximately $68 million from a third-party financial institution to fund work performed. These advances have been accounted for as long-term debt on the balance sheets. See Note 1 to the financial statements under "Affiliate Transactions" in Item 8 of the Form 10-K for additional information regarding the construction contract. At March 31, 2026 and December 31, 2025, Southern Company's unregulated distributed generation business had contract assets of $69 million and $63 million, respectively, and contract liabilities of $170 million and $132 million, respectively, for outstanding performance obligations, all of which are expected to be satisfied within one year.
Revenues recognized in the three months ended March 31, 2026, which were included in contract liabilities at December 31, 2025, were $55 million for Southern Company, $11 million for Georgia Power, and immaterial for the other Registrants. Contract liabilities are primarily classified as current on the balance sheets as the corresponding revenues are generally expected to be recognized within one year.
Remaining Performance Obligations
Southern Company's subsidiaries may enter into long-term contracts with customers in which revenues are recognized as performance obligations are satisfied over the contract term. For the traditional electric operating companies and Southern Power, these contracts primarily relate to PPAs whereby electricity and generation capacity are provided to a customer. The revenue recognized for the delivery of electricity is variable; however, certain PPAs include a fixed payment for fixed generation capacity over the term of the contract. Southern Company's unregulated distributed generation business also has partially satisfied performance obligations related
to certain fixed price contracts. Revenues from contracts with customers related to these performance obligations remaining at March 31, 2026 are expected to be recognized as follows:
2026 (remaining)2027202820292030Thereafter
(in millions)
Southern Company$875 $679 $452 $412 $416 $3,130 
Alabama Power8 5 4 2 1 6 
Georgia Power48 60 43 22 22 146 
Mississippi Power(*)
49 69 73 12 — — 
Southern Power(*)
270 349 389 393 393 2,978 
Southern Company Gas31 21 — — — — 
(*)Includes performance obligations related to affiliate PPAs with Georgia Power. See Note 1 to the financial statements under "Affiliate Transactions" in Item 8 of the Form 10-K for additional information.
Lease Income
Lease income for the three months ended March 31, 2026 and 2025 was as follows:
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
 (in millions)
Three Months Ended March 31, 2026
Lease income - interest income on sales-type leases$5 $— $— $3 $2 $— 
Lease income - operating leases34 3 7 1 37 9 
Variable lease income79 — — — 87 — 
Total lease income$118 $3 $7 $4 $126 $9 
Three Months Ended March 31, 2025
Lease income - interest income on sales-type leases$6 $— $— $4 $2 $— 
Lease income - operating leases33 2 7 1 37 9 
Variable lease income81 — — — 89 — 
Total lease income$120 $2 $7 $5 $128 $9 
Lease payments received under tolling arrangements and PPAs consist of either scheduled payments or variable payments based on the amount of energy produced by the underlying electric generating units. Lease income related to PPAs is included in wholesale revenues for Alabama Power, Georgia Power, and Southern Power.
v3.26.1
Consolidated Entities and Equity Method Investments
 3 Months Ended
Mar. 31, 2026
Regulated Operations [Abstract]  
Consolidated Entities and Equity Method Investments CONSOLIDATED ENTITIES AND EQUITY METHOD INVESTMENTS
See Note 7 to the financial statements in Item 8 of the Form 10-K for additional information.
Southern Company
At March 31, 2026 and December 31, 2025, Southern Holdings had equity method investments totaling $125 million and $124 million, respectively, primarily related to investments in venture capital funds focused on energy and utility investments. Earnings/losses from these investments were immaterial for all periods presented.
Southern Power
Variable Interest Entities
Southern Power has certain subsidiaries that are determined to be VIEs. Southern Power is considered the primary beneficiary of these VIEs because it controls the most significant activities of the VIEs, including operating and
maintaining the respective assets, and has the obligation to absorb expected losses of these VIEs to the extent of its equity interests.
SP Solar
At March 31, 2026 and December 31, 2025, SP Solar had total assets of $5.1 billion and $5.2 billion, respectively, total liabilities of $361 million and $360 million, respectively, and noncontrolling interests of $899 million and $918 million, respectively. Cash distributions from SP Solar are allocated 67% to Southern Power and 33% to the limited partner in accordance with their partnership interest percentage. Under the terms of the limited partnership agreement, distributions without limited partner consent are limited to available cash and SP Solar is obligated to distribute all such available cash to its partners each quarter. Available cash includes all cash generated in the quarter subject to the maintenance of appropriate operating reserves.
Southern Power consolidates SP Solar, as the primary beneficiary, since it controls the most significant activities of the entity, including operating and maintaining its assets. Certain transfers and sales of the assets in the VIE are subject to partner consent, and the liabilities are non-recourse to the general credit of Southern Power. Liabilities consist of customary working capital items and do not include any long-term debt.
Other Variable Interest Entities
Southern Power has other consolidated VIEs that relate to certain subsidiaries that have either sold noncontrolling interests to tax equity investors or acquired less than a 100% interest from facility developers. These entities are considered VIEs because the arrangements are structured similar to a limited partnership and the noncontrolling members do not have substantive kick-out rights.
At March 31, 2026 and December 31, 2025, the other VIEs had total assets of $1.6 billion, total liabilities of $246 million and $236 million, respectively, and noncontrolling interests of $590 million and $617 million, respectively. Under the terms of the partnership agreements, distributions of all available cash are required each month or quarter and additional distributions require partner consent.
Southern Company Gas
The carrying amounts of Southern Company Gas' equity method investments at March 31, 2026 and December 31, 2025 were as follows:
Investment BalanceAt March 31, 2026At December 31, 2025
(in millions)
SNG$1,190 $1,148 
Other34 34 
Total$1,224 $1,182 
The earnings from Southern Company Gas' equity method investment in SNG were $46 million and $39 million for the three months ended March 31, 2026 and 2025, respectively. The earnings from Southern Company Gas' other equity method investments were immaterial for all periods presented.
v3.26.1
Financing
 3 Months Ended
Mar. 31, 2026
Debt Disclosure [Abstract]  
Financing FINANCING
Bank Credit Arrangements
See Note 8 to the financial statements under "Bank Credit Arrangements" in Item 8 of the Form 10-K for additional information.
At March 31, 2026, committed credit arrangements with banks were as follows:
Expires
Company20262028202920302031TotalUnusedExpires 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 15 
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 — 
SEGCO30 — — — — 30 30 30 
Southern Company$45 $500 $775 $2,300 $5,300 $8,920 $8,909 $45 
(a)Arrangement expiring in 2031 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, Mississippi Power, and Southern 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 March 31, 2026. 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 March 31, 2026.
(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 March 31, 2026. In addition, Southern Power Company had $23 million of letters of credit outstanding under an uncommitted letter of credit facility at March 31, 2026. 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.
As reflected in the table above, in March 2026, (i) Southern Company, Mississippi Power, and Southern Power extended the maturity date of their $3.25 billion combined multi-year credit arrangement from 2030 to 2031, (ii) Southern Company extended the maturity date of its multi-year credit agreement from 2027 to 2028, (iii) Georgia Power extended the maturity date of its multi-year credit arrangement from 2030 to 2031, and (iv) Mississippi Power extended the maturity date of its multi-year credit agreement from 2027 to 2029.
Subject to applicable market conditions, Southern Company and its subsidiaries expect to renew or replace their bank credit arrangements as needed, prior to expiration. In connection therewith, Southern Company and its subsidiaries may extend the maturity dates and/or increase or decrease the lending commitments thereunder.
These bank credit arrangements, as well as the term loan arrangements of the Registrants, Nicor Gas, and SEGCO, contain covenants that limit debt levels and contain cross-acceleration provisions to other indebtedness (including guarantee obligations) that are restricted only to the indebtedness of the individual company. The cross-acceleration provisions to other indebtedness would trigger an event of default if the applicable borrower defaulted on indebtedness, the payment of which was then accelerated. At March 31, 2026, the Registrants, Nicor Gas, and SEGCO were in compliance with all such covenants. None of the bank credit arrangements contain material adverse change clauses at the time of borrowings.
A portion of the unused credit with banks is allocated to provide liquidity support to certain revenue bonds of the traditional electric operating companies and the commercial paper programs of the Registrants, Nicor Gas, and SEGCO. At March 31, 2026, outstanding variable rate demand revenue bonds of the traditional electric operating companies with allocated liquidity support totaled approximately $1.5 billion (comprised of approximately $796 million at Alabama Power, $667 million at Georgia Power, and $58 million at Mississippi Power). In addition, at March 31, 2026, Alabama Power and Georgia Power had approximately $160 million and $325 million, respectively, of fixed rate revenue bonds outstanding that are required to be remarketed within the next 12 months. Alabama Power's $160 million of fixed rate revenue bonds are classified as securities due within one year on its balance sheets as they are not covered by long-term committed credit. All other variable rate demand revenue bonds and fixed rate revenue bonds required to be remarketed within the next 12 months are classified as long-term debt on the balance sheets as a result of available long-term committed credit.
DOE Loan Guarantee Borrowings
On February 20, 2026, pursuant to the loan guarantee program (DOE Loan Guarantee Program) established under Title XVII of the Energy Policy Act of 2005, as amended (Title XVII), Alabama Power entered into (i) a loan guarantee agreement, dated as of February 20, 2026 (Alabama Power LGA), between Alabama Power and the DOE, as guarantor, (ii) a note purchase agreement, dated as of February 20, 2026 (Alabama Power NPA), among Alabama Power, the FFB, and the Secretary of Energy, acting through the DOE, and (iii) future advance promissory notes, each dated February 20, 2026, made by Alabama Power to the FFB (each an Alabama Power FFB Note and, together with the Alabama Power NPA, the Alabama Power FFB Credit Facility Documents). The Alabama Power LGA and the Alabama Power FFB Credit Facility Documents are referred to herein together as the Alabama Power Loan Documents.
In addition, on February 20, 2026, pursuant to the DOE Loan Guarantee Program, Georgia Power entered into (i) a loan guarantee agreement, dated as of February 20, 2026 (Georgia Power LGA and, together with the Alabama Power LGA, the Loan Guarantee Agreements), between Georgia Power and the DOE, as guarantor, (ii) a note purchase agreement, dated as of February 20, 2026 (Georgia Power NPA), among Georgia Power, the FFB, and the Secretary of Energy, acting through the DOE, and (iii) future advance promissory notes, each dated February 20, 2026, made by Georgia Power to the FFB (each a Georgia Power FFB Note and, together with the Georgia Power NPA, the Georgia Power FFB Credit Facility Documents). The Georgia Power LGA and the Georgia Power FFB Credit Facility Documents are referred to herein together as the Georgia Power Loan Documents.
The Alabama Power FFB Credit Facility Documents provide for a multi-advance term loan facility under which Alabama Power may make term loan borrowings through the FFB (Alabama Power Credit Facility). The Georgia Power FFB Credit Facility Documents provide for a multi-advance term loan facility under which Georgia Power may make term loan borrowings through the FFB (Georgia Power Credit Facility and, together with the Alabama Power Credit Facility, the Credit Facilities). Each of Alabama Power and Georgia Power is referred to herein as a Borrower in connection with its applicable Credit Facility.
Proceeds of advances made under each Credit Facility must be used for the purpose of reimbursing the applicable Borrower for a portion (up to 80%) of "eligible project costs" (as defined in the applicable Loan Guarantee Agreement) incurred by such Borrower for projects that are eligible for financing under the terms of the applicable Loan Guarantee Agreement and the DOE Loan Guarantee Program (Eligible Projects). Eligible Projects may include new gas generating units and upgrades associated with existing gas generating units; new transmission lines, substations, and transmission system upgrades; new stand-alone battery energy storage systems; hydropower refurbishment and upgrades; upgrades, uprates, and license extensions for existing nuclear facilities; coal-to-gas conversions; and grid enhancements.
The aggregate amount of advances under the Alabama Power Credit Facility may not exceed approximately $4.1 billion (Alabama Power Maximum Facility Amount). The aggregate amount of advances under the Georgia Power Credit Facility may not exceed approximately $22.4 billion (Georgia Power Maximum Facility Amount and, together with the Alabama Power Maximum Facility Amount, the Maximum Facility Amounts). Each Borrower may request advances under its applicable Credit Facility during an availability period (with respect to each
Borrower, the "availability period") that will continue until the earliest of (i) September 15, 2033, (ii) the date total advances reach the applicable Maximum Facility Amount, or (iii) the termination of the obligation to fund further advances following an event of default under the applicable Loan Guarantee Agreement. In addition, the FFB's obligation to fund advances to Alabama Power will terminate if Alabama Power has failed to request an initial advance by February 20, 2031.
In March 2026, Georgia Power received initial advances under the Georgia Power Credit Facility in an amount of approximately $1.0 billion at an interest rate of 5.041% through the final maturity date of December 10, 2055.
Future advances under each of the Credit Facilities are subject to confirmation of investment grade credit ratings and satisfaction of customary conditions, as well as certification of compliance with the requirements of Title XVII, including accuracy of project-related representation and warranties, delivery of updated project-related information, and evidence of compliance with the prevailing wage requirements of the Davis-Bacon Act of 1931, as amended (DOE Program Requirements), compliance with the Cargo Preference Act of 1954, and certification from the DOE's consulting engineer that proceeds of the advances are used to reimburse for eligible project costs.
All borrowings under each of the Credit Facilities will be full recourse, senior unsecured obligations of the respective Borrower. Alabama Power is not a party to, and has no obligations with respect to, the Georgia Power Credit Facility. Georgia Power is not a party to, and has no obligations with respect to, the Alabama Power Credit Facility.
The final scheduled maturity date for all borrowings under each Credit Facility is December 10, 2055. Each advance will bear interest at a rate equal to the applicable U.S. Treasury rate plus a spread of 0.375%, which rate will be determined at the time of the advance. Principal payments for the Alabama Power Credit Facility are payable in three equal annual installments, beginning on December 10, 2053. Principal payments for the Georgia Power Credit Facility are payable in seven equal annual installments, beginning on December 10, 2049.
Under each of the Loan Guarantee Agreements, the DOE agreed to provide guarantees with respect to the obligations of Alabama Power and Georgia Power under the Alabama Power FFB Credit Facility Documents and Georgia Power FFB Credit Facility Documents, respectively. Under their respective Loan Guarantee Agreements, Alabama Power and Georgia Power are obligated to reimburse the DOE for any amounts the DOE is required to pay with respect to such guarantees. Alabama Power's and Georgia Power's reimbursement obligations to the DOE are full recourse, senior unsecured obligations of the respective Borrower.
Under each Loan Guarantee Agreement, the applicable Borrower is subject to customary affirmative and negative covenants and events of default. In addition, Alabama Power and Georgia Power are subject to project-related reporting requirements and other project-specific covenants and events of default.
Under each Loan Guarantee Agreement, the applicable Borrower will be required to prepay certain amounts outstanding under the applicable Credit Facility if (i) the applicable Borrower takes any action that causes an Eligible Project to cease to be an Eligible Project, (ii) certain "termination events" (as defined in the applicable Loan Guarantee Agreement) occur with respect to any Eligible Project of the applicable Borrower, (iii) eligible project costs recoverable in customer rates of the applicable Borrower are less than 95% of total advances made to the applicable Borrower under the applicable Credit Facility, with such amount tested on the third anniversary of the termination of the applicable availability period, or (iv) the applicable Borrower receives advances for certain preliminary costs and fails to satisfy the DOE Program Requirements. Any mandatory prepayment will be made in quarterly installments and, depending on the size of the required mandatory prepayment, will be payable over a period of one to three years (in the case of Alabama Power) or one to five years (in the case of Georgia Power). Any such mandatory prepayment will be at a prepayment price equal to 100% of the principal amount to be prepaid, plus accrued and unpaid interest to the date of prepayment.
In addition, if a "change of control" (as defined in the applicable Loan Guarantee Agreement) occurs with respect to the applicable Borrower, such Borrower will be required to offer to prepay all outstanding advances under its Credit Facility. Any such prepayment will be made with a make-whole premium or discount, as applicable.
Each Borrower will be permitted to voluntarily prepay all or a portion of any outstanding advances. Any such prepayment will be made with a make-whole premium or discount, as applicable.
Equity Distribution Agreement
See Note 8 to the financial statements under "Equity Distribution Agreement" in Item 8 of the Form 10-K for additional information.
The table below reflects shares of Southern Company common stock sold and settled under separate forward sale contracts with forward purchasers during the three months ended March 31, 2026.
Shares Sold
Initial Forward Price per Share
To be Settled On or Before
Forward Price Per Share SettledShares Issued to SettleSettlement Date
Sold during 2025
3,255,866$89.4692December 31, 2026$89.24433,255,866March 2, 2026
2,314,487$92.7805June 30, 2027$92.87232,314,487March 2, 2026
Sold during 2026
1,467,305$96.3883March 31, 2028N/AN/AN/A
1,896,549$97.5815March 31, 2028N/AN/AN/A
1,903,317$95.5086March 31, 2028N/AN/AN/A
As of March 31, 2026, Southern Company had entered into separate forward sale contracts with forward purchasers for a total of 49,885,779 shares of common stock, all of which had been sold by the forward sellers. Of these shares, 5,570,353 shares were settled during the three months ended March 31, 2026 in the form of shares at the initial forward price adjusted for interest earned and dividends paid from the forward sale date to the settlement date. The net proceeds from the shares settled during the three months ended March 31, 2026 were approximately $506 million.
The total number of shares sold remaining under the forward sale contracts subject to settlement at a future date is 27,398,371. Each initial forward price is subject to adjustment under certain circumstances as specified in the respective forward sales contracts. Southern Company may settle each of the forward transactions in shares, cash, or net shares.
Earnings per Share
For Southern Company, the difference in computing basic and diluted EPS is attributable to awards outstanding under stock-based compensation plans, forward sale contracts pursuant to the equity distribution agreement, convertible senior notes, and equity units. EPS dilution resulting from stock-based compensation plans and the forward sale contracts is determined using the treasury stock method. EPS dilution resulting from the convertible senior notes is determined using the net share settlement method. See "Equity Distribution Agreement" herein and Note 8 to the financial statements under "Convertible Senior Notes," "Equity Distribution Agreement," and "Equity
Units" and Note 12 to the financial statements in Item 8 of the Form 10-K for additional information. Shares used to compute diluted EPS were as follows:
Three Months Ended March 31,
20262025

(in millions)
As reported shares1,124 1,100 
Effect of stock-based compensation4 5 
Diluted shares1,128 1,105 
For both periods presented, an immaterial number of stock-based compensation awards was excluded from the diluted EPS calculation because the awards were anti-dilutive.
For both periods presented, dilution resulting from convertible senior notes and forward sale contracts was immaterial.
v3.26.1
Income Taxes
 3 Months Ended
Mar. 31, 2026
Income Tax Disclosure [Abstract]  
Income Taxes INCOME TAXES
See Note 10 to the financial statements in Item 8 of the Form 10-K for additional tax information.
Cash Paid for Income Taxes
Alabama Power, Georgia Power, and Southern Power have entered into transferability agreements with non-affiliated parties to sell ITCs and PTCs at a discount to the generated credit value in 2024, 2025, and 2026. The discount is recorded as a reduction in tax credits recognized in the financial statements and does not have a material impact on results of operations. Subsequent to March 31, 2026, Alabama Power, Georgia Power, and Southern Power received cash of $6 million, $33 million, and $12 million, respectively, from credits transferred. The Southern Company system continues to explore the ability to efficiently monetize its tax credits through third-party transfer agreements.
During the first three months of 2026, pursuant to certain joint ownership agreements, Georgia Power paid $45 million to the other Vogtle Owners for advanced nuclear PTCs for Plant Vogtle Units 3 and 4. The gain was recognized as an income tax benefit and was immaterial.
Effective Tax Rate
Southern Company's effective tax rate is typically lower than the statutory rate due to employee stock plans' dividend deduction, non-taxable AFUDC equity at the traditional electric operating companies, flowback of excess deferred income taxes at the regulated utilities, and federal income tax benefits from ITCs and PTCs.
Details of significant changes in the effective tax rate for the applicable Registrants are provided herein.
Southern Company
Southern Company's effective tax rate was 14.5% for the three months ended March 31, 2026 compared to 18.1% for the corresponding period in 2025. The effective tax rate decrease was primarily due to an increase in federal PTCs at Southern Power and an increase in amortization of federal PTCs at Georgia Power.
Georgia Power
Georgia Power's effective tax rate was 11.9% for the three months ended March 31, 2026 compared to 14.2% for the corresponding period in 2025. The effective tax rate decrease was primarily due to an increase in amortization of federal PTCs.
Southern Power
Southern Power's effective tax rate benefit was (82.6)% for the three months ended March 31, 2026 compared to (5.3)% for the corresponding period in 2025. The effective tax rate benefit increase was primarily due to an increase in federal PTCs resulting from Southern Power's purchase of the noncontrolling membership interests in the SP Wind tax equity partnership, as well as a change in pre-tax earnings attributable to Southern Power, including the impact of accelerated depreciation related to wind repowering projects. See Note (K) under "Southern Power – Wind Repowering Projects" and Notes 5 and 15 to the financial statement under "Depreciation and Amortization – Southern Power" and "Southern Power – Purchase of Renewable Facility Interests," respectively, in Item 8 of the Form 10-K for additional information.
v3.26.1
Retirement Benefits
 3 Months Ended
Mar. 31, 2026
Retirement Benefits [Abstract]  
Retirement Benefits RETIREMENT BENEFITS
The Southern Company system has a qualified defined benefit, trusteed, pension plan covering substantially all employees, with the exception of employees at PowerSecure. The qualified pension plan is funded in accordance with requirements of the Employee Retirement Income Security Act of 1974, as amended. No mandatory contributions to the qualified pension plan are anticipated for the year ending December 31, 2026. The Southern Company system also provides certain non-qualified defined benefits for a select group of management and highly compensated employees, which are funded on a cash basis. In addition, the Southern Company system provides certain medical care and life insurance benefits for retired employees through other postretirement benefit plans. The traditional electric operating companies fund other postretirement trusts to the extent required by their respective regulatory commissions.
See Note 11 to the financial statements in Item 8 of the Form 10-K for additional information.
On each Registrant's condensed statements of income, the service cost component of net periodic benefit costs is included in other operations and maintenance expenses and all other components of net periodic benefit costs are included in other income (expense), net. Components of the net periodic benefit costs for the three months ended March 31, 2026 and 2025 are presented in the following tables.
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Three Months Ended March 31, 2026
Pension Plans
Service cost$69 $15 $17 $3 $2 $7 
Interest cost162 38 47 7 2 11 
Expected return on plan assets(322)(79)(99)(15)(4)(21)
Amortization:
Prior service costs— — — — — (1)
Regulatory asset— — — — — 3 
Net loss18 5 6 1 — — 
Net periodic pension income$(73)$(21)$(29)$(4)$— $(1)
Postretirement Benefits
Service cost$3 $1 $1 $— $— $— 
Interest cost16 4 6 1 — 2 
Expected return on plan assets(23)(9)(8)(1)— (2)
Amortization:
Prior service costs1 — — — — — 
Net gain(2)— — — — (2)
Net periodic postretirement benefit income$(5)$(4)$(1)$— $— $(2)
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Three Months Ended March 31, 2025
Pension Plans
Service cost$66 $15 $16 $3 $1 $7 
Interest cost166 39 49 7 2 11 
Expected return on plan assets(320)(78)(99)(15)(4)(22)
Amortization:
Prior service costs— — — — — (1)
Regulatory asset— — — — — 4 
Net loss9 2 4 1 1 — 
Net periodic pension income$(79)$(22)$(30)$(4)$— $(1)
Postretirement Benefits
Service cost$3 $1 $1 $— $— $— 
Interest cost17 4 6 1 — 2 
Expected return on plan assets(23)(9)(8)— — (2)
Amortization:
Prior service costs1 — — — — — 
Regulatory asset— — — — — 2 
Net gain(3)— — (1)— (2)
Net periodic postretirement benefit income$(5)$(4)$(1)$— $— $— 
v3.26.1
Fair Value Measurements
 3 Months Ended
Mar. 31, 2026
Fair Value Disclosures [Abstract]  
Fair Value Measurements FAIR VALUE MEASUREMENTS
At March 31, 2026, assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows:
Fair Value Measurements Using
At March 31, 2026Quoted Prices
in Active
Markets for
Identical
Assets
(Level 1)		Significant
Other
Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)		Net Asset
Value as a
Practical
Expedient
(NAV)		Total
(in millions)
Southern Company
Assets:
Energy-related derivatives(a)
$2 $76 $— $— $78 
Interest rate derivatives— 7 — — 7 
Foreign currency derivatives— 5 — — 5 
Investments in trusts:(b)
Domestic equity884 259 — — 1,143 
Foreign equity177 231 — — 408 
U.S. Treasury and government agency securities— 390 — — 390 
Municipal bonds— 50 — — 50 
Pooled funds – fixed income— 4 — — 4 
Corporate bonds— 529 — — 529 
Mortgage- and asset-backed securities — 108 — — 108 
Private equity— — — 195 195 
Cash and cash equivalents1 — — — 1 
Other63 3 — 9 75 
Investments, available-for-sale:
U.S. Treasury and government agency securities2 12 — — 14 
Municipal bonds— 1 — — 1 
Corporate bonds— 3 — — 3 
Mortgage- and asset-backed securities— 4 — — 4 
Cash equivalents486 15 — — 501 
Other investments10 39 8 — 57 
Other— — 10 — 10 
Total$1,625 $1,736 $18 $204 $3,583 
Liabilities:
Energy-related derivatives(a)
$9 $151 $— $— $160 
Interest rate derivatives— 191 — — 191 
Foreign currency derivatives— 50 — — 50 
Contingent consideration— — 11 — 11 
Other— 13 11 — 24 
Total$9 $405 $22 $— $436 
Fair Value Measurements Using
At March 31, 2026Quoted Prices
in Active
Markets for
Identical
Assets
(Level 1)		Significant
Other
Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)		Net Asset
Value as a
Practical
Expedient
(NAV)		Total
(in millions)
Alabama Power
Assets:
Energy-related derivatives$— $25 $— $— $25 
Nuclear decommissioning trusts:(b)
Domestic equity502 248 — — 750 
Foreign equity177 — — — 177 
U.S. Treasury and government agency securities— 15 — — 15 
Municipal bonds— 1 — — 1 
Corporate bonds— 317 — — 317 
Mortgage- and asset-backed securities— 30 — — 30 
Private equity— — — 195 195 
Other13 1 — 9 23 
Cash equivalents9 15 — — 24 
Other investments— 39 — — 39 
Total$701 $691 $— $204 $1,596 
Liabilities:
Energy-related derivatives$— $48 $— $— $48 
Georgia Power
Assets:
Energy-related derivatives$— $25 $— $— $25 
Nuclear decommissioning trusts:(b)
Domestic equity382 1 — — 383 
Foreign equity— 229 — — 229 
U.S. Treasury and government agency securities— 375 — — 375 
Municipal bonds— 49 — — 49 
Corporate bonds— 212 — — 212 
Mortgage- and asset-backed securities— 78 — — 78 
Other50 2 — — 52 
Cash equivalents8 — — — 8 
Total$440 $971 $— $— $1,411 
Liabilities:
Energy-related derivatives$— $49 $— $— $49 
Mississippi Power
Assets:
Energy-related derivatives$— $19 $— $— $19 
Liabilities:
Energy-related derivatives$— $38 $— $— $38 
Fair Value Measurements Using
At March 31, 2026Quoted Prices
in Active
Markets for
Identical
Assets
(Level 1)		Significant
Other
Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)		Net Asset
Value as a
Practical
Expedient
(NAV)		Total
(in millions)
Southern Power
Assets:
Energy-related derivatives$— $4 $— $— $4 
Foreign currency derivatives— 5 — — 5 
Other— — 10 — 10 
Total$— $9 $10 $— $19 
Liabilities:
Energy-related derivatives$— $3 $— $— $3 
Contingent consideration— — 11 — 11 
Other— 13 11 — 24 
Total$— $16 $22 $— $38 
Southern Company Gas
Assets:
Energy-related derivatives(a)
$2 $3 $— $— $5 
Non-qualified deferred compensation trusts:
Domestic equity— 10 — — 10 
Foreign equity— 2 — — 2 
Pooled funds – fixed income— 4 — — 4 
Cash and cash equivalents1 — — — 1 
Cash equivalents121 — — — 121 
Total$124 $19 $— $— $143 
Liabilities:
Energy-related derivatives(a)
$9 $13 $— $— $22 
Interest rate derivatives— 55 — — 55 
Total$9 $68 $— $— $77 
(a)Excludes cash collateral of $22 million.
(b)Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. See Note 6 to the financial statements under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information.
Southern Company, Alabama Power, and Georgia Power continue to elect the option to fair value investment securities held in the nuclear decommissioning trust funds. The fair value of the funds, including reinvested interest and dividends and excluding the funds' expenses, increased (decreased) by the amounts shown in the table below for
the three months ended March 31, 2026 and 2025. The changes were recorded as a change to the regulatory assets and liabilities related to AROs for Georgia Power and Alabama Power, respectively.
Three Months Ended March 31,
Fair value increases (decreases)20262025
(in millions)
Southern Company $(44)$(6)
Alabama Power (30)(13)
Georgia Power(14)7 
Valuation Methodologies
The energy-related derivatives primarily consist of exchange-traded and over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and occasionally, implied volatility of interest rate options. The fair value of cross-currency swaps reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future foreign currency exchange rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and discount rates. The interest rate derivatives and cross-currency swaps are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note (J) for additional information on how these derivatives are used.
For fair value measurements of the investments within the nuclear decommissioning trusts and the non-qualified deferred compensation trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available.
The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. See Note 6 to the financial statements under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information.
Southern Company's investments, available for sale relate to a wholly-owned subsidiary that insures various risk exposures of Southern Company and its subsidiaries. Corporate and municipal bonds, government agency securities, and commercial paper are valued using pricing models maximizing the use of observable inputs for similar securities, including basing value on yields currently available on comparable securities of issues with similar credit ratings. Mortgage- and asset-backed securities are valued through an analysis of the underlying assets and a review of the documentation, including financials, the manager's valuation methodology in valuing their underlying assets, the types of assets and risks involved, and the investor's exit and termination parameters.
Southern Power has contingent payment obligations related to two of its acquisitions whereby it is primarily obligated to make generation-based payments to the seller, commencing at the commercial operation of each facility
and continuing through 2026 and 2036, respectively. The obligations are primarily categorized as Level 3 under Fair Value Measurements as the fair value is determined using significant unobservable inputs for the forecasted facility's generation in MW-hours, as well as other inputs such as a fixed dollar amount per MW-hour, and a discount rate. The fair value of the obligations reflects the net present value of expected payments and any periodic change arising from forecasted generation is expected to be immaterial.
Southern Power also has payment obligations through 2040 whereby it must reimburse the transmission owners for interconnection facilities and network upgrades constructed to support connection of a Southern Power generating facility to the transmission system. The obligations are categorized as Level 2 under Fair Value Measurements as the fair value is determined using observable inputs for the contracted amounts and reimbursement period, as well as a discount rate. The fair value of the obligations reflects the net present value of expected payments.
"Other investments" primarily includes investments traded in the open market that have maturities greater than 90 days, which are categorized as Level 2 under Fair Value Measurements and are comprised of corporate bonds, bank certificates of deposit, treasury bonds, and/or agency bonds.
At March 31, 2026, the fair value measurements of private market investments held in Alabama Power's nuclear decommissioning trusts that are calculated at net asset value per share (or its equivalent) as a practical expedient totaled $204 million and unfunded commitments related to the private market investments totaled $73 million. Private market investments include high-quality private equity funds across several market sectors, funds that invest in real estate assets, and a private credit fund. Private market funds do not have redemption rights. Distributions from these funds will be received as the underlying investments in the funds are liquidated.
At March 31, 2026, other financial instruments for which the carrying amount did not equal fair value were as follows:
Southern
   Company(*)
Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power
Southern
Company
   Gas(*)
(in billions)
Long-term debt, including securities due within one year:
Carrying amount$72.1 $12.0 $21.7 $1.8 $2.9 $9.3 
Fair value66.5 10.7 20.2 1.7 2.8 8.3 
(*)The carrying amount of Southern Company Gas' long-term debt includes fair value adjustments from the effective date of the 2016 merger with Southern Company. Southern Company Gas amortizes the fair value adjustments over the remaining lives of the respective bonds, the latest being through 2043.
The fair values are determined using Level 2 measurements and are based on quoted market prices for the same or similar issues or on the current rates available to the Registrants.
v3.26.1
Derivatives
 3 Months Ended
Mar. 31, 2026
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Derivatives DERIVATIVES
The Registrants are exposed to market risks, including commodity price risk, interest rate risk, weather risk, and occasionally foreign currency exchange rate risk. To manage the volatility attributable to these exposures, each company nets its exposures, where possible, to take advantage of natural offsets and enters into various derivative transactions for the remaining exposures pursuant to each company's policies in areas such as counterparty exposure and risk management practices. Each company's policy is that derivatives are to be used primarily for hedging purposes and mandates strict adherence to all applicable risk management policies. Derivative positions are monitored using techniques including, but not limited to, market valuation, value at risk, stress testing, and sensitivity analysis. Derivative instruments are recognized at fair value in the balance sheets as either assets or liabilities and are presented on a net basis. See Note (I) for additional fair value information. In the statements of cash flows, any cash impacts of settled energy-related and interest rate derivatives are recorded as operating activities. Any cash impacts of settled foreign currency derivatives are classified as operating or financing activities to correspond with the classification of the hedged interest or principal, respectively. See Note 1 to the financial statements under "Financial Instruments" in Item 8 of the Form 10-K for additional information.
Energy-Related Derivatives
The Subsidiary Registrants enter into energy-related derivatives to hedge exposures to electricity, natural gas, and other fuel price changes. However, due to cost-based rate regulations and other various cost recovery mechanisms, the traditional electric operating companies and the natural gas distribution utilities have limited exposure to market volatility in energy-related commodity prices. Each of the traditional electric operating companies and certain of the natural gas distribution utilities manage fuel-hedging programs, implemented per the guidelines of their respective state PSCs or other applicable state regulatory agencies, through the use of financial derivative contracts, which are expected to continue to mitigate price volatility. The traditional electric operating companies (with respect to wholesale generating capacity) and Southern Power have limited exposure to market volatility in energy-related commodity prices because their long-term sales contracts shift substantially all fuel cost responsibility to the purchaser. However, the traditional electric operating companies and Southern Power may be exposed to market volatility in energy-related commodity prices to the extent any uncontracted capacity is used to sell electricity. Southern Company Gas retains exposure to price changes that can, in a volatile energy market, be material and can adversely affect its results of operations.
Southern Company Gas also enters into weather derivative contracts as economic hedges in the event of warmer-than-normal weather. Exchange-traded options are carried at fair value, with changes reflected in natural gas revenues. Non-exchange-traded options are accounted for using the intrinsic value method. Changes in the intrinsic value for non-exchange-traded contracts are reflected in natural gas revenues.
Energy-related derivative contracts are accounted for under one of three methods:
•Regulatory Hedges – Energy-related derivative contracts designated as regulatory hedges relate primarily to the traditional electric operating companies' and the natural gas distribution utilities' fuel-hedging programs, where gains and losses are initially recorded as regulatory liabilities and assets, respectively, and then are included in fuel expense as the underlying fuel is used in operations and ultimately recovered through an approved cost recovery mechanism.
•Cash Flow Hedges – Gains and losses on energy-related derivatives designated as cash flow hedges (which are mainly used to hedge anticipated purchases and sales) are initially deferred in accumulated OCI before being recognized in the statements of income in the same period and in the same income statement line item as the earnings effect of the hedged transactions.
•Not Designated – Gains and losses on energy-related derivative contracts that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred.
Some energy-related derivative contracts require physical delivery as opposed to financial settlement, and this type of derivative is both common and prevalent within the electric and natural gas industries. When an energy-related derivative contract is settled physically, any cumulative unrealized gain or loss is reversed and the contract price is recognized in the respective line item representing the actual price of the underlying goods being delivered.
At March 31, 2026, the net volume of energy-related derivative contracts for natural gas positions, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows:
Net
Purchased
mmBtu		Longest
Hedge
Date		Longest
Non-Hedge
Date
(in millions)
Southern Company(*)
46920302029
Alabama Power14520292026
Georgia Power13220282026
Mississippi Power11220302026
Southern Power720302026
Southern Company Gas(*)
7320282029
(*)Southern Company Gas' derivative instruments include both long and short natural gas positions. A long position is a contract to purchase natural gas and a short position is a contract to sell natural gas. Southern Company Gas' volume represents the net of 80 million mmBtu long natural gas positions and 7 million mmBtu short natural gas positions at March 31, 2026, which is also included in Southern Company's total volume.
In addition to the volumes discussed above, the traditional electric operating companies and Southern Power enter into physical natural gas supply contracts that provide the option to sell back excess natural gas due to operational constraints. The maximum expected volume of natural gas subject to such a feature is 13 million mmBtu for Southern Company, which includes 3 million mmBtu for Alabama Power, 5 million mmBtu for Georgia Power, 2 million mmBtu for Mississippi Power, and 3 million mmBtu for Southern Power.
For cash flow hedges of energy-related derivatives, the estimated pre-tax gains (losses) expected to be reclassified from accumulated OCI to earnings for the 12-month period ending March 31, 2027 are immaterial for Southern Company, Southern Power, and Southern Company Gas.
Interest Rate Derivatives
Southern Company and certain subsidiaries may enter into interest rate derivatives to hedge exposure to changes in interest rates. Derivatives related to existing variable rate securities or forecasted transactions are accounted for as cash flow hedges where the derivatives' fair value gains or losses are recorded in OCI and are reclassified into earnings at the same time and presented on the same income statement line item as the earnings effect of the hedged transactions. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings on the same income statement line item. Fair value gains or losses on derivatives that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred.
At March 31, 2026, the following interest rate derivatives were outstanding:
Notional
Amount		Weighted
Average Interest
Rate Paid		Interest
Rate
Received		Hedge
Maturity
Date
Fair Value
Gain (Loss) at
March 31, 2026
 (in millions)   (in millions)
Fair Value Hedges of Existing Debt
Southern Company parent$400 
1-day SOFR + 0.80%
1.75%March 2028$(20)
Southern Company parent1,000 
1-day SOFR + 2.48%
3.70%April 2030(103)
Southern Company parent565 
1-day SOFR + 1.56%
6.50%March 2045(6)
Southern Company Gas500 
1-day SOFR + 0.49%
1.75%January 2031(55)
Southern Company$2,465 $(184)
For cash flow hedges of interest rate derivatives, the estimated pre-tax gains (losses) expected to be reclassified from accumulated OCI to interest expense for the 12-month period ending March 31, 2027 are immaterial for Southern Company, the traditional electric operating companies, and Southern Company Gas. Deferred gains and losses related to interest rate derivatives are expected to be amortized into earnings through 2054 for Southern Company, Georgia Power, and Mississippi Power, 2052 for Alabama Power, and 2046 for Southern Company Gas.
Foreign Currency Derivatives
Southern Company and certain subsidiaries, including Southern Power, may enter into foreign currency derivatives to hedge exposure to changes in foreign currency exchange rates, such as that arising from the issuance of debt denominated in a currency other than U.S. dollars. Derivatives related to forecasted transactions are accounted for as cash flow hedges where the derivatives' fair value gains or losses are recorded in OCI and are reclassified into earnings at the same time and on the same income statement line as the earnings effect of the hedged transactions, including foreign currency gains or losses arising from changes in the U.S. currency exchange rates. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings on the same income statement line item, including foreign currency gains or losses arising from changes in the U.S. currency exchange rates. Southern Company has elected to exclude the cross-currency basis spread from the assessment of effectiveness in the fair value hedges of its foreign currency risk and record any difference between the change in the fair value of the excluded components and the amounts recognized in earnings as a component of OCI.
At March 31, 2026, the following foreign currency derivatives were outstanding:
Pay
Notional		Pay
Rate		Receive
Notional		Receive
Rate		Hedge
Maturity Date
Fair Value
Gain (Loss) at
March 31, 2026
(in millions)(in millions)(in millions)
Cash Flow Hedges of Existing Debt
Southern Power$564 3.78%€500 1.85%June 2026$5 
Fair Value Hedges of Existing Debt
Southern Company parent1,476 3.39%1,250 1.88%September 2027(50)
Southern Company$2,040 €1,750 $(45)
For cash flow hedges of foreign currency derivatives, the estimated pre-tax gains expected to be reclassified from accumulated OCI to earnings for the 12-month period ending March 31, 2027 are immaterial for Southern Power.
Derivative Financial Statement Presentation and Amounts
The Registrants enter into derivative contracts that may contain certain provisions that permit intra-contract netting of derivative receivables and payables for routine billing and offsets related to events of default and settlements. Southern Company and certain subsidiaries also utilize master netting agreements to mitigate exposure to counterparty credit risk. The fair value amounts of derivative assets and liabilities on the balance sheets are presented net to the extent that there are netting arrangements or similar agreements with the counterparties.
The fair value of energy-related derivatives, interest rate derivatives, and foreign currency derivatives was reflected as either assets or liabilities in the balance sheets (included in "Other" or shown separately as "Risk Management Activities") as follows:
At March 31, 2026At December 31, 2025
Derivative Category and Balance Sheet LocationAssetsLiabilitiesAssetsLiabilities
(in millions)
Southern Company
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current
$35 $91 $24 $64 
Non-current
34 56 31 35 
Total derivatives designated as hedging instruments for regulatory purposes69 147 55 99 
Derivatives designated as hedging instruments in cash flow and fair value hedges
Energy-related derivatives:
Current2 8 1 6 
Non-current2 — 2 1 
Interest rate derivatives:
Current7 49 8 48 
Non-current— 142 — 139 
Foreign currency derivatives:
Current5 22 17 22 
Non-current— 28 4 — 
Total derivatives designated as hedging instruments in cash flow and fair value hedges16 249 32 216 
Energy-related derivatives not designated as hedging instruments
Current5 5 6 6 
Gross amounts recognized90 401 93 321 
Gross amounts offset(a)
(53)(75)(21)(54)
Net amounts recognized in the Balance Sheets(b)
$37 $326 $72 $267 
Alabama Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current$12 $26 $9 $18 
Non-current13 22 10 13 
Total derivatives designated as hedging instruments for regulatory purposes25 48 19 31 
Gross amounts offset(23)(23)(13)(13)
Net amounts recognized in the Balance Sheets$2 $25 $6 $18 
At March 31, 2026At December 31, 2025
Derivative Category and Balance Sheet LocationAssetsLiabilitiesAssetsLiabilities
(in millions)
Georgia Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current$13 $32 $7 $23 
Non-current9 17 10 10 
Total derivatives designated as hedging instruments for regulatory purposes22 49 17 33 
Energy-related derivatives not designated as hedging instruments
Current
3 — 1 — 
Gross amounts recognized25 49 18 33 
Gross amounts offset(21)(21)(14)(14)
Net amounts recognized in the Balance Sheets$4 $28 $4 $19 
Mississippi Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current$7 $21 $3 $15 
Non-current12 17 11 12 
Total derivatives designated as hedging instruments for regulatory purposes19 38 14 27 
Gross amounts offset(18)(18)(13)(13)
Net amounts recognized in the Balance Sheets$1 $20 $1 $14 
Southern Power
Derivatives designated as hedging instruments in cash flow hedges
Energy-related derivatives:
Current$1 $2 $1 $1 
Non-current2 — 2 — 
Foreign currency derivatives:
Current5 — 17 — 
Total derivatives designated as hedging instruments in cash flow hedges
8 2 20 1 
Energy-related derivatives not designated as hedging instruments
Energy-related derivatives:
Current
1 1 1 — 
Gross amounts recognized9 3 21 1 
Gross amounts offset(1)(1)— — 
Net amounts recognized in the Balance Sheets$8 $2 $21 $1 
At March 31, 2026At December 31, 2025
Derivative Category and Balance Sheet LocationAssetsLiabilitiesAssetsLiabilities
(in millions)
Southern Company Gas
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current
$3 $12 $5 $8 
Derivatives designated as hedging instruments in cash flow and fair value hedges
Energy-related derivatives:
Current1 6 — 5 
Non-current— — — 1 
Interest rate derivatives:
Current— 12 — 13 
Non-current— 43 — 46 
Total derivatives designated as hedging instruments in cash flow and fair value hedges1 61 — 65 
Energy-related derivatives not designated as hedging instruments
Current1 4 4 6 
Gross amounts recognized5 77 9 79 
Gross amounts offset(a)
10 (12)19 (14)
Net amounts recognized in the Balance Sheets(b)
$15 $65 $28 $65 
(a)Gross amounts offset includes cash collateral held on deposit in broker margin accounts of $22 million and $33 million at March 31, 2026 and December 31, 2025, respectively.
(b)Net amounts of derivative instruments outstanding exclude immaterial premium and intrinsic value associated with weather derivatives at March 31, 2026 and December 31, 2025.
At March 31, 2026 and December 31, 2025, the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows:
Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheets
Derivative Category and Balance Sheet
Location		Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern Company Gas
 (in millions)
At March 31, 2026:
Energy-related derivatives:
Other regulatory assets, current$(60)$(16)$(20)$(14)$(10)
Other regulatory assets, deferred(23)(10)(8)(5)— 
Other regulatory liabilities, current4 2 1 — 1 
Other regulatory liabilities, deferred1 1 — — — 
Total energy-related derivative gains (losses)$(78)$(23)$(27)$(19)$(9)
At December 31, 2025:
Energy-related derivatives:
Other regulatory assets, current$(48)$(13)$(17)$(12)$(6)
Other regulatory assets, deferred(8)(5)(1)(2)— 
Other regulatory liabilities, current7 4 1 — 2 
Other regulatory liabilities, deferred4 2 1 1 — 
Total energy-related derivative gains (losses)$(45)$(12)$(16)$(13)$(4)
For the three months ended March 31, 2026 and 2025, the pre-tax effects of cash flow and fair value hedge accounting on accumulated OCI for the applicable Registrants were as follows:
Gain (Loss) From Derivatives Recognized in OCIThree Months Ended March 31,
20262025
(in millions)
Southern Company
Cash flow hedges:
Energy-related derivatives$10 $19 
Interest rate derivatives— (2)
Foreign currency derivatives(12)19 
Fair value hedges(*):
Foreign currency derivatives(1)(16)
Total$(3)$20 
Georgia Power
Cash flow hedges:
Interest rate derivatives$— $(2)
Southern Power
Cash flow hedges:
Energy-related derivatives$2 $3 
Foreign currency derivatives(12)19 
Total$(10)$22 
Southern Company Gas
Cash flow hedges:
Energy-related derivatives$8 $16 
(*)Represents amounts excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI.
For the three months ended March 31, 2026 and 2025, the pre-tax effects of cash flow and fair value hedge accounting on income were as follows:
Gain (Loss)
Statements of Income Location
Derivative Category
Three Months Ended March 31,
20262025
(in millions)
Southern Company
Fuel
Energy-related cash flow hedges
$3 $1 
Cost of natural gas
Energy-related cash flow hedges
10 (1)
Interest expense, net of amounts capitalized
Interest rate cash flow hedges
(2)(2)
Foreign currency cash flow hedges
(3)(3)
Interest rate fair value hedges
20 40 
Other income (expense), net
Foreign currency cash flow hedges
(13)21 
Foreign currency fair value hedges
(32)40 
Amount excluded from effectiveness testing recognized in earnings1 16 
Southern Power
Fuel
Energy-related cash flow hedges
$3 $1 
Interest expense, net of amounts capitalized
Foreign currency cash flow hedges
(3)(3)
Other income (expense), net
Foreign currency cash flow hedges
(13)21 
Southern Company Gas
Cost of natural gas
Energy-related cash flow hedges
$10 $(1)
Interest expense, net of amounts capitalized
Interest rate fair value hedges
29 17 
At March 31, 2026 and December 31, 2025, the following amounts were recorded on the balance sheets related to cumulative basis adjustments for fair value hedges:
Carrying Amount of the Hedged
Item		Cumulative Amount of Fair Value
Hedging Adjustment included in
Carrying Amount of the Hedged
Item
Balance Sheet Location of Hedged ItemsAt March 31, 2026At December 31, 2025At March 31, 2026At December 31, 2025
(in millions)
Southern Company
Long-term debt$(3,710)$(3,742)$158 $156 
Southern Company Gas
Long-term debt$(446)$(446)$52 $51 
Contingent Features
The Registrants do not have any credit arrangements that would require material changes in payment schedules or terminations as a result of a credit rating downgrade. There are certain derivatives that could require collateral, but not accelerated payment, in the event of various credit rating changes of certain Southern Company subsidiaries. Generally, collateral may be provided by a Southern Company guaranty, letter of credit, or cash. At March 31, 2026, the Registrants had no collateral posted with derivative counterparties to satisfy these arrangements.
For Southern Company, the fair value of foreign currency derivative liabilities and interest rate derivative liabilities with contingent features, and the maximum potential collateral requirements arising from the credit-risk-related contingent features at a rating below BBB- and/or Baa3, was $26 million at March 31, 2026. For Southern Power,
there were no foreign currency derivative liabilities with contingent features or associated collateral requirements arising from the credit-risk-related contingent features at a rating below BBB- and/or Baa3 at March 31, 2026. For the traditional electric operating companies and Southern Power, energy-related derivative liabilities with contingent features and the maximum potential collateral requirements arising from the credit-risk-related contingent features, at a rating below BBB- and/or Baa3, were immaterial at March 31, 2026. The maximum potential collateral requirements arising from the credit-risk-related contingent features for the traditional electric operating companies and Southern Power include certain agreements that could require collateral in the event that one or more Southern Company power pool participants has a credit rating change to below investment grade.
Alabama Power and Southern Power maintain accounts with certain regional transmission organizations to facilitate financial derivative transactions and they may be required to post collateral based on the value of the positions in these accounts and the associated margin requirements. At March 31, 2026, cash collateral posted in these accounts was immaterial for Alabama Power and Southern Power. Southern Company Gas maintains accounts with brokers or the clearing houses of certain exchanges to facilitate financial derivative transactions. Based on the value of the positions in these accounts and the associated margin requirements, Southern Company Gas may be required to deposit cash into these accounts, which are netted with energy-related derivatives recognized in the balance sheets.
The Registrants are exposed to losses related to financial instruments in the event of counterparties' nonperformance. The Registrants generally enter into agreements and material transactions with counterparties that have investment grade credit ratings by Moody's, S&P, or Fitch or with counterparties who have posted collateral to cover potential credit exposure. The Registrants have also established risk management policies and controls to determine and monitor the creditworthiness of counterparties in order to mitigate their exposure to counterparty credit risk.
Southern Company Gas uses established credit policies to determine and monitor the creditworthiness of counterparties, including requirements to post collateral or other credit security, as well as the quality of pledged collateral. Collateral or credit security is most often in the form of cash or letters of credit from an investment-grade financial institution, but may also include cash or U.S. government securities held by a trustee. Prior to entering a physical transaction, Southern Company Gas assigns its counterparties an internal credit rating and credit limit based on the counterparties' Moody's, S&P, and Fitch ratings, commercially available credit reports, and audited financial statements. Southern Company Gas may require counterparties to pledge additional collateral when deemed necessary.
The Registrants do not anticipate a material adverse effect on their respective financial statements as a result of counterparty nonperformance.
v3.26.1
Acquisitions and Dispositions
 3 Months Ended
Mar. 31, 2026
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]  
Acquisitions and Dispositions ACQUISITIONS AND DISPOSITIONS
See Note 15 to the financial statements in Item 8 of the Form 10-K for additional information.
Southern Power
Construction Projects
During the three months ended March 31, 2026, Southern Power completed construction of and placed in service the 200-MW first phase and continued construction of the 180-MW second phase and 132-MW third phase of the Millers Branch solar facility. At March 31, 2026, the total cost of construction incurred for the Millers Branch
project was $692 million, of which $387 million remains in CWIP. The ultimate outcome of these matters cannot be determined at this time.
Project
Facility		Resource
Approximate
Nameplate Capacity
(MW)
LocationActual/Projected
COD		PPA
Contract
Period
Projects Under Construction at March 31, 2026
Millers Branch
Phase II
Solar180Haskell County, TXSecond quarter 202615 years
Phase III
Solar
132Haskell County, TX
Fourth quarter 2026
15 years
Projects Completed During the Three Months Ended March 31, 2026
Millers Branch
Phase I
Solar200Haskell County, TXFebruary 202620 years
Wind Repowering Projects
During the three months ended March 31, 2026, Southern Power continued the development projects to repower the Kay, Grant, Grant Plains, Wake, and Bethel wind facilities. At March 31, 2026, the total cost of construction incurred related to the projects was $432 million, which is primarily included in CWIP. The repowered output of the facilities is contracted under new and amended PPAs. The ultimate outcome of these matters cannot be determined at this time.
Project FacilityResource
Approximate Nameplate
Capacity
(MW)
Location
Projected
Completion Date
Projects Under Construction at March 31, 2026
Kay(*)
Wind
200
Kay County, OK
Third quarter 2026
Grant
Wind
152
Grant County, OK
Fourth quarter 2026
Grant Plains
Wind
147
Grant County, OK
Fourth quarter 2026
Wake
Wind
257
Crosby & Floyd Counties, TX
Second quarter 2027
BethelWind276Castro County, TXThird quarter 2027
(*)The facility has a total capacity of 299 MWs, of which 200 MWs is projected to be repowered and is contracted under a PPA. During the first quarter 2026 and subsequent to March 31, 2026, Southern Power placed 51 MWs of repowered capacity in service.
Natural Gas Turbine Upgrade Projects
During the three months ended March 31, 2026, Southern Power committed to projects to upgrade certain turbines at its existing Franklin and Wansley natural gas facilities, located in Lee County, Alabama and Heard County, Georgia, respectively. The upgrades are projected to add up to 400 MWs of incremental capacity, with commercial operations projected to begin between the second quarter 2029 and the first quarter 2031. At March 31, 2026, the total cost of construction incurred related to the projects was immaterial. The ultimate outcome of these matters cannot be determined at this time.
v3.26.1
Segment and Related Information
 3 Months Ended
Mar. 31, 2026
Segment Reporting [Abstract]  
Segment and Related Information SEGMENT AND RELATED INFORMATION
See Note 16 to the financial statements in Item 8 of the Form 10-K for additional information.
Southern Company
The primary businesses of the Southern Company system are electricity sales by the traditional electric operating companies and Southern Power and the distribution of natural gas by Southern Company Gas. The traditional electric operating companies are vertically integrated utilities providing electric service in three Southeastern states. Southern Power develops, constructs, acquires, owns, operates, and manages power generation assets, including battery energy storage projects, and sells electricity at market-based rates in the wholesale market. Southern Company Gas distributes natural gas through its natural gas distribution utilities and is involved in several other complementary businesses including gas pipeline investments and gas marketing services.
Southern Company's reportable business segments are the sale of electricity by the traditional electric operating companies, the sale of electricity in the competitive wholesale market by Southern Power, and the distribution of natural gas and other complementary products and services by Southern Company Gas. While the traditional electric operating companies represent three separate operating segments, they are vertically integrated utilities providing electric service to retail customers, as well as wholesale customers, in the Southeast and have been aggregated into one reportable segment. The "All Other" presentation includes the Southern Company parent entity, which does not allocate operating expenses to business segments, and operating segments below the quantitative threshold for separate disclosure. These operating segments include providing distributed energy and resilience solutions and deploying microgrids for commercial, industrial, governmental, and utility customers, as well as investments in telecommunications. Revenues from sales by Southern Power to the traditional electric operating companies were $100 million and $116 million for the three months ended March 31, 2026 and 2025, respectively. All other inter-segment revenues were immaterial for both periods presented.
Southern Company's CODM utilizes segment net income, including variances to budget and forecasts, to assess performance and is not provided with segment expense information. To achieve the consolidated net income goal, Southern Company's CODM sets net income expectations for each operating segment, which is expected to monitor its expenses in order to achieve its assigned net income target. Therefore, Southern Company has no reportable significant segment expenses.
Financial data for business segments for the three months ended March 31, 2026 and 2025 was as follows:
Electric Utilities
Traditional
Electric Operating
Companies		Southern
Power		EliminationsTotalSouthern Company Gas
Total Reportable Segments
All
Other		EliminationsConsolidated
(in millions)
Three Months Ended March 31, 2026
Operating revenues$5,482 $681 $(141)$6,022 $2,191 $8,213 $218 $(34)$8,397 
Other segment items(a)
2,857 442 (141)3,158 1,357 4,515 190 (40)4,665 
Depreciation and amortization(b)
942 278 — 1,220 183 1,403 17 — 1,420 
Earnings from equity method investments(1)— — (1)46 45 5 — 50 
Interest expense(c)
339 27 — 366 105 471 307 — 778 
Income taxes (benefit)230 (70)— 160 145 305 (77)— 228 
Segment net income (loss)(b)(c)(d)
$1,113 $4 $— $1,117 $447 $1,564 $(214)$6 $1,356 
At March 31, 2026
Goodwill$— $2 $— $2 $5,015 $5,017 $144 $— $5,161 
Total assets115,965 12,474 (849)127,590 27,551 155,141 2,684 (794)157,031 
Three Months Ended March 31, 2025
Operating revenues$5,311 $567 $(123)$5,755 $1,839 $7,594 $229 $(48)$7,775 
Other segment items(a)
2,794 303 (123)2,974 1,069 4,043 208 (58)4,193 
Depreciation and amortization(b)
947 152 — 1,099 169 1,268 18 — 1,286 
Earnings from equity method investments(2)— — (2)39 37 (4)(1)32 
Interest expense316 26 — 342 92 434 280 — 714 
Income taxes (benefit)226 (1)— 225 130 355 (75)— 280 
Segment net income (loss)(b)(d)
$1,026 $87 $— $1,113 $418 $1,531 $(206)$9 $1,334 
At December 31, 2025
Goodwill$— $2 $— $2 $5,015 $5,017 $144 $— $5,161 
Total assets114,287 12,657 (915)126,029 27,387 153,416 2,829 (525)155,720 
(a)Primarily consists of fuel, purchased power, cost of natural gas, cost of other sales, other operations and maintenance, taxes other than income taxes, AFUDC equity, non-service cost-related retirement benefits income, and net income (loss) attributable to noncontrolling interests.
(b)For Southern Power, includes accelerated depreciation related to the repowering of multiple wind facilities of $154 million ($120 million after tax) and $27 million ($20 million after tax, net of noncontrolling interest impacts) for the three months ended March 31, 2026 and 2025, respectively. See Note (K) under "Southern Power – Wind Repowering Projects" and Notes 5 and 15 to the financial statements under "Depreciation and Amortization – Southern Power" and "Southern Power – Wind Repowering Projects," respectively, in Item 8 of the Form 10-K for additional information.
(c)For All Other, includes a pre-tax loss of $11 million ($8 million after tax) associated with the extinguishment of debt at the parent company.
(d)Attributable to Southern Company.
Traditional Electric Operating Companies
Each of the traditional electric operating companies' single reportable business segment is the sale of electricity.
Alabama Power and Georgia Power have identified utility operations and maintenance expenses as significant segment expenses provided to their CODMs. Utility operations and maintenance expenses is calculated as other operations and maintenance, as reflected on the statements of income, less expenses from unregulated products and services, losses (gains) on asset dispositions, impairment charges, and amortization of cloud software. Alabama Power's utility operations and maintenance expenses are disaggregated into expenses related to Rate RSE and Rate CNP Compliance. See Note 2 to the financial statements under "Alabama Power" in Item 8 of the Form 10-K for additional information.
During the third and fourth quarters of 2025, Mississippi Power updated the information provided to its CODM. As a result, Mississippi Power identified certain operational and environmental compliance expenses as significant segment expenses and has recast prior period information to conform to the current period presentation.
Financial data for significant segment expenses and other segment information for the three months ended March 31, 2026 and 2025 was as follows:
Three Months Ended March 31,
20262025
(in millions)
Alabama Power
Operating revenues$2,092 $2,012 
Utility operations and maintenance
Rate RSE expenses301 365 
Rate CNP Compliance expenses74 75 
Total utility operations and maintenance375 440 
Other segment items(a)
667 608 
Depreciation and amortization381 370 
Interest expense115 108 
Income taxes129 111 
Segment net income$425 $375 
Capital expenditures$519 $560 
Georgia Power
Operating revenues$3,142 $3,037 
Utility operations and maintenance578 536 
Other segment items(a)
1,163 1,117 
Depreciation and amortization484 503 
Interest expense204 187 
Income taxes85 98 
Segment net income$628 $596 
Capital expenditures$2,070 $1,637 
Three Months Ended March 31,
20262025
(in millions)
Mississippi Power
Operating revenues$472 $420 
Operational expenses(b)
64 57 
Environmental compliance expenses(c)
4 2 
Other segment items(a)
251 218 
Depreciation and amortization55 52 
Interest expense20 20 
Income taxes18 16 
Segment net income
$60 $55 
Capital expenditures$82 $73 
(a)Primarily consists of fuel, purchased power, expenses from unregulated products and services, losses (gains) on asset dispositions, amortization of cloud software, taxes other than income taxes, AFUDC equity, and non-service cost-related retirement benefits income. For Mississippi Power, includes employee benefit expenses. Also includes earnings from equity method investments, which were immaterial for all periods presented.
(b)Consists of certain operations and maintenance expenses related to PEP and the MRA tariff, including labor costs, materials, contract services, and other normal operational costs. See Note (B) under "Mississippi Power" and Note 2 to the financial statements under "Mississippi Power" in Item 8 of the Form 10-K for additional information regarding PEP and the MRA tariff.
(c)Consists of environmental compliance expenses related to ECO Plan and the MRA tariff. See Note (B) under "Mississippi Power" and Note 2 to the financial statements under "Mississippi Power" in Item 8 of the Form 10-K for additional information regarding ECO Plan and the MRA tariff.
Southern Power
Southern Power's single reportable business segment is the sale of electricity in the competitive wholesale market. Southern Power's CODM utilizes segment expense information in the form of variances to budget to assess performance; therefore, Southern Power has no reportable significant segment expenses.
Financial data for segment information for the three months ended March 31, 2026 and 2025 was as follows:
Three Months Ended March 31,
20262025
(in millions)
Operating revenues
$681 $567 
Other segment items(a)
442 303 
Depreciation and amortization(b)
278 152 
Interest expense27 26 
Income taxes (benefit)(70)(1)
Segment net income(b)(c)
$4 $87 
(a)Primarily consists of fuel, purchased power, other operations and maintenance, taxes other than income taxes, and net income (loss) attributable to noncontrolling interests.
(b)For the three months ended March 31, 2026 and 2025, includes accelerated depreciation of $154 million ($120 million after tax) and $27 million ($20 million after tax, net of noncontrolling interest impacts), respectively, related to the repowering of the multiple wind facilities. See Note (K) under "Southern Power – Wind Repowering Projects" and Notes 5 and 15 to the financial statements under "Depreciation and Amortization – Southern Power" and "Southern Power – Wind Repowering Projects," respectively, in Item 8 of the Form 10-K for additional information.
(c)Southern Power had no earnings from equity method investments for any period presented.
Southern Company Gas
Southern Company Gas manages its business through three reportable segments – gas distribution operations, gas pipeline investments, and gas marketing services. The non-reportable segments are combined and presented as "All Other."
The gas distribution operations segment is the largest component of Southern Company Gas' business and includes natural gas local distribution utilities that construct, manage, and maintain intrastate natural gas pipelines and gas distribution facilities in four states.
The gas pipeline investments segment consists of joint ventures in natural gas pipeline investments including a 50% interest in SNG and a 50% joint ownership interest in the Dalton Pipeline. These natural gas pipelines enable the provision of diverse sources of natural gas supplies to the customers of Southern Company Gas. See Note 7 to the financial statements under "Southern Company Gas" in Item 8 of the Form 10-K for additional information.
The gas marketing services segment provides natural gas marketing to end-use customers primarily in Georgia through SouthStar.
The "All Other" presentation includes operating segments and subsidiaries that fall below the quantitative threshold for separate disclosure.
Southern Company Gas' CODM utilizes segment expense information in the form of variances to budget to assess performance; therefore, Southern Company Gas has no reportable significant segment expenses.
Financial data for business segments for the three months ended March 31, 2026 and 2025 was as follows:
Gas Distribution OperationsGas
Pipeline Investments		Gas Marketing Services
Total Reportable Segments
All
Other
EliminationsConsolidated
(in millions)
Three Months Ended March 31, 2026
Operating revenues$1,900 $8 $285 $2,193 $2 $(4)$2,191 
Other segment items(*)
1,177 — 183 1,360 1 (4)1,357 
Depreciation and amortization179 1 2 182 1 — 183 
Earnings from equity method investments— 46 — 46 — — 46 
Interest expense91 9 1 101 4 — 105 
Income taxes (benefit)
116 11 28 155 (10)— 145 
Segment net income
$337 $33 $71 $441 $6 $— $447 
Total assets at March 31, 2026
$26,111 $1,517 $1,768 $29,396 $11,276 $(13,121)$27,551 
Three Months Ended March 31, 2025
Operating revenues$1,570 $8 $261 $1,839 $4 $(4)$1,839 
Other segment items(*)
905 1 166 1,072 1 (4)1,069 
Depreciation and amortization164 1 3 168 1 — 169 
Earnings from equity method investments— 39 — 39 — — 39 
Interest expense82 9 1 92 — — 92 
Income taxes (benefit)
104 9 26 139 (9)— 130 
Segment net income$315 $27 $65 $407 $11 $— $418 
Total assets at December 31, 2025
$25,391 $1,475 $1,749 $28,615 $10,643 $(11,871)$27,387 
(*)Primarily consists of cost of natural gas, other operations and maintenance, taxes other than income taxes, AFUDC equity, and non-service cost-related retirement benefits income.
v3.26.1
Insider Trading Arrangements
 3 Months Ended
Mar. 31, 2026
Trading Arrangements, by Individual  
Rule 10b5-1 Arrangement Adopted false
Non-Rule 10b5-1 Arrangement Adopted false
Rule 10b5-1 Arrangement Terminated false
Non-Rule 10b5-1 Arrangement Terminated false
v3.26.1
Introduction (Policies)
 3 Months Ended
Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Basis of Accounting
The condensed quarterly financial statements of each Registrant included herein have been prepared by such Registrant, without audit, pursuant to the rules and regulations of the SEC. The Condensed Balance Sheets at December 31, 2025 have been derived from the audited financial statements of each Registrant. In the opinion of each Registrant's management, the information regarding such Registrant furnished herein reflects all adjustments, which, except as otherwise disclosed, are of a normal recurring nature, necessary to present fairly the results of operations for the periods ended March 31, 2026 and 2025. Certain information and disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations, although each Registrant believes that the disclosures regarding such Registrant are adequate to make the information presented not misleading. Disclosures which would substantially duplicate the disclosures in the Form 10-K and details which have not changed significantly in amount or composition since the filing of the Form 10-K are generally omitted from this Quarterly Report on Form 10-Q unless specifically required by GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the financial statements and the notes thereto included in the Form 10-K. Due to the seasonal variations in the demand for energy and other factors, operating results for the periods presented are not necessarily indicative of the operating results to be expected for the full year.
Reclassifications
The preparation of financial statements in conformity with GAAP requires the use of estimates, and the actual results may differ from those estimates. Certain prior year data presented in the financial statements have been reclassified to conform to the current year presentation. These reclassifications had no impact on the overall results of operations, financial position, or cash flows of any Registrant.
Goodwill
Goodwill is not amortized but is subject to an annual impairment test during the fourth quarter of each year, or more frequently if goodwill impairment indicators exist.
Natural Gas for Sale
With the exception of Nicor Gas, Southern Company Gas records natural gas inventories on a weighted average cost basis. For any declines in market prices below the weighted average cost considered to be non-temporary, an adjustment is recorded to reduce the value of natural gas inventories to market value. Nicor Gas' natural gas inventory is carried at cost on a LIFO basis. Inventory decrements occurring during the year that are restored prior to year-end are charged to cost of natural gas at the estimated annual replacement cost. Inventory decrements that are not restored prior to year-end are charged to cost of natural gas at the actual LIFO cost of the inventory layers liquidated.
Valuation Methodologies
The energy-related derivatives primarily consist of exchange-traded and over-the-counter financial products for natural gas and physical power products, including, from time to time, basis swaps. These are standard products used within the energy industry and are valued using the market approach. The inputs used are mainly from observable market sources, such as forward natural gas prices, power prices, implied volatility, and overnight index swap interest rates. Interest rate derivatives are also standard over-the-counter products that are valued using observable market data and assumptions commonly used by market participants. The fair value of interest rate derivatives reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future interest rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and occasionally, implied volatility of interest rate options. The fair value of cross-currency swaps reflects the net present value of expected payments and receipts under the swap agreement based on the market's expectation of future foreign currency exchange rates. Additional inputs to the net present value calculation may include the contract terms, counterparty credit risk, and discount rates. The interest rate derivatives and cross-currency swaps are categorized as Level 2 under Fair Value Measurements as these inputs are based on observable data and valuations of similar instruments. See Note (J) for additional information on how these derivatives are used.
For fair value measurements of the investments within the nuclear decommissioning trusts and the non-qualified deferred compensation trusts, external pricing vendors are designated for each asset class with each security specifically assigned a primary pricing source. For investments held within commingled funds, fair value is determined at the end of each business day through the net asset value, which is established by obtaining the underlying securities' individual prices from the primary pricing source. A market price secured from the primary source vendor is then evaluated by management in its valuation of the assets within the trusts. As a general approach, fixed income market pricing vendors gather market data (including indices and market research reports) and integrate relative credit information, observed market movements, and sector news into proprietary pricing models, pricing systems, and mathematical tools. Dealer quotes and other market information, including live trading levels and pricing analysts' judgments, are also obtained when available.
The NRC requires licensees of commissioned nuclear power reactors to establish a plan for providing reasonable assurance of funds for future decommissioning. See Note 6 to the financial statements under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information.
Southern Company's investments, available for sale relate to a wholly-owned subsidiary that insures various risk exposures of Southern Company and its subsidiaries. Corporate and municipal bonds, government agency securities, and commercial paper are valued using pricing models maximizing the use of observable inputs for similar securities, including basing value on yields currently available on comparable securities of issues with similar credit ratings. Mortgage- and asset-backed securities are valued through an analysis of the underlying assets and a review of the documentation, including financials, the manager's valuation methodology in valuing their underlying assets, the types of assets and risks involved, and the investor's exit and termination parameters.
Southern Power has contingent payment obligations related to two of its acquisitions whereby it is primarily obligated to make generation-based payments to the seller, commencing at the commercial operation of each facility
and continuing through 2026 and 2036, respectively. The obligations are primarily categorized as Level 3 under Fair Value Measurements as the fair value is determined using significant unobservable inputs for the forecasted facility's generation in MW-hours, as well as other inputs such as a fixed dollar amount per MW-hour, and a discount rate. The fair value of the obligations reflects the net present value of expected payments and any periodic change arising from forecasted generation is expected to be immaterial.
Southern Power also has payment obligations through 2040 whereby it must reimburse the transmission owners for interconnection facilities and network upgrades constructed to support connection of a Southern Power generating facility to the transmission system. The obligations are categorized as Level 2 under Fair Value Measurements as the fair value is determined using observable inputs for the contracted amounts and reimbursement period, as well as a discount rate. The fair value of the obligations reflects the net present value of expected payments.
"Other investments" primarily includes investments traded in the open market that have maturities greater than 90 days, which are categorized as Level 2 under Fair Value Measurements and are comprised of corporate bonds, bank certificates of deposit, treasury bonds, and/or agency bonds.
Derivatives
The Registrants are exposed to market risks, including commodity price risk, interest rate risk, weather risk, and occasionally foreign currency exchange rate risk. To manage the volatility attributable to these exposures, each company nets its exposures, where possible, to take advantage of natural offsets and enters into various derivative transactions for the remaining exposures pursuant to each company's policies in areas such as counterparty exposure and risk management practices. Each company's policy is that derivatives are to be used primarily for hedging purposes and mandates strict adherence to all applicable risk management policies. Derivative positions are monitored using techniques including, but not limited to, market valuation, value at risk, stress testing, and sensitivity analysis. Derivative instruments are recognized at fair value in the balance sheets as either assets or liabilities and are presented on a net basis. See Note (I) for additional fair value information. In the statements of cash flows, any cash impacts of settled energy-related and interest rate derivatives are recorded as operating activities. Any cash impacts of settled foreign currency derivatives are classified as operating or financing activities to correspond with the classification of the hedged interest or principal, respectively. See Note 1 to the financial statements under "Financial Instruments" in Item 8 of the Form 10-K for additional information.
Energy-Related Derivatives
The Subsidiary Registrants enter into energy-related derivatives to hedge exposures to electricity, natural gas, and other fuel price changes. However, due to cost-based rate regulations and other various cost recovery mechanisms, the traditional electric operating companies and the natural gas distribution utilities have limited exposure to market volatility in energy-related commodity prices. Each of the traditional electric operating companies and certain of the natural gas distribution utilities manage fuel-hedging programs, implemented per the guidelines of their respective state PSCs or other applicable state regulatory agencies, through the use of financial derivative contracts, which are expected to continue to mitigate price volatility. The traditional electric operating companies (with respect to wholesale generating capacity) and Southern Power have limited exposure to market volatility in energy-related commodity prices because their long-term sales contracts shift substantially all fuel cost responsibility to the purchaser. However, the traditional electric operating companies and Southern Power may be exposed to market volatility in energy-related commodity prices to the extent any uncontracted capacity is used to sell electricity. Southern Company Gas retains exposure to price changes that can, in a volatile energy market, be material and can adversely affect its results of operations.
Southern Company Gas also enters into weather derivative contracts as economic hedges in the event of warmer-than-normal weather. Exchange-traded options are carried at fair value, with changes reflected in natural gas revenues. Non-exchange-traded options are accounted for using the intrinsic value method. Changes in the intrinsic value for non-exchange-traded contracts are reflected in natural gas revenues.
Energy-related derivative contracts are accounted for under one of three methods:
•Regulatory Hedges – Energy-related derivative contracts designated as regulatory hedges relate primarily to the traditional electric operating companies' and the natural gas distribution utilities' fuel-hedging programs, where gains and losses are initially recorded as regulatory liabilities and assets, respectively, and then are included in fuel expense as the underlying fuel is used in operations and ultimately recovered through an approved cost recovery mechanism.
•Cash Flow Hedges – Gains and losses on energy-related derivatives designated as cash flow hedges (which are mainly used to hedge anticipated purchases and sales) are initially deferred in accumulated OCI before being recognized in the statements of income in the same period and in the same income statement line item as the earnings effect of the hedged transactions.
•Not Designated – Gains and losses on energy-related derivative contracts that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred.
Some energy-related derivative contracts require physical delivery as opposed to financial settlement, and this type of derivative is both common and prevalent within the electric and natural gas industries. When an energy-related derivative contract is settled physically, any cumulative unrealized gain or loss is reversed and the contract price is recognized in the respective line item representing the actual price of the underlying goods being delivered.
Interest Rate Derivatives
Southern Company and certain subsidiaries may enter into interest rate derivatives to hedge exposure to changes in interest rates. Derivatives related to existing variable rate securities or forecasted transactions are accounted for as cash flow hedges where the derivatives' fair value gains or losses are recorded in OCI and are reclassified into earnings at the same time and presented on the same income statement line item as the earnings effect of the hedged transactions. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings on the same income statement line item. Fair value gains or losses on derivatives that are not designated or fail to qualify as hedges are recognized in the statements of income as incurred.
Foreign Currency Derivatives
Southern Company and certain subsidiaries, including Southern Power, may enter into foreign currency derivatives to hedge exposure to changes in foreign currency exchange rates, such as that arising from the issuance of debt denominated in a currency other than U.S. dollars. Derivatives related to forecasted transactions are accounted for as cash flow hedges where the derivatives' fair value gains or losses are recorded in OCI and are reclassified into earnings at the same time and on the same income statement line as the earnings effect of the hedged transactions, including foreign currency gains or losses arising from changes in the U.S. currency exchange rates. Derivatives related to existing fixed rate securities are accounted for as fair value hedges, where the derivatives' fair value gains or losses and hedged items' fair value gains or losses are both recorded directly to earnings on the same income statement line item, including foreign currency gains or losses arising from changes in the U.S. currency exchange rates. Southern Company has elected to exclude the cross-currency basis spread from the assessment of effectiveness in the fair value hedges of its foreign currency risk and record any difference between the change in the fair value of the excluded components and the amounts recognized in earnings as a component of OCI.
Derivative Financial Statement Presentation and Amounts
The Registrants enter into derivative contracts that may contain certain provisions that permit intra-contract netting of derivative receivables and payables for routine billing and offsets related to events of default and settlements. Southern Company and certain subsidiaries also utilize master netting agreements to mitigate exposure to counterparty credit risk. The fair value amounts of derivative assets and liabilities on the balance sheets are presented net to the extent that there are netting arrangements or similar agreements with the counterparties.
v3.26.1
Introduction (Tables)
 3 Months Ended
Mar. 31, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Goodwill
Goodwill at both March 31, 2026 and December 31, 2025 was as follows:
Goodwill
(in millions)
Southern Company$5,161 
Southern Company Gas:
Gas distribution operations$4,034 
Gas marketing services981 
Southern Company Gas total$5,015 
Schedule of Other Intangible Assets, Indefinite-Lived
Other intangible assets were as follows:
At March 31, 2026At December 31, 2025
Gross
Carrying
Amount		Accumulated
Amortization		Other
Intangible
Assets,
Net		Gross
Carrying
Amount		Accumulated
Amortization		Other
Intangible
Assets,
Net
(in millions)(in millions)
Southern Company
Subject to amortization:
Customer relationships$212 $(190)$22 $212 $(189)$23 
Trade names64 (64)— 64 (64)— 
PPA fair value adjustments390 (193)197 390 (188)202 
Other3 (3)— 3 (3)— 
Total subject to amortization$669 $(450)$219 $669 $(444)$225 
Not subject to amortization:
FCC licenses75 — 75 75 — 75 
Total other intangible assets$744 $(450)$294 $744 $(444)$300 
Southern Power(*)
PPA fair value adjustments$390 $(193)$197 $390 $(188)$202 
Southern Company Gas(*)
Gas marketing services
Customer relationships$156 $(154)$2 $156 $(153)$3 
Trade names26 (26)— 26 (26)— 
Total other intangible assets$182 $(180)$2 $182 $(179)$3 
(*)All subject to amortization.
Schedule of Other Intangible Assets, Finite-Lived
Other intangible assets were as follows:
At March 31, 2026At December 31, 2025
Gross
Carrying
Amount		Accumulated
Amortization		Other
Intangible
Assets,
Net		Gross
Carrying
Amount		Accumulated
Amortization		Other
Intangible
Assets,
Net
(in millions)(in millions)
Southern Company
Subject to amortization:
Customer relationships$212 $(190)$22 $212 $(189)$23 
Trade names64 (64)— 64 (64)— 
PPA fair value adjustments390 (193)197 390 (188)202 
Other3 (3)— 3 (3)— 
Total subject to amortization$669 $(450)$219 $669 $(444)$225 
Not subject to amortization:
FCC licenses75 — 75 75 — 75 
Total other intangible assets$744 $(450)$294 $744 $(444)$300 
Southern Power(*)
PPA fair value adjustments$390 $(193)$197 $390 $(188)$202 
Southern Company Gas(*)
Gas marketing services
Customer relationships$156 $(154)$2 $156 $(153)$3 
Trade names26 (26)— 26 (26)— 
Total other intangible assets$182 $(180)$2 $182 $(179)$3 
(*)All subject to amortization.
Schedule of Amortization of Other Intangible Assets
Amortization associated with other intangible assets was as follows:
Three Months Ended March 31,
20262025
(in millions)
Southern Company(a)
$7 $8 
Southern Power(b)
5 5 
Southern Company Gas
Gas marketing services1 2 
(a)Includes $5 million for the three months ended March 31, 2026 and 2025 recorded as a reduction to operating revenues.
(b)Recorded as a reduction to operating revenues.
Schedule of Restrictions on Cash and Cash Equivalents
The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that total to the amount shown in the condensed statements of cash flows for the applicable Registrants:
Southern CompanySouthern
Company Gas
(in millions)
At March 31, 2026
Cash and cash equivalents$981 $137 
Restricted cash(*):
Other current assets
6 5 
Total cash, cash equivalents, and restricted cash
$987 $142 
At December 31, 2025
Cash and cash equivalents$1,639 $15 
Restricted cash(*):
Other current assets
1 — 
Total cash, cash equivalents, and restricted cash
$1,640 $15 
(*)For Southern Company Gas, reflects funds held to support letters of credit. For Southern Company, also reflects collateral of $1 million for life insurance and long-term disability insurance, which was included at Southern Holdings.
Schedule of Cash and Cash Equivalents
The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that total to the amount shown in the condensed statements of cash flows for the applicable Registrants:
Southern CompanySouthern
Company Gas
(in millions)
At March 31, 2026
Cash and cash equivalents$981 $137 
Restricted cash(*):
Other current assets
6 5 
Total cash, cash equivalents, and restricted cash
$987 $142 
At December 31, 2025
Cash and cash equivalents$1,639 $15 
Restricted cash(*):
Other current assets
1 — 
Total cash, cash equivalents, and restricted cash
$1,640 $15 
(*)For Southern Company Gas, reflects funds held to support letters of credit. For Southern Company, also reflects collateral of $1 million for life insurance and long-term disability insurance, which was included at Southern Holdings.
v3.26.1
Regulatory Matters (Tables)
 3 Months Ended
Mar. 31, 2026
Regulated Operations [Abstract]  
Schedule of Cost Recovery Clauses
The recovery balances for retail fuel and storm/property damage for the traditional electric operating companies and natural gas cost for Southern Company Gas at March 31, 2026 and December 31, 2025 were as follows:
Recovery/Regulatory ClauseBalance Sheet LocationAt March 31, 2026At December 31, 2025
(in millions)
Alabama Power
Rate ECROther regulatory assets, deferred$200 $146 
NDROther regulatory liabilities, deferred52 60 
Georgia Power
Fuel cost recovery
Receivables – under recovered retail fuel clause revenues
$234 $310 
Deferred under recovered retail fuel clause revenues210 212 
Storm damage recoveryOther regulatory assets, current31 31 
Other regulatory assets, deferred962 880 
Mississippi Power
Fuel cost recovery(*)
Receivables – customer accounts, net$55 $— 
Deferred under recovered retail fuel clause revenues— 40 
Property damage reserveOther regulatory liabilities, deferred57 57 
Southern Company Gas
Natural gas cost recoveryNatural gas cost over recovery$131 $158 
(*)Mississippi Power also has wholesale MRA and Market Based (MB) fuel cost recovery factors. At March 31, 2026 and December 31, 2025, wholesale MRA fuel cost under recovery was $9 million and $6 million, respectively, and was included in customer accounts receivable, net on Mississippi Power's balance sheets. The wholesale MB fuel cost recovery was immaterial for both periods presented.
Schedule of Construction Projects
Resource/Project
Approximate Nameplate Capacity
(MW)
Actual/Projected COD
Projects Under Construction at March 31, 2026
Battery Energy Storage
McGrau Ford Phase 1265Fourth quarter 2026
Twiggs County200Fourth quarter 2027
Wadley260Fourth quarter 2027
Bowen Phase 1
250Fourth quarter 2028
Bowen Phase 2
250Fourth quarter 2029
South Hall250Fourth quarter 2028
Wansley
500Fourth quarter 2028
Yates Phase 1
320Fourth quarter 2028
Yates Phase 2
250Fourth quarter 2028
Thomson500Fourth quarter 2029
Hammond Phase 2193Fourth quarter 2030
McIntosh
250Fourth quarter 2030
Various facilities(a)
372Second quarter 2026 through
fourth quarter 2026
Solar with Battery Energy Storage
Laurens County 200Fourth quarter 2028
Plant Mitchell 150Fourth quarter 2028
Combined Cycle
Plant Bowen Unit 7741Fourth quarter 2029
Plant Bowen Unit 8741Second quarter 2030
Plant McIntosh Unit 12757Fourth quarter 2030
Plant Wansley Unit 10727Fourth quarter 2029
Plant Wansley Unit 11727Second quarter 2030
Combustion Turbine
Plant Yates Unit 8(b)
442Fourth quarter 2026
Plant Yates Unit 9(b)
442Second quarter 2027
Plant Yates Unit 10(b)
442Third quarter 2027
Projects Completed During the Three Months Ended March 31, 2026
Battery Energy Storage
Robins
128March 2026
(a)Subsequent to March 31, 2026, Georgia Power completed construction of the 50-MW Moody battery energy storage facility.
(b)Pursuant to the 2023 IRP Update, cost recovery over the certified amount is limited.
v3.26.1
Revenue from Contracts with Customers and Lease Income (Tables)
 3 Months Ended
Mar. 31, 2026
Revenue from Contract with Customer [Abstract]  
Schedule of Disaggregation of Revenue
The following table disaggregates revenue from contracts with customers for the three months ended March 31, 2026 and 2025:
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Three Months Ended March 31, 2026
Operating revenues
Retail electric revenues
Residential$2,003 $773 $1,150 $80 $— $— 
Commercial1,663 477 1,104 82 — — 
Industrial942 414 438 90 — — 
Other31 3 25 3 — — 
Total retail electric revenues4,639 1,667 2,717 255 — — 
Natural gas distribution revenues
Residential1,028 — — — — 1,028 
Commercial253 — — — — 253 
Transportation440 — — — — 440 
Industrial 24 — — — — 24 
Other145 — — — — 145 
Total natural gas distribution revenues1,890 — — — — 1,890 
Wholesale electric revenues
PPA energy revenues496 46 64 4 392 — 
PPA capacity revenues149 18 44 21 83 — 
Non-PPA revenues89 119 44 169 44 — 
Total wholesale electric revenues734 183 152 194 519 — 
Other natural gas revenues
Gas marketing services281 — — — — 281 
Other
3 — — — — 3 
Total other natural gas revenues
284 — — — — 284 
Other revenues493 78 236 15 4 — 
Total revenue from contracts with customers8,040 1,928 3,105 464 523 2,174 
Other revenue sources(*)
357 164 37 8 158 17 
Total operating revenues$8,397 $2,092 $3,142 $472 $681 $2,191 
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Three Months Ended March 31, 2025
Operating revenues
Retail electric revenues
Residential$2,065 $805 $1,186 $74 $— $— 
Commercial1,612 482 1,055 75 — — 
Industrial915 390 444 81 — — 
Other31 3 26 2 — — 
Total retail electric revenues4,623 1,680 2,711 232 — — 
Natural gas distribution revenues
Residential845 — — — — 845 
Commercial199 — — — — 199 
Transportation406 — — — — 406 
Industrial 18 — — — — 18 
Other112 — — — — 112 
Total natural gas distribution revenues1,580 — — — — 1,580 
Wholesale electric revenues
PPA energy revenues415 54 84 3 284 — 
PPA capacity revenues149 28 39 17 82 — 
Non-PPA revenues71 69 9 134 62 — 
Total wholesale electric revenues635 151 132 154 428 — 
Other natural gas revenues
Gas marketing services256 — — — — 256 
Other
4 — — — — 4 
Total other natural gas revenues
260 — — — — 260 
Other revenues493 83 230 20 4 — 
Total revenue from contracts with customers7,591 1,914 3,073 406 432 1,840 
Other revenue sources(*)
184 98 (36)14 135 (1)
Total operating revenues$7,775 $2,012 $3,037 $420 $567 $1,839 
(*)Other revenue sources relate to revenues from customers accounted for as derivatives and leases, alternative revenue programs primarily at Southern Company Gas, and cost recovery mechanisms and revenues (including those related to fuel costs) that meet other scope exceptions for revenues from contracts with customers at the traditional electric operating companies.
Schedule of Contract Balances
The following table reflects the closing balances of receivables, contract assets, and contract liabilities related to revenues from contracts with customers at March 31, 2026 and December 31, 2025:
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Accounts Receivable
At March 31, 2026$3,083 $649 $1,179 $119 $94 $925 
At December 31, 20253,139 716 1,278 115 132 864 
Contract Assets
At March 31, 2026$338 $5 $196 $— $— $67 
At December 31, 2025294 3 160 — — 67 
Contract Liabilities
At March 31, 2026$257 $9 $76 $2 $1 $— 
At December 31, 2025213 6 75 — 2 — 
Schedule of Remaining Performance Obligations Revenues from contracts with customers related to these performance obligations remaining at March 31, 2026 are expected to be recognized as follows:
2026 (remaining)2027202820292030Thereafter
(in millions)
Southern Company$875 $679 $452 $412 $416 $3,130 
Alabama Power8 5 4 2 1 6 
Georgia Power48 60 43 22 22 146 
Mississippi Power(*)
49 69 73 12 — — 
Southern Power(*)
270 349 389 393 393 2,978 
Southern Company Gas31 21 — — — — 
(*)Includes performance obligations related to affiliate PPAs with Georgia Power. See Note 1 to the financial statements under "Affiliate Transactions" in Item 8 of the Form 10-K for additional information.
Schedule of Lease Income
Lease income for the three months ended March 31, 2026 and 2025 was as follows:
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
 (in millions)
Three Months Ended March 31, 2026
Lease income - interest income on sales-type leases$5 $— $— $3 $2 $— 
Lease income - operating leases34 3 7 1 37 9 
Variable lease income79 — — — 87 — 
Total lease income$118 $3 $7 $4 $126 $9 
Three Months Ended March 31, 2025
Lease income - interest income on sales-type leases$6 $— $— $4 $2 $— 
Lease income - operating leases33 2 7 1 37 9 
Variable lease income81 — — — 89 — 
Total lease income$120 $2 $7 $5 $128 $9 
v3.26.1
Consolidated Entities and Equity Method Investments (Tables)
 3 Months Ended
Mar. 31, 2026
Regulated Operations [Abstract]  
Schedule of Equity Method Investments
The carrying amounts of Southern Company Gas' equity method investments at March 31, 2026 and December 31, 2025 were as follows:
Investment BalanceAt March 31, 2026At December 31, 2025
(in millions)
SNG$1,190 $1,148 
Other34 34 
Total$1,224 $1,182 
v3.26.1
Financing (Tables)
 3 Months Ended
Mar. 31, 2026
Debt Disclosure [Abstract]  
Schedule of Credit Arrangements
At March 31, 2026, committed credit arrangements with banks were as follows:
Expires
Company20262028202920302031TotalUnusedExpires 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 15 
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 — 
SEGCO30 — — — — 30 30 30 
Southern Company$45 $500 $775 $2,300 $5,300 $8,920 $8,909 $45 
(a)Arrangement expiring in 2031 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, Mississippi Power, and Southern 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 March 31, 2026. 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 March 31, 2026.
(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 March 31, 2026. In addition, Southern Power Company had $23 million of letters of credit outstanding under an uncommitted letter of credit facility at March 31, 2026. 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 and settled under separate forward sale contracts with forward purchasers during the three months ended March 31, 2026.
Shares Sold
Initial Forward Price per Share
To be Settled On or Before
Forward Price Per Share SettledShares Issued to SettleSettlement Date
Sold during 2025
3,255,866$89.4692December 31, 2026$89.24433,255,866March 2, 2026
2,314,487$92.7805June 30, 2027$92.87232,314,487March 2, 2026
Sold during 2026
1,467,305$96.3883March 31, 2028N/AN/AN/A
1,896,549$97.5815March 31, 2028N/AN/AN/A
1,903,317$95.5086March 31, 2028N/AN/AN/A
Schedule of Shares Used to Compute Diluted Earnings Per Share Shares used to compute diluted EPS were as follows:
Three Months Ended March 31,
20262025

(in millions)
As reported shares1,124 1,100 
Effect of stock-based compensation4 5 
Diluted shares1,128 1,105 
v3.26.1
Retirement Benefits (Tables)
 3 Months Ended
Mar. 31, 2026
Retirement Benefits [Abstract]  
Schedule of Pension Plans and Postretirement Plans Components of the net periodic benefit costs for the three months ended March 31, 2026 and 2025 are presented in the following tables.
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Three Months Ended March 31, 2026
Pension Plans
Service cost$69 $15 $17 $3 $2 $7 
Interest cost162 38 47 7 2 11 
Expected return on plan assets(322)(79)(99)(15)(4)(21)
Amortization:
Prior service costs— — — — — (1)
Regulatory asset— — — — — 3 
Net loss18 5 6 1 — — 
Net periodic pension income$(73)$(21)$(29)$(4)$— $(1)
Postretirement Benefits
Service cost$3 $1 $1 $— $— $— 
Interest cost16 4 6 1 — 2 
Expected return on plan assets(23)(9)(8)(1)— (2)
Amortization:
Prior service costs1 — — — — — 
Net gain(2)— — — — (2)
Net periodic postretirement benefit income$(5)$(4)$(1)$— $— $(2)
Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power		Southern
Company
Gas
(in millions)
Three Months Ended March 31, 2025
Pension Plans
Service cost$66 $15 $16 $3 $1 $7 
Interest cost166 39 49 7 2 11 
Expected return on plan assets(320)(78)(99)(15)(4)(22)
Amortization:
Prior service costs— — — — — (1)
Regulatory asset— — — — — 4 
Net loss9 2 4 1 1 — 
Net periodic pension income$(79)$(22)$(30)$(4)$— $(1)
Postretirement Benefits
Service cost$3 $1 $1 $— $— $— 
Interest cost17 4 6 1 — 2 
Expected return on plan assets(23)(9)(8)— — (2)
Amortization:
Prior service costs1 — — — — — 
Regulatory asset— — — — — 2 
Net gain(3)— — (1)— (2)
Net periodic postretirement benefit income$(5)$(4)$(1)$— $— $— 
v3.26.1
Fair Value Measurements (Tables)
 3 Months Ended
Mar. 31, 2026
Fair Value Disclosures [Abstract]  
Schedule of Assets and Liabilities Measured at Fair Value
At March 31, 2026, assets and liabilities measured at fair value on a recurring basis during the period, together with their associated level of the fair value hierarchy, were as follows:
Fair Value Measurements Using
At March 31, 2026Quoted Prices
in Active
Markets for
Identical
Assets
(Level 1)		Significant
Other
Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)		Net Asset
Value as a
Practical
Expedient
(NAV)		Total
(in millions)
Southern Company
Assets:
Energy-related derivatives(a)
$2 $76 $— $— $78 
Interest rate derivatives— 7 — — 7 
Foreign currency derivatives— 5 — — 5 
Investments in trusts:(b)
Domestic equity884 259 — — 1,143 
Foreign equity177 231 — — 408 
U.S. Treasury and government agency securities— 390 — — 390 
Municipal bonds— 50 — — 50 
Pooled funds – fixed income— 4 — — 4 
Corporate bonds— 529 — — 529 
Mortgage- and asset-backed securities — 108 — — 108 
Private equity— — — 195 195 
Cash and cash equivalents1 — — — 1 
Other63 3 — 9 75 
Investments, available-for-sale:
U.S. Treasury and government agency securities2 12 — — 14 
Municipal bonds— 1 — — 1 
Corporate bonds— 3 — — 3 
Mortgage- and asset-backed securities— 4 — — 4 
Cash equivalents486 15 — — 501 
Other investments10 39 8 — 57 
Other— — 10 — 10 
Total$1,625 $1,736 $18 $204 $3,583 
Liabilities:
Energy-related derivatives(a)
$9 $151 $— $— $160 
Interest rate derivatives— 191 — — 191 
Foreign currency derivatives— 50 — — 50 
Contingent consideration— — 11 — 11 
Other— 13 11 — 24 
Total$9 $405 $22 $— $436 
Fair Value Measurements Using
At March 31, 2026Quoted Prices
in Active
Markets for
Identical
Assets
(Level 1)		Significant
Other
Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)		Net Asset
Value as a
Practical
Expedient
(NAV)		Total
(in millions)
Alabama Power
Assets:
Energy-related derivatives$— $25 $— $— $25 
Nuclear decommissioning trusts:(b)
Domestic equity502 248 — — 750 
Foreign equity177 — — — 177 
U.S. Treasury and government agency securities— 15 — — 15 
Municipal bonds— 1 — — 1 
Corporate bonds— 317 — — 317 
Mortgage- and asset-backed securities— 30 — — 30 
Private equity— — — 195 195 
Other13 1 — 9 23 
Cash equivalents9 15 — — 24 
Other investments— 39 — — 39 
Total$701 $691 $— $204 $1,596 
Liabilities:
Energy-related derivatives$— $48 $— $— $48 
Georgia Power
Assets:
Energy-related derivatives$— $25 $— $— $25 
Nuclear decommissioning trusts:(b)
Domestic equity382 1 — — 383 
Foreign equity— 229 — — 229 
U.S. Treasury and government agency securities— 375 — — 375 
Municipal bonds— 49 — — 49 
Corporate bonds— 212 — — 212 
Mortgage- and asset-backed securities— 78 — — 78 
Other50 2 — — 52 
Cash equivalents8 — — — 8 
Total$440 $971 $— $— $1,411 
Liabilities:
Energy-related derivatives$— $49 $— $— $49 
Mississippi Power
Assets:
Energy-related derivatives$— $19 $— $— $19 
Liabilities:
Energy-related derivatives$— $38 $— $— $38 
Fair Value Measurements Using
At March 31, 2026Quoted Prices
in Active
Markets for
Identical
Assets
(Level 1)		Significant
Other
Observable
Inputs
(Level 2)		Significant
Unobservable
Inputs
(Level 3)		Net Asset
Value as a
Practical
Expedient
(NAV)		Total
(in millions)
Southern Power
Assets:
Energy-related derivatives$— $4 $— $— $4 
Foreign currency derivatives— 5 — — 5 
Other— — 10 — 10 
Total$— $9 $10 $— $19 
Liabilities:
Energy-related derivatives$— $3 $— $— $3 
Contingent consideration— — 11 — 11 
Other— 13 11 — 24 
Total$— $16 $22 $— $38 
Southern Company Gas
Assets:
Energy-related derivatives(a)
$2 $3 $— $— $5 
Non-qualified deferred compensation trusts:
Domestic equity— 10 — — 10 
Foreign equity— 2 — — 2 
Pooled funds – fixed income— 4 — — 4 
Cash and cash equivalents1 — — — 1 
Cash equivalents121 — — — 121 
Total$124 $19 $— $— $143 
Liabilities:
Energy-related derivatives(a)
$9 $13 $— $— $22 
Interest rate derivatives— 55 — — 55 
Total$9 $68 $— $— $77 
(a)Excludes cash collateral of $22 million.
(b)Excludes receivables related to investment income, pending investment sales, payables related to pending investment purchases, and currencies. See Note 6 to the financial statements under "Nuclear Decommissioning" in Item 8 of the Form 10-K for additional information.
Schedule of Increase (Decrease) In Fair Value Of Funds The changes were recorded as a change to the regulatory assets and liabilities related to AROs for Georgia Power and Alabama Power, respectively.
Three Months Ended March 31,
Fair value increases (decreases)20262025
(in millions)
Southern Company $(44)$(6)
Alabama Power (30)(13)
Georgia Power(14)7 
Schedule of Financial Instruments for which Carrying Amount Did Not Equal Fair Value
At March 31, 2026, other financial instruments for which the carrying amount did not equal fair value were as follows:
Southern
   Company(*)
Alabama
Power		Georgia
Power		Mississippi
Power		Southern
Power
Southern
Company
   Gas(*)
(in billions)
Long-term debt, including securities due within one year:
Carrying amount$72.1 $12.0 $21.7 $1.8 $2.9 $9.3 
Fair value66.5 10.7 20.2 1.7 2.8 8.3 
(*)The carrying amount of Southern Company Gas' long-term debt includes fair value adjustments from the effective date of the 2016 merger with Southern Company. Southern Company Gas amortizes the fair value adjustments over the remaining lives of the respective bonds, the latest being through 2043.
v3.26.1
Derivatives (Tables)
 3 Months Ended
Mar. 31, 2026
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Schedule of Energy-Related Derivatives
At March 31, 2026, the net volume of energy-related derivative contracts for natural gas positions, together with the longest hedge date over which the respective entity is hedging its exposure to the variability in future cash flows for forecasted transactions and the longest non-hedge date for derivatives not designated as hedges, were as follows:
Net
Purchased
mmBtu		Longest
Hedge
Date		Longest
Non-Hedge
Date
(in millions)
Southern Company(*)
46920302029
Alabama Power14520292026
Georgia Power13220282026
Mississippi Power11220302026
Southern Power720302026
Southern Company Gas(*)
7320282029
(*)Southern Company Gas' derivative instruments include both long and short natural gas positions. A long position is a contract to purchase natural gas and a short position is a contract to sell natural gas. Southern Company Gas' volume represents the net of 80 million mmBtu long natural gas positions and 7 million mmBtu short natural gas positions at March 31, 2026, which is also included in Southern Company's total volume.
Schedule of Interest Rate Derivatives
At March 31, 2026, the following interest rate derivatives were outstanding:
Notional
Amount		Weighted
Average Interest
Rate Paid		Interest
Rate
Received		Hedge
Maturity
Date
Fair Value
Gain (Loss) at
March 31, 2026
 (in millions)   (in millions)
Fair Value Hedges of Existing Debt
Southern Company parent$400 
1-day SOFR + 0.80%
1.75%March 2028$(20)
Southern Company parent1,000 
1-day SOFR + 2.48%
3.70%April 2030(103)
Southern Company parent565 
1-day SOFR + 1.56%
6.50%March 2045(6)
Southern Company Gas500 
1-day SOFR + 0.49%
1.75%January 2031(55)
Southern Company$2,465 $(184)
Schedule of Foreign Currency Derivatives
At March 31, 2026, the following foreign currency derivatives were outstanding:
Pay
Notional		Pay
Rate		Receive
Notional		Receive
Rate		Hedge
Maturity Date
Fair Value
Gain (Loss) at
March 31, 2026
(in millions)(in millions)(in millions)
Cash Flow Hedges of Existing Debt
Southern Power$564 3.78%€500 1.85%June 2026$5 
Fair Value Hedges of Existing Debt
Southern Company parent1,476 3.39%1,250 1.88%September 2027(50)
Southern Company$2,040 €1,750 $(45)
Schedule of Derivative Category and Balance Sheet Location
The fair value of energy-related derivatives, interest rate derivatives, and foreign currency derivatives was reflected as either assets or liabilities in the balance sheets (included in "Other" or shown separately as "Risk Management Activities") as follows:
At March 31, 2026At December 31, 2025
Derivative Category and Balance Sheet LocationAssetsLiabilitiesAssetsLiabilities
(in millions)
Southern Company
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current
$35 $91 $24 $64 
Non-current
34 56 31 35 
Total derivatives designated as hedging instruments for regulatory purposes69 147 55 99 
Derivatives designated as hedging instruments in cash flow and fair value hedges
Energy-related derivatives:
Current2 8 1 6 
Non-current2 — 2 1 
Interest rate derivatives:
Current7 49 8 48 
Non-current— 142 — 139 
Foreign currency derivatives:
Current5 22 17 22 
Non-current— 28 4 — 
Total derivatives designated as hedging instruments in cash flow and fair value hedges16 249 32 216 
Energy-related derivatives not designated as hedging instruments
Current5 5 6 6 
Gross amounts recognized90 401 93 321 
Gross amounts offset(a)
(53)(75)(21)(54)
Net amounts recognized in the Balance Sheets(b)
$37 $326 $72 $267 
Alabama Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current$12 $26 $9 $18 
Non-current13 22 10 13 
Total derivatives designated as hedging instruments for regulatory purposes25 48 19 31 
Gross amounts offset(23)(23)(13)(13)
Net amounts recognized in the Balance Sheets$2 $25 $6 $18 
At March 31, 2026At December 31, 2025
Derivative Category and Balance Sheet LocationAssetsLiabilitiesAssetsLiabilities
(in millions)
Georgia Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current$13 $32 $7 $23 
Non-current9 17 10 10 
Total derivatives designated as hedging instruments for regulatory purposes22 49 17 33 
Energy-related derivatives not designated as hedging instruments
Current
3 — 1 — 
Gross amounts recognized25 49 18 33 
Gross amounts offset(21)(21)(14)(14)
Net amounts recognized in the Balance Sheets$4 $28 $4 $19 
Mississippi Power
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current$7 $21 $3 $15 
Non-current12 17 11 12 
Total derivatives designated as hedging instruments for regulatory purposes19 38 14 27 
Gross amounts offset(18)(18)(13)(13)
Net amounts recognized in the Balance Sheets$1 $20 $1 $14 
Southern Power
Derivatives designated as hedging instruments in cash flow hedges
Energy-related derivatives:
Current$1 $2 $1 $1 
Non-current2 — 2 — 
Foreign currency derivatives:
Current5 — 17 — 
Total derivatives designated as hedging instruments in cash flow hedges
8 2 20 1 
Energy-related derivatives not designated as hedging instruments
Energy-related derivatives:
Current
1 1 1 — 
Gross amounts recognized9 3 21 1 
Gross amounts offset(1)(1)— — 
Net amounts recognized in the Balance Sheets$8 $2 $21 $1 
At March 31, 2026At December 31, 2025
Derivative Category and Balance Sheet LocationAssetsLiabilitiesAssetsLiabilities
(in millions)
Southern Company Gas
Energy-related derivatives designated as hedging instruments for regulatory purposes
Current
$3 $12 $5 $8 
Derivatives designated as hedging instruments in cash flow and fair value hedges
Energy-related derivatives:
Current1 6 — 5 
Non-current— — — 1 
Interest rate derivatives:
Current— 12 — 13 
Non-current— 43 — 46 
Total derivatives designated as hedging instruments in cash flow and fair value hedges1 61 — 65 
Energy-related derivatives not designated as hedging instruments
Current1 4 4 6 
Gross amounts recognized5 77 9 79 
Gross amounts offset(a)
10 (12)19 (14)
Net amounts recognized in the Balance Sheets(b)
$15 $65 $28 $65 
(a)Gross amounts offset includes cash collateral held on deposit in broker margin accounts of $22 million and $33 million at March 31, 2026 and December 31, 2025, respectively.
(b)Net amounts of derivative instruments outstanding exclude immaterial premium and intrinsic value associated with weather derivatives at March 31, 2026 and December 31, 2025.
Schedule of Pre-tax Effects of Unrealized Derivative Gains (Losses)
At March 31, 2026 and December 31, 2025, the pre-tax effects of unrealized derivative gains (losses) arising from energy-related derivative instruments designated as regulatory hedging instruments and deferred were as follows:
Regulatory Hedge Unrealized Gain (Loss) Recognized in the Balance Sheets
Derivative Category and Balance Sheet
Location		Southern
Company		Alabama
Power		Georgia
Power		Mississippi
Power		Southern Company Gas
 (in millions)
At March 31, 2026:
Energy-related derivatives:
Other regulatory assets, current$(60)$(16)$(20)$(14)$(10)
Other regulatory assets, deferred(23)(10)(8)(5)— 
Other regulatory liabilities, current4 2 1 — 1 
Other regulatory liabilities, deferred1 1 — — — 
Total energy-related derivative gains (losses)$(78)$(23)$(27)$(19)$(9)
At December 31, 2025:
Energy-related derivatives:
Other regulatory assets, current$(48)$(13)$(17)$(12)$(6)
Other regulatory assets, deferred(8)(5)(1)(2)— 
Other regulatory liabilities, current7 4 1 — 2 
Other regulatory liabilities, deferred4 2 1 1 — 
Total energy-related derivative gains (losses)$(45)$(12)$(16)$(13)$(4)
Schedule of Pre-Tax Effects of Hedging on AOCI
For the three months ended March 31, 2026 and 2025, the pre-tax effects of cash flow and fair value hedge accounting on accumulated OCI for the applicable Registrants were as follows:
Gain (Loss) From Derivatives Recognized in OCIThree Months Ended March 31,
20262025
(in millions)
Southern Company
Cash flow hedges:
Energy-related derivatives$10 $19 
Interest rate derivatives— (2)
Foreign currency derivatives(12)19 
Fair value hedges(*):
Foreign currency derivatives(1)(16)
Total$(3)$20 
Georgia Power
Cash flow hedges:
Interest rate derivatives$— $(2)
Southern Power
Cash flow hedges:
Energy-related derivatives$2 $3 
Foreign currency derivatives(12)19 
Total$(10)$22 
Southern Company Gas
Cash flow hedges:
Energy-related derivatives$8 $16 
(*)Represents amounts excluded from the assessment of effectiveness for which the difference between changes in fair value and periodic amortization is recorded in OCI.
Schedule of Pre-Tax Effects of Cash Flow and Fair Value Hedging on Income
For the three months ended March 31, 2026 and 2025, the pre-tax effects of cash flow and fair value hedge accounting on income were as follows:
Gain (Loss)
Statements of Income Location
Derivative Category
Three Months Ended March 31,
20262025
(in millions)
Southern Company
Fuel
Energy-related cash flow hedges
$3 $1 
Cost of natural gas
Energy-related cash flow hedges
10 (1)
Interest expense, net of amounts capitalized
Interest rate cash flow hedges
(2)(2)
Foreign currency cash flow hedges
(3)(3)
Interest rate fair value hedges
20 40 
Other income (expense), net
Foreign currency cash flow hedges
(13)21 
Foreign currency fair value hedges
(32)40 
Amount excluded from effectiveness testing recognized in earnings1 16 
Southern Power
Fuel
Energy-related cash flow hedges
$3 $1 
Interest expense, net of amounts capitalized
Foreign currency cash flow hedges
(3)(3)
Other income (expense), net
Foreign currency cash flow hedges
(13)21 
Southern Company Gas
Cost of natural gas
Energy-related cash flow hedges
$10 $(1)
Interest expense, net of amounts capitalized
Interest rate fair value hedges
29 17 
Schedule of Cumulative Basis Adjustments for Fair Value Hedges
At March 31, 2026 and December 31, 2025, the following amounts were recorded on the balance sheets related to cumulative basis adjustments for fair value hedges:
Carrying Amount of the Hedged
Item		Cumulative Amount of Fair Value
Hedging Adjustment included in
Carrying Amount of the Hedged
Item
Balance Sheet Location of Hedged ItemsAt March 31, 2026At December 31, 2025At March 31, 2026At December 31, 2025
(in millions)
Southern Company
Long-term debt$(3,710)$(3,742)$158 $156 
Southern Company Gas
Long-term debt$(446)$(446)$52 $51 
v3.26.1
Acquisitions and Dispositions (Tables)
 3 Months Ended
Mar. 31, 2026
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]  
Schedule of Asset Acquisitions
Project
Facility		Resource
Approximate
Nameplate Capacity
(MW)
LocationActual/Projected
COD		PPA
Contract
Period
Projects Under Construction at March 31, 2026
Millers Branch
Phase II
Solar180Haskell County, TXSecond quarter 202615 years
Phase III
Solar
132Haskell County, TX
Fourth quarter 2026
15 years
Projects Completed During the Three Months Ended March 31, 2026
Millers Branch
Phase I
Solar200Haskell County, TXFebruary 202620 years
Project FacilityResource
Approximate Nameplate
Capacity
(MW)
Location
Projected
Completion Date
Projects Under Construction at March 31, 2026
Kay(*)
Wind
200
Kay County, OK
Third quarter 2026
Grant
Wind
152
Grant County, OK
Fourth quarter 2026
Grant Plains
Wind
147
Grant County, OK
Fourth quarter 2026
Wake
Wind
257
Crosby & Floyd Counties, TX
Second quarter 2027
BethelWind276Castro County, TXThird quarter 2027
(*)The facility has a total capacity of 299 MWs, of which 200 MWs is projected to be repowered and is contracted under a PPA. During the first quarter 2026 and subsequent to March 31, 2026, Southern Power placed 51 MWs of repowered capacity in service.
v3.26.1
Segment and Related Information (Tables)
 3 Months Ended
Mar. 31, 2026
Segment Reporting [Abstract]  
Schedule of Financial Data for Business Segments
Financial data for business segments for the three months ended March 31, 2026 and 2025 was as follows:
Electric Utilities
Traditional
Electric Operating
Companies		Southern
Power		EliminationsTotalSouthern Company Gas
Total Reportable Segments
All
Other		EliminationsConsolidated
(in millions)
Three Months Ended March 31, 2026
Operating revenues$5,482 $681 $(141)$6,022 $2,191 $8,213 $218 $(34)$8,397 
Other segment items(a)
2,857 442 (141)3,158 1,357 4,515 190 (40)4,665 
Depreciation and amortization(b)
942 278 — 1,220 183 1,403 17 — 1,420 
Earnings from equity method investments(1)— — (1)46 45 5 — 50 
Interest expense(c)
339 27 — 366 105 471 307 — 778 
Income taxes (benefit)230 (70)— 160 145 305 (77)— 228 
Segment net income (loss)(b)(c)(d)
$1,113 $4 $— $1,117 $447 $1,564 $(214)$6 $1,356 
At March 31, 2026
Goodwill$— $2 $— $2 $5,015 $5,017 $144 $— $5,161 
Total assets115,965 12,474 (849)127,590 27,551 155,141 2,684 (794)157,031 
Three Months Ended March 31, 2025
Operating revenues$5,311 $567 $(123)$5,755 $1,839 $7,594 $229 $(48)$7,775 
Other segment items(a)
2,794 303 (123)2,974 1,069 4,043 208 (58)4,193 
Depreciation and amortization(b)
947 152 — 1,099 169 1,268 18 — 1,286 
Earnings from equity method investments(2)— — (2)39 37 (4)(1)32 
Interest expense316 26 — 342 92 434 280 — 714 
Income taxes (benefit)226 (1)— 225 130 355 (75)— 280 
Segment net income (loss)(b)(d)
$1,026 $87 $— $1,113 $418 $1,531 $(206)$9 $1,334 
At December 31, 2025
Goodwill$— $2 $— $2 $5,015 $5,017 $144 $— $5,161 
Total assets114,287 12,657 (915)126,029 27,387 153,416 2,829 (525)155,720 
(a)Primarily consists of fuel, purchased power, cost of natural gas, cost of other sales, other operations and maintenance, taxes other than income taxes, AFUDC equity, non-service cost-related retirement benefits income, and net income (loss) attributable to noncontrolling interests.
(b)For Southern Power, includes accelerated depreciation related to the repowering of multiple wind facilities of $154 million ($120 million after tax) and $27 million ($20 million after tax, net of noncontrolling interest impacts) for the three months ended March 31, 2026 and 2025, respectively. See Note (K) under "Southern Power – Wind Repowering Projects" and Notes 5 and 15 to the financial statements under "Depreciation and Amortization – Southern Power" and "Southern Power – Wind Repowering Projects," respectively, in Item 8 of the Form 10-K for additional information.
(c)For All Other, includes a pre-tax loss of $11 million ($8 million after tax) associated with the extinguishment of debt at the parent company.
(d)Attributable to Southern Company.
Financial data for significant segment expenses and other segment information for the three months ended March 31, 2026 and 2025 was as follows:
Three Months Ended March 31,
20262025
(in millions)
Alabama Power
Operating revenues$2,092 $2,012 
Utility operations and maintenance
Rate RSE expenses301 365 
Rate CNP Compliance expenses74 75 
Total utility operations and maintenance375 440 
Other segment items(a)
667 608 
Depreciation and amortization381 370 
Interest expense115 108 
Income taxes129 111 
Segment net income$425 $375 
Capital expenditures$519 $560 
Georgia Power
Operating revenues$3,142 $3,037 
Utility operations and maintenance578 536 
Other segment items(a)
1,163 1,117 
Depreciation and amortization484 503 
Interest expense204 187 
Income taxes85 98 
Segment net income$628 $596 
Capital expenditures$2,070 $1,637 
Three Months Ended March 31,
20262025
(in millions)
Mississippi Power
Operating revenues$472 $420 
Operational expenses(b)
64 57 
Environmental compliance expenses(c)
4 2 
Other segment items(a)
251 218 
Depreciation and amortization55 52 
Interest expense20 20 
Income taxes18 16 
Segment net income
$60 $55 
Capital expenditures$82 $73 
(a)Primarily consists of fuel, purchased power, expenses from unregulated products and services, losses (gains) on asset dispositions, amortization of cloud software, taxes other than income taxes, AFUDC equity, and non-service cost-related retirement benefits income. For Mississippi Power, includes employee benefit expenses. Also includes earnings from equity method investments, which were immaterial for all periods presented.
(b)Consists of certain operations and maintenance expenses related to PEP and the MRA tariff, including labor costs, materials, contract services, and other normal operational costs. See Note (B) under "Mississippi Power" and Note 2 to the financial statements under "Mississippi Power" in Item 8 of the Form 10-K for additional information regarding PEP and the MRA tariff.
(c)Consists of environmental compliance expenses related to ECO Plan and the MRA tariff. See Note (B) under "Mississippi Power" and Note 2 to the financial statements under "Mississippi Power" in Item 8 of the Form 10-K for additional information regarding ECO Plan and the MRA tariff.
Financial data for segment information for the three months ended March 31, 2026 and 2025 was as follows:
Three Months Ended March 31,
20262025
(in millions)
Operating revenues
$681 $567 
Other segment items(a)
442 303 
Depreciation and amortization(b)
278 152 
Interest expense27 26 
Income taxes (benefit)(70)(1)
Segment net income(b)(c)
$4 $87 
(a)Primarily consists of fuel, purchased power, other operations and maintenance, taxes other than income taxes, and net income (loss) attributable to noncontrolling interests.
(b)For the three months ended March 31, 2026 and 2025, includes accelerated depreciation of $154 million ($120 million after tax) and $27 million ($20 million after tax, net of noncontrolling interest impacts), respectively, related to the repowering of the multiple wind facilities. See Note (K) under "Southern Power – Wind Repowering Projects" and Notes 5 and 15 to the financial statements under "Depreciation and Amortization – Southern Power" and "Southern Power – Wind Repowering Projects," respectively, in Item 8 of the Form 10-K for additional information.
(c)Southern Power had no earnings from equity method investments for any period presented.
Financial data for business segments for the three months ended March 31, 2026 and 2025 was as follows:
Gas Distribution OperationsGas
Pipeline Investments		Gas Marketing Services
Total Reportable Segments
All
Other
EliminationsConsolidated
(in millions)
Three Months Ended March 31, 2026
Operating revenues$1,900 $8 $285 $2,193 $2 $(4)$2,191 
Other segment items(*)
1,177 — 183 1,360 1 (4)1,357 
Depreciation and amortization179 1 2 182 1 — 183 
Earnings from equity method investments— 46 — 46 — — 46 
Interest expense91 9 1 101 4 — 105 
Income taxes (benefit)
116 11 28 155 (10)— 145 
Segment net income
$337 $33 $71 $441 $6 $— $447 
Total assets at March 31, 2026
$26,111 $1,517 $1,768 $29,396 $11,276 $(13,121)$27,551 
Three Months Ended March 31, 2025
Operating revenues$1,570 $8 $261 $1,839 $4 $(4)$1,839 
Other segment items(*)
905 1 166 1,072 1 (4)1,069 
Depreciation and amortization164 1 3 168 1 — 169 
Earnings from equity method investments— 39 — 39 — — 39 
Interest expense82 9 1 92 — — 92 
Income taxes (benefit)
104 9 26 139 (9)— 130 
Segment net income$315 $27 $65 $407 $11 $— $418 
Total assets at December 31, 2025
$25,391 $1,475 $1,749 $28,615 $10,643 $(11,871)$27,387 
(*)Primarily consists of cost of natural gas, other operations and maintenance, taxes other than income taxes, AFUDC equity, and non-service cost-related retirement benefits income.
v3.26.1
Introduction - Schedule of Goodwill (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Goodwill [Line Items]    
Goodwill $ 5,161 $ 5,161
SOUTHERN Co GAS    
Goodwill [Line Items]    
Goodwill 5,015 5,015
SOUTHERN Co GAS | Gas distribution operations    
Goodwill [Line Items]    
Goodwill 4,034 4,034
SOUTHERN Co GAS | Gas marketing services    
Goodwill [Line Items]    
Goodwill $ 981 $ 981
v3.26.1
Introduction - Schedule of Other Intangible Assets (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Subject to amortization:    
Gross Carrying Amount $ 669 $ 669
Accumulated Amortization (450) (444)
Other Intangible Assets, Net 219 225
Not subject to amortization:    
FCC licenses 75 75
Total other intangible assets    
Gross Carrying Amount 744 744
Accumulated Amortization (450) (444)
Other Intangible Assets, Net 294 300
Customer relationships    
Subject to amortization:    
Gross Carrying Amount 212 212
Accumulated Amortization (190) (189)
Other Intangible Assets, Net 22 23
Total other intangible assets    
Accumulated Amortization (190) (189)
Trade names    
Subject to amortization:    
Gross Carrying Amount 64 64
Accumulated Amortization (64) (64)
Other Intangible Assets, Net 0 0
Total other intangible assets    
Accumulated Amortization (64) (64)
PPA fair value adjustments    
Subject to amortization:    
Gross Carrying Amount 390 390
Accumulated Amortization (193) (188)
Other Intangible Assets, Net 197 202
Total other intangible assets    
Accumulated Amortization (193) (188)
Other    
Subject to amortization:    
Gross Carrying Amount 3 3
Accumulated Amortization (3) (3)
Other Intangible Assets, Net 0 0
Total other intangible assets    
Accumulated Amortization (3) (3)
SOUTHERN POWER CO    
Subject to amortization:    
Accumulated Amortization (193) (188)
Total other intangible assets    
Accumulated Amortization (193) (188)
SOUTHERN POWER CO | PPA fair value adjustments    
Subject to amortization:    
Gross Carrying Amount 390 390
Accumulated Amortization (193) (188)
Other Intangible Assets, Net 197 202
Total other intangible assets    
Accumulated Amortization (193) (188)
SOUTHERN Co GAS    
Subject to amortization:    
Gross Carrying Amount 182 182
Accumulated Amortization (180) (179)
Other Intangible Assets, Net 2 3
Total other intangible assets    
Accumulated Amortization (180) (179)
Other Intangible Assets, Net 2 3
SOUTHERN Co GAS | Customer relationships    
Subject to amortization:    
Gross Carrying Amount 156 156
Accumulated Amortization (154) (153)
Other Intangible Assets, Net 2 3
Total other intangible assets    
Accumulated Amortization (154) (153)
SOUTHERN Co GAS | Trade names    
Subject to amortization:    
Gross Carrying Amount 26 26
Accumulated Amortization (26) (26)
Other Intangible Assets, Net 0 0
Total other intangible assets    
Accumulated Amortization $ (26) $ (26)
v3.26.1
Introduction - Schedule of Amortization of Other Intangible Assets (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Finite-Lived Intangible Assets [Line Items]    
Amortization of intangible assets $ 7 $ 8
Decrease in operating revenues 5 5
SOUTHERN POWER CO    
Finite-Lived Intangible Assets [Line Items]    
Amortization of intangible assets 5 5
SOUTHERN Co GAS    
Finite-Lived Intangible Assets [Line Items]    
Amortization of intangible assets $ 1 $ 2
v3.26.1
Introduction - Schedule of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Mar. 31, 2025
Dec. 31, 2024
Restricted Cash and Cash Equivalent Item [Line Items]        
Cash and cash equivalents $ 981 $ 1,639    
Restricted cash:        
Total cash, cash equivalents, and restricted cash 987 1,640 $ 2,332 $ 1,101
Other current assets        
Restricted cash:        
Restricted cash 6 1    
GEORGIA POWER CO        
Restricted Cash and Cash Equivalent Item [Line Items]        
Cash and cash equivalents 24 59    
Restricted cash:        
Total cash, cash equivalents, and restricted cash 24 59 383 118
SOUTHERN POWER CO        
Restricted Cash and Cash Equivalent Item [Line Items]        
Cash and cash equivalents 72 105    
Restricted cash:        
Total cash, cash equivalents, and restricted cash 72 105 192 168
SOUTHERN Co GAS        
Restricted Cash and Cash Equivalent Item [Line Items]        
Cash and cash equivalents 137 15    
Restricted cash:        
Total cash, cash equivalents, and restricted cash 142 15 $ 87 $ 44
SOUTHERN Co GAS | Other current assets        
Restricted cash:        
Restricted cash 5 0    
Southern Holdings Company | Collateral For Life Insurance And Long-Term Disability Insurance        
Restricted cash:        
Restricted cash $ 1 $ 1    
v3.26.1
Regulatory Matters - Schedule of Cost Recovery Clauses (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
ALABAMA POWER CO | Other regulatory assets, deferred    
Loss Contingencies [Line Items]    
Rate ECR $ 200 $ 146
ALABAMA POWER CO | Other regulatory liabilities, deferred    
Loss Contingencies [Line Items]    
Liability for Unpaid Claims and Claims Adjustment Expense, Net 52 60
GEORGIA POWER CO | Other regulatory assets, current | Property Damage Reserve Asset    
Loss Contingencies [Line Items]    
Regulatory asset balance related to storm damage 31 31
GEORGIA POWER CO | Other regulatory assets, deferred | Property Damage Reserve Asset    
Loss Contingencies [Line Items]    
Regulatory asset balance related to storm damage 962 880
GEORGIA POWER CO | Receivables – under recovered retail fuel clause revenues    
Loss Contingencies [Line Items]    
Fuel cost recovery 234 310
GEORGIA POWER CO | Deferred under recovered retail fuel clause revenues    
Loss Contingencies [Line Items]    
Fuel cost recovery 210 212
MISSISSIPPI POWER CO | Wholesale MB    
Loss Contingencies [Line Items]    
Fuel cost recovery 0 0
MISSISSIPPI POWER CO | Other regulatory assets, deferred | Retail electric revenues    
Loss Contingencies [Line Items]    
Property damage reserve 57 57
MISSISSIPPI POWER CO | Deferred under recovered retail fuel clause revenues    
Loss Contingencies [Line Items]    
Fuel cost recovery 0 40
MISSISSIPPI POWER CO | Receivables – customer accounts, net    
Loss Contingencies [Line Items]    
Fuel cost recovery 55 0
MISSISSIPPI POWER CO | Other current assets | Wholesale MRA    
Loss Contingencies [Line Items]    
Fuel cost recovery 9 6
SOUTHERN Co GAS | Natural gas cost over recovery    
Loss Contingencies [Line Items]    
Natural gas cost under recovery $ 131 $ 158
v3.26.1
Regulatory Matters - Alabama Power (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Dec. 31, 2026
Dec. 31, 2025
Loss Contingencies [Line Items]      
In service $ 149,086   $ 146,114
ALABAMA POWER CO      
Loss Contingencies [Line Items]      
In service 40,185   38,915
ALABAMA POWER CO | Plant Barry Unit 5      
Loss Contingencies [Line Items]      
In service 307    
SOUTHERN POWER CO      
Loss Contingencies [Line Items]      
In service 15,342   $ 15,034
SOUTHERN POWER CO | Plant Barry Unit 5      
Loss Contingencies [Line Items]      
In service 307    
Reliability Reserve Liability | ALABAMA POWER CO      
Loss Contingencies [Line Items]      
Remaining net book value 163    
Reliability reserve expense $ 21    
Reliability Reserve Liability | ALABAMA POWER CO | Scenario, Forecast      
Loss Contingencies [Line Items]      
Reliability reserve expense   $ 60  
v3.26.1
Regulatory Matters - Georgia Power (Details) - GEORGIA POWER CO
$ in Millions
 3 Months Ended
Apr. 23, 2026
MW
Mar. 25, 2026
MW
Dec. 19, 2025
MW
May 14, 2025
USD ($)
Mar. 31, 2026
USD ($)
MW
Public Utilities, General Disclosures [Line Items]          
Capital costs | $         $ 3,700
Total certified amounts | $         $ 19,500
Approved capacity increase (in MWs)     9,885    
Generating capacity petitioned for decertification   757      
Robins          
Public Utilities, General Disclosures [Line Items]          
Nameplate capacity placed in service         128
Minimum | Subsequent Event          
Public Utilities, General Disclosures [Line Items]          
Requested additional generating capacity (in MWs) 2,000        
Maximum          
Public Utilities, General Disclosures [Line Items]          
Approved rate increase (decrease) | $       $ 200  
Maximum | Subsequent Event          
Public Utilities, General Disclosures [Line Items]          
Requested additional generating capacity (in MWs) 6,000        
v3.26.1
Regulatory Matters - Georgia Power, Projects Under Construction (Details) - GEORGIA POWER CO - MW
Apr. 29, 2026
Mar. 31, 2026
McGrau Ford    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   265
Twiggs County    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   200
Wadley    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   260
Plant Bowen, Phase 1    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   250
Plant Bowen, Phase 2    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   250
South Hall    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   250
Plant Wansley    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   500
Plant Yates, Phase 1    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   320
Plant Yates, Phase 2    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   250
Thomson    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   500
Hammond Phase 2    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   193
Plant McIntosh    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   250
Various Facilities    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   372
Laurens County    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   200
Plant Mitchell    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   150
Plant Bowen Unit 7    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   741
Plant Bowen Unit 8    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   741
Plant McIntosh Unit 12    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   757
Plant Wansley Unit 10    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   727
Plant Wansley Unit 11    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   727
Plant Yates Unit 8    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   442
Plant Yates Unit 9    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   442
Plant Yates Unit 10    
Public Utilities, General Disclosures [Line Items]    
Approximate nameplate capacity   442
Robins    
Public Utilities, General Disclosures [Line Items]    
Nameplate capacity placed in service   128
Moody | Subsequent Event    
Public Utilities, General Disclosures [Line Items]    
Nameplate capacity placed in service 50  
v3.26.1
Regulatory Matters - Mississippi Power (Details) - MISSISSIPPI POWER CO - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Apr. 14, 2026
Mar. 02, 2026
Jun. 17, 2025
Mar. 31, 2026
Dec. 31, 2026
Plant Daniel Unit 1          
Loss Contingencies [Line Items]          
Remaining net book value       $ 124.0  
Reliability Reserve Liability          
Loss Contingencies [Line Items]          
Reliability reserve expense       6.0  
Remaining net book value       $ 52.0  
Reliability Reserve Liability | Scenario, Forecast          
Loss Contingencies [Line Items]          
Reliability reserve expense         $ 8.0
Mississippi PSC PEP Filing          
Loss Contingencies [Line Items]          
Requested revenues increase (decrease) percentage     1.80%    
Requested rate increase amount     $ 20.0    
Mississippi PSC | Subsequent Event          
Loss Contingencies [Line Items]          
Approved rate increase (decrease) $ 2.0        
Mississippi PSC SRR Filing          
Loss Contingencies [Line Items]          
Requested rate increase amount   $ 13.7      
Minimum annual accrual, amount   $ 13.5      
v3.26.1
Contingencies - Environmental Remediation (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
GEORGIA POWER CO    
Loss Contingencies [Line Items]    
Environmental remediation liability, current and former sites $ 14 $ 14
SOUTHERN Co GAS    
Loss Contingencies [Line Items]    
Environmental remediation liability, current and former sites $ 219 $ 227
v3.26.1
Revenue from Contracts with Customers and Lease Income - Schedule of Disaggregation of Revenue (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers $ 8,040 $ 7,591
Total operating revenues 8,397 7,775
Residential    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 2,003 2,065
Commercial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,663 1,612
Industrial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 942 915
Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 31 31
Retail electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 4,639 4,623
Natural gas distribution revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,890 1,580
Residential    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,028 845
Commercial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 253 199
Transportation    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 440 406
Industrial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 24 18
Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 145 112
Wholesale electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 734 635
PPA energy revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 496 415
PPA capacity revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 149 149
Non-PPA revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 89 71
Other natural gas revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 284 260
Gas marketing services    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 281 256
Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 3 4
Other revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 493 493
Other revenue sources    
Disaggregation of Revenue [Line Items]    
Other revenues 357 184
ALABAMA POWER CO    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,928 1,914
Total operating revenues 2,092 2,012
ALABAMA POWER CO | Residential    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 773 805
ALABAMA POWER CO | Commercial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 477 482
ALABAMA POWER CO | Industrial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 414 390
ALABAMA POWER CO | Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 3 3
ALABAMA POWER CO | Retail electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,667 1,680
ALABAMA POWER CO | Wholesale electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 183 151
ALABAMA POWER CO | PPA energy revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 46 54
ALABAMA POWER CO | PPA capacity revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 18 28
ALABAMA POWER CO | Non-PPA revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 119 69
ALABAMA POWER CO | Other revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 78 83
ALABAMA POWER CO | Other revenue sources    
Disaggregation of Revenue [Line Items]    
Other revenues 164 98
GEORGIA POWER CO    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 3,105 3,073
Total operating revenues 3,142 3,037
GEORGIA POWER CO | Residential    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,150 1,186
GEORGIA POWER CO | Commercial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,104 1,055
GEORGIA POWER CO | Industrial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 438 444
GEORGIA POWER CO | Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 25 26
GEORGIA POWER CO | Retail electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 2,717 2,711
GEORGIA POWER CO | Wholesale electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 152 132
GEORGIA POWER CO | PPA energy revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 64 84
GEORGIA POWER CO | PPA capacity revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 44 39
GEORGIA POWER CO | Non-PPA revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 44 9
GEORGIA POWER CO | Other revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 236 230
GEORGIA POWER CO | Other revenue sources    
Disaggregation of Revenue [Line Items]    
Other revenues 37 (36)
MISSISSIPPI POWER CO    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 464 406
Total operating revenues 472 420
MISSISSIPPI POWER CO | Residential    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 80 74
MISSISSIPPI POWER CO | Commercial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 82 75
MISSISSIPPI POWER CO | Industrial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 90 81
MISSISSIPPI POWER CO | Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 3 2
MISSISSIPPI POWER CO | Retail electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 255 232
MISSISSIPPI POWER CO | Wholesale electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 194 154
MISSISSIPPI POWER CO | PPA energy revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 4 3
MISSISSIPPI POWER CO | PPA capacity revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 21 17
MISSISSIPPI POWER CO | Non-PPA revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 169 134
MISSISSIPPI POWER CO | Other revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 15 20
MISSISSIPPI POWER CO | Other revenue sources    
Disaggregation of Revenue [Line Items]    
Other revenues 8 14
SOUTHERN POWER CO    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 523 432
Total operating revenues 681 567
SOUTHERN POWER CO | Residential    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 0 0
SOUTHERN POWER CO | Commercial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 0 0
SOUTHERN POWER CO | Industrial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 0 0
SOUTHERN POWER CO | Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 0 0
SOUTHERN POWER CO | Retail electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 0 0
SOUTHERN POWER CO | Wholesale electric revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 519 428
SOUTHERN POWER CO | PPA energy revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 392 284
SOUTHERN POWER CO | PPA capacity revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 83 82
SOUTHERN POWER CO | Non-PPA revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 44 62
SOUTHERN POWER CO | Other revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 4 4
SOUTHERN POWER CO | Other revenue sources    
Disaggregation of Revenue [Line Items]    
Other revenues 158 135
SOUTHERN Co GAS    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 2,174 1,840
Total operating revenues 2,191 1,839
SOUTHERN Co GAS | Natural gas distribution revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,890 1,580
SOUTHERN Co GAS | Residential    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 1,028 845
SOUTHERN Co GAS | Commercial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 253 199
SOUTHERN Co GAS | Transportation    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 440 406
SOUTHERN Co GAS | Industrial    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 24 18
SOUTHERN Co GAS | Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 145 112
SOUTHERN Co GAS | Other natural gas revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 284 260
SOUTHERN Co GAS | Gas marketing services    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 281 256
SOUTHERN Co GAS | Other    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 3 4
SOUTHERN Co GAS | Other revenues    
Disaggregation of Revenue [Line Items]    
Total revenue from contracts with customers 0 0
SOUTHERN Co GAS | Other revenue sources    
Disaggregation of Revenue [Line Items]    
Other revenues $ 17 $ (1)
v3.26.1
Revenue from Contracts with Customers and Lease Income - Schedule of Contract Balances (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Disaggregation of Revenue [Line Items]    
Accounts Receivable $ 3,083 $ 3,139
Contract Assets 338 294
Contract Liabilities 257 213
ALABAMA POWER CO    
Disaggregation of Revenue [Line Items]    
Accounts Receivable 649 716
Contract Assets 5 3
Contract Liabilities 9 6
GEORGIA POWER CO    
Disaggregation of Revenue [Line Items]    
Accounts Receivable 1,179 1,278
Contract Assets 196 160
Contract Liabilities 76 75
MISSISSIPPI POWER CO    
Disaggregation of Revenue [Line Items]    
Accounts Receivable 119 115
Contract Assets 0 0
Contract Liabilities 2 0
SOUTHERN POWER CO    
Disaggregation of Revenue [Line Items]    
Accounts Receivable 94 132
Contract Assets 0 0
Contract Liabilities 1 2
SOUTHERN Co GAS    
Disaggregation of Revenue [Line Items]    
Accounts Receivable 925 864
Contract Assets 67 67
Contract Liabilities $ 0 $ 0
v3.26.1
Revenue from Contracts with Customers and Lease Income - Narrative (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Disaggregation of Revenue [Line Items]    
Contract liabilities $ 257 $ 213
Contract assets 338 294
Revenue from contracts with customers recognized 55  
GEORGIA POWER CO    
Disaggregation of Revenue [Line Items]    
Contract liabilities 76 75
Contract assets 196 160
Revenue from contracts with customers recognized 11  
SOUTHERN Co GAS    
Disaggregation of Revenue [Line Items]    
Contract liabilities 0 0
Contract assets 67 67
Revenue from contracts with customers recognized 0  
ALABAMA POWER CO    
Disaggregation of Revenue [Line Items]    
Contract liabilities 9 6
Contract assets 5 3
Revenue from contracts with customers recognized 0  
MISSISSIPPI POWER CO    
Disaggregation of Revenue [Line Items]    
Contract liabilities 2 0
Contract assets 0 0
Revenue from contracts with customers recognized 0  
SOUTHERN POWER CO    
Disaggregation of Revenue [Line Items]    
Contract liabilities 1 2
Contract assets 0 0
Revenue from contracts with customers recognized $ 0  
Retail Customer Fixed Bill Programs | GEORGIA POWER CO    
Disaggregation of Revenue [Line Items]    
Contract term 1 year  
Energy Efficiency Enhancement And Upgrade | SOUTHERN Co GAS    
Disaggregation of Revenue [Line Items]    
Contract liabilities $ 68  
Unregulated Distributed Generation    
Disaggregation of Revenue [Line Items]    
Contract liabilities 170 132
Contract assets $ 69 $ 63
v3.26.1
Revenue from Contracts with Customers and Lease Income - Schedule of Remaining Performance Obligations (Details)
$ in Millions
Mar. 31, 2026
USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-04-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 875
Performance obligation, expected timing of satisfaction 9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 679
Performance obligation, expected timing of satisfaction 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 452
Performance obligation, expected timing of satisfaction 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 412
Performance obligation, expected timing of satisfaction 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2030-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 416
Performance obligation, expected timing of satisfaction 1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 3,130
Performance obligation, expected timing of satisfaction
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-04-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 8
Performance obligation, expected timing of satisfaction 9 months
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 5
Performance obligation, expected timing of satisfaction 1 year
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 4
Performance obligation, expected timing of satisfaction 1 year
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 2
Performance obligation, expected timing of satisfaction 1 year
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2030-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 1
Performance obligation, expected timing of satisfaction 1 year
ALABAMA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 6
Performance obligation, expected timing of satisfaction
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-04-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 48
Performance obligation, expected timing of satisfaction 9 months
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 60
Performance obligation, expected timing of satisfaction 1 year
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 43
Performance obligation, expected timing of satisfaction 1 year
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 22
Performance obligation, expected timing of satisfaction 1 year
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2030-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 22
Performance obligation, expected timing of satisfaction 1 year
GEORGIA POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 146
Performance obligation, expected timing of satisfaction
MISSISSIPPI POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-04-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 49
Performance obligation, expected timing of satisfaction 9 months
MISSISSIPPI POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 69
Performance obligation, expected timing of satisfaction 1 year
MISSISSIPPI POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 73
Performance obligation, expected timing of satisfaction 1 year
MISSISSIPPI POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 12
Performance obligation, expected timing of satisfaction 1 year
MISSISSIPPI POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2030-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 0
Performance obligation, expected timing of satisfaction 1 year
MISSISSIPPI POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 0
Performance obligation, expected timing of satisfaction
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-04-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 270
Performance obligation, expected timing of satisfaction 9 months
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 349
Performance obligation, expected timing of satisfaction 1 year
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 389
Performance obligation, expected timing of satisfaction 1 year
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 393
Performance obligation, expected timing of satisfaction 1 year
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2030-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 393
Performance obligation, expected timing of satisfaction 1 year
SOUTHERN POWER CO | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 2,978
Performance obligation, expected timing of satisfaction
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-04-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 31
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation 21
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation 0
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation 0
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2030-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation 0
SOUTHERN Co GAS | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Revenue, remaining performance obligation $ 0
v3.26.1
Revenue from Contracts with Customers and Lease Income - Schedule of Lease Income (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Lessor, Lease, Description [Line Items]    
Lease income - interest income on sales-type leases $ 5 $ 6
Lease income - operating leases 34 33
Variable lease income 79 81
Total lease income 118 120
ALABAMA POWER CO    
Lessor, Lease, Description [Line Items]    
Lease income - interest income on sales-type leases 0 0
Lease income - operating leases 3 2
Variable lease income 0 0
Total lease income 3 2
GEORGIA POWER CO    
Lessor, Lease, Description [Line Items]    
Lease income - interest income on sales-type leases 0 0
Lease income - operating leases 7 7
Variable lease income 0 0
Total lease income 7 7
MISSISSIPPI POWER CO    
Lessor, Lease, Description [Line Items]    
Lease income - interest income on sales-type leases 3 4
Lease income - operating leases 1 1
Variable lease income 0 0
Total lease income 4 5
SOUTHERN POWER CO    
Lessor, Lease, Description [Line Items]    
Lease income - interest income on sales-type leases 2 2
Lease income - operating leases 37 37
Variable lease income 87 89
Total lease income 126 128
SOUTHERN Co GAS    
Lessor, Lease, Description [Line Items]    
Lease income - interest income on sales-type leases 0 0
Lease income - operating leases 9 9
Variable lease income 0 0
Total lease income $ 9 $ 9
v3.26.1
Consolidated Entities and Equity Method Investments - Narrative (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Schedule of Equity Method Investments [Line Items]      
Equity investments in unconsolidated subsidiaries $ 1,365   $ 1,318
Earnings from equity method investments 50 $ 32  
Assets 157,031   155,720
Liabilities 117,119   116,853
Southern Holdings Company      
Schedule of Equity Method Investments [Line Items]      
Equity investments in unconsolidated subsidiaries 125   124
Earnings from equity method investments 0 0  
SOUTHERN POWER CO      
Schedule of Equity Method Investments [Line Items]      
Earnings from equity method investments 0 0  
Assets 12,474   12,657
Liabilities 6,080   6,136
SOUTHERN Co GAS      
Schedule of Equity Method Investments [Line Items]      
Equity investments in unconsolidated subsidiaries 1,224   1,182
Earnings from equity method investments 46 39  
Assets 27,551   27,387
Liabilities 16,118   16,260
SOUTHERN Co GAS | Other      
Schedule of Equity Method Investments [Line Items]      
Equity investments in unconsolidated subsidiaries 34   34
Earnings from equity method investments $ 0 $ 0  
SP Solar Holdings I, LP | SOUTHERN POWER CO      
Schedule of Equity Method Investments [Line Items]      
Distribution made to limited partner, cash distributions paid, percentage 67.00%    
SP Solar Holdings I, LP | Financial Investors      
Schedule of Equity Method Investments [Line Items]      
Distribution made to limited partner, cash distributions paid, percentage 33.00%    
Variable Interest Entity, Primary Beneficiary | SP Solar Holdings I, LP | SOUTHERN POWER CO      
Schedule of Equity Method Investments [Line Items]      
Assets $ 5,100   5,200
Liabilities 361   360
Noncontrolling interests related to other partners' interests 899   918
Variable Interest Entity, Primary Beneficiary | Other Variable Interest Entities | SOUTHERN POWER CO      
Schedule of Equity Method Investments [Line Items]      
Assets 1,600   1,600
Liabilities 246   236
Noncontrolling interests related to other partners' interests $ 590   $ 617
v3.26.1
Consolidated Entities and Equity Method Investments - Schedule of Equity Method Investments (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Schedule of Equity Method Investments [Line Items]    
Investment Balance $ 1,365 $ 1,318
SOUTHERN Co GAS    
Schedule of Equity Method Investments [Line Items]    
Investment Balance 1,224 1,182
SOUTHERN Co GAS | SNG    
Schedule of Equity Method Investments [Line Items]    
Investment Balance 1,190 1,148
SOUTHERN Co GAS | Other    
Schedule of Equity Method Investments [Line Items]    
Investment Balance $ 34 $ 34
v3.26.1
Consolidated Entities and Equity Method Investments - Schedule of Earnings (Loss) from Equity Method Investments (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Schedule of Equity Method Investments [Line Items]      
Earnings from equity method investments $ 50 $ 32  
Equity investments in unconsolidated subsidiaries 1,365   $ 1,318
SOUTHERN Co GAS      
Schedule of Equity Method Investments [Line Items]      
Earnings from equity method investments 46 39  
Equity investments in unconsolidated subsidiaries 1,224   1,182
SOUTHERN Co GAS | SNG      
Schedule of Equity Method Investments [Line Items]      
Earnings from equity method investments 46 39  
Equity investments in unconsolidated subsidiaries 1,190   1,148
SOUTHERN Co GAS | Other      
Schedule of Equity Method Investments [Line Items]      
Earnings from equity method investments 0 0  
Equity investments in unconsolidated subsidiaries 34   34
Southern Holdings Company      
Schedule of Equity Method Investments [Line Items]      
Earnings from equity method investments 0 $ 0  
Equity investments in unconsolidated subsidiaries $ 125   $ 124
v3.26.1
Financing - Schedule of Credit Arrangements (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Feb. 20, 2026
Mar. 31, 2025
Line of Credit Facility [Line Items]      
2026 $ 45    
2028 500    
2029 775    
2030 2,300    
2031 5,300    
Total 8,920    
Unused 8,909    
Expires within One Year 45    
Southern Company parent      
Line of Credit Facility [Line Items]      
2026 0    
2028 500    
2029 0    
2030 0    
2031 2,500    
Total 3,000    
Unused 2,999    
Expires within One Year 0    
ALABAMA POWER CO      
Line of Credit Facility [Line Items]      
2026 15    
2028 0    
2029 650    
2030 700    
2031 0    
Total 1,365    
Unused 1,365    
Expires within One Year 15    
ALABAMA POWER CO | FFB Credit Facility      
Line of Credit Facility [Line Items]      
Total   $ 4,100  
GEORGIA POWER CO      
Line of Credit Facility [Line Items]      
2026 0    
2028 0    
2029 0    
2030 0    
2031 2,050    
Total 2,050    
Unused 2,042    
Expires within One Year 0    
GEORGIA POWER CO | Uncommited Letter Of Credit Facility      
Line of Credit Facility [Line Items]      
Letters of credit outstanding 26    
GEORGIA POWER CO | FFB Credit Facility      
Line of Credit Facility [Line Items]      
Total   $ 22,400  
MISSISSIPPI POWER CO      
Line of Credit Facility [Line Items]      
2026 0    
2028 0    
2029 125    
2030 0    
2031 150    
Total 275    
Unused 275    
Expires within One Year 0    
SOUTHERN POWER CO      
Line of Credit Facility [Line Items]      
2026 0    
2028 0    
2029 0    
2030 0    
2031 600    
Total 600    
Unused 600    
Expires within One Year 0    
SOUTHERN POWER CO | Continuing Letter of Credit Facility A      
Line of Credit Facility [Line Items]      
Total 75    
Unused 17    
SOUTHERN POWER CO | Continuing Letter of Credit Facility B      
Line of Credit Facility [Line Items]      
Total 100    
Unused 4    
SOUTHERN POWER CO | Uncommited Letter Of Credit Facility      
Line of Credit Facility [Line Items]      
Letters of credit outstanding 23    
SOUTHERN Co GAS      
Line of Credit Facility [Line Items]      
2026 0    
2028 0    
2029 0    
2030 1,600    
2031 0    
Total 1,600    
Unused 1,598    
Expires within One Year 0    
SEGCO      
Line of Credit Facility [Line Items]      
2026 30    
2028 0    
2029 0    
2030 0    
2031 0    
Total 30    
Unused 30    
Expires within One Year 30    
Southern Company, Southern Power, And Mississippi Power      
Line of Credit Facility [Line Items]      
Total     $ 3,250
Alabama Property Company      
Line of Credit Facility [Line Items]      
2026 15    
Unused 15    
Southern Company Gas Capital      
Line of Credit Facility [Line Items]      
2031 800    
Nicor Gas      
Line of Credit Facility [Line Items]      
2031 $ 800    
v3.26.1
Financing - Bank Credit Agreements Narrative (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Mar. 31, 2025
Debt Instrument [Line Items]    
Line of credit facility, maximum borrowing capacity $ 8,920  
Variable rate pollution control revenue bonds outstanding 1,500  
Southern Company, Southern Power, And Mississippi Power    
Debt Instrument [Line Items]    
Line of credit facility, maximum borrowing capacity   $ 3,250
ALABAMA POWER CO    
Debt Instrument [Line Items]    
Line of credit facility, maximum borrowing capacity 1,365  
Variable rate pollution control revenue bonds outstanding 796  
Fixed rate pollution control revenue bonds outstanding 160  
GEORGIA POWER CO    
Debt Instrument [Line Items]    
Line of credit facility, maximum borrowing capacity 2,050  
Variable rate pollution control revenue bonds outstanding 667  
Fixed rate pollution control revenue bonds outstanding 325  
MISSISSIPPI POWER CO    
Debt Instrument [Line Items]    
Line of credit facility, maximum borrowing capacity 275  
Variable rate pollution control revenue bonds outstanding $ 58  
v3.26.1
Financing - DOE Loan Guarantee Borrowings (Details) - USD ($)
$ in Millions
 1 Months Ended 3 Months Ended
Feb. 20, 2026
Mar. 31, 2026
Mar. 31, 2026
Line of Credit Facility [Line Items]      
Line of credit facility, maximum borrowing capacity   $ 8,920 $ 8,920
GEORGIA POWER CO      
Line of Credit Facility [Line Items]      
Line of credit facility, maximum borrowing capacity   $ 2,050 $ 2,050
GEORGIA POWER CO | FFB Credit Facility      
Line of Credit Facility [Line Items]      
Borrower reimbursement, maximum percentage of eligible project costs 80.00%    
Line of credit facility, maximum borrowing capacity $ 22,400    
Interest rate   5.041% 5.041%
Debt Instrument, Basis Spread on Variable Rate     0.375%
Prepayment requirement, percentage of total advances made to borrower, minimum threshold 95.00%    
Mandatory prepayment, percentage of principal to be prepaid 100.00%    
Proceeds from Lines of Credit   $ 1,000  
GEORGIA POWER CO | FFB Credit Facility | Minimum      
Line of Credit Facility [Line Items]      
Mandatory prepayment, payable period 1 year    
GEORGIA POWER CO | FFB Credit Facility | Maximum      
Line of Credit Facility [Line Items]      
Mandatory prepayment, payable period 5 years    
ALABAMA POWER CO      
Line of Credit Facility [Line Items]      
Line of credit facility, maximum borrowing capacity   $ 1,365 $ 1,365
ALABAMA POWER CO | FFB Credit Facility      
Line of Credit Facility [Line Items]      
Borrower reimbursement, maximum percentage of eligible project costs 80.00%    
Line of credit facility, maximum borrowing capacity $ 4,100    
Debt Instrument, Basis Spread on Variable Rate     0.375%
Prepayment requirement, percentage of total advances made to borrower, minimum threshold 95.00%    
Mandatory prepayment, percentage of principal to be prepaid 100.00%    
ALABAMA POWER CO | FFB Credit Facility | Minimum      
Line of Credit Facility [Line Items]      
Mandatory prepayment, payable period 1 year    
ALABAMA POWER CO | FFB Credit Facility | Maximum      
Line of Credit Facility [Line Items]      
Mandatory prepayment, payable period 3 years    
v3.26.1
Financing - Equity Distribution Agreement (Details) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 11 Months Ended 12 Months Ended
Mar. 31, 2026
Mar. 02, 2026
Mar. 31, 2026
Mar. 31, 2025
Sep. 30, 2025
Dec. 31, 2025
Line of Credit Facility [Line Items]            
Number of shares authorized (in shares) 27,398,371          
Proceeds from issuance of common stock     $ 535 $ 30    
Forward Sale Contract 1            
Line of Credit Facility [Line Items]            
Common stock issued to settle purchase contracts (in shares)   3,255,866 1,467,305     3,255,866
Forward price (in dollars per share)   $ 89.2443 $ 96.3883     $ 89.4692
Forward Sale Contract 2            
Line of Credit Facility [Line Items]            
Common stock issued to settle purchase contracts (in shares)   2,314,487 1,896,549     2,314,487
Forward price (in dollars per share)   $ 92.8723 $ 97.5815     $ 92.7805
Forward Sale Contract 3            
Line of Credit Facility [Line Items]            
Common stock issued to settle purchase contracts (in shares)     1,903,317      
Forward price (in dollars per share)     $ 95.5086      
Private Placement            
Line of Credit Facility [Line Items]            
Common stock issued to settle purchase contracts (in shares)     5,570,353      
Number of shares authorized (in shares)         49,885,779  
Proceeds from issuance of common stock     $ 506      
v3.26.1
Financing - Earnings Per Share (Details) - shares
shares in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Debt Disclosure [Abstract]    
As reported shares (in shares) 1,124 1,100
Effect of stock-based compensation (in shares) 4 5
Diluted (in shares) 1,128 1,105
v3.26.1
Income Taxes (Details) - USD ($)
$ in Millions
 1 Months Ended 3 Months Ended
Apr. 29, 2026
Mar. 31, 2026
Mar. 31, 2025
Income Tax Contingency [Line Items]      
Effective tax (benefit) rate   14.50% 18.10%
GEORGIA POWER CO      
Income Tax Contingency [Line Items]      
Payment for PTCs   $ 45  
Effective tax (benefit) rate   11.90% 14.20%
GEORGIA POWER CO | Subsequent Event      
Income Tax Contingency [Line Items]      
Sale of investment tax credit $ 33    
SOUTHERN POWER CO      
Income Tax Contingency [Line Items]      
Effective tax (benefit) rate   82.60% (5.30%)
SOUTHERN POWER CO | Subsequent Event      
Income Tax Contingency [Line Items]      
Sale of investment tax credit 12    
ALABAMA POWER CO | Subsequent Event      
Income Tax Contingency [Line Items]      
Sale of investment tax credit $ 6    
v3.26.1
Retirement Benefits (Details) - USD ($)
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2026
Pension Plans      
Pension Plans and Postretirement Plans      
Service cost $ 69,000,000 $ 66,000,000  
Interest cost 162,000,000 166,000,000  
Expected return on plan assets (322,000,000) (320,000,000)  
Amortization:      
Prior service costs 0 0  
Regulatory asset 0 0  
Net gain 18,000,000 9,000,000  
Net periodic pension income (73,000,000) (79,000,000)  
Pension Plans | Scenario, Forecast      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, expected future employer contributions, remainder of fiscal year     $ 0
Pension Plans | ALABAMA POWER CO      
Pension Plans and Postretirement Plans      
Service cost 15,000,000 15,000,000  
Interest cost 38,000,000 39,000,000  
Expected return on plan assets (79,000,000) (78,000,000)  
Amortization:      
Prior service costs 0 0  
Regulatory asset 0 0  
Net gain 5,000,000 2,000,000  
Net periodic pension income (21,000,000) (22,000,000)  
Pension Plans | GEORGIA POWER CO      
Pension Plans and Postretirement Plans      
Service cost 17,000,000 16,000,000  
Interest cost 47,000,000 49,000,000  
Expected return on plan assets (99,000,000) (99,000,000)  
Amortization:      
Prior service costs 0 0  
Regulatory asset 0 0  
Net gain 6,000,000 4,000,000  
Net periodic pension income (29,000,000) (30,000,000)  
Pension Plans | MISSISSIPPI POWER CO      
Pension Plans and Postretirement Plans      
Service cost 3,000,000 3,000,000  
Interest cost 7,000,000 7,000,000  
Expected return on plan assets (15,000,000) (15,000,000)  
Amortization:      
Prior service costs 0 0  
Regulatory asset 0 0  
Net gain 1,000,000 1,000,000  
Net periodic pension income (4,000,000) (4,000,000)  
Pension Plans | SOUTHERN POWER CO      
Pension Plans and Postretirement Plans      
Service cost 2,000,000 1,000,000  
Interest cost 2,000,000 2,000,000  
Expected return on plan assets (4,000,000) (4,000,000)  
Amortization:      
Prior service costs 0 0  
Regulatory asset 0 0  
Net gain 0 1,000,000  
Net periodic pension income 0 0  
Pension Plans | SOUTHERN Co GAS      
Pension Plans and Postretirement Plans      
Service cost 7,000,000 7,000,000  
Interest cost 11,000,000 11,000,000  
Expected return on plan assets (21,000,000) (22,000,000)  
Amortization:      
Prior service costs (1,000,000) (1,000,000)  
Regulatory asset 3,000,000 4,000,000  
Net gain 0 0  
Net periodic pension income (1,000,000) (1,000,000)  
Postretirement Benefits      
Pension Plans and Postretirement Plans      
Service cost 3,000,000 3,000,000  
Interest cost 16,000,000 17,000,000  
Expected return on plan assets (23,000,000) (23,000,000)  
Amortization:      
Prior service costs 1,000,000 1,000,000  
Regulatory asset   0  
Net gain (2,000,000) (3,000,000)  
Net periodic pension income (5,000,000) (5,000,000)  
Postretirement Benefits | ALABAMA POWER CO      
Pension Plans and Postretirement Plans      
Service cost 1,000,000 1,000,000  
Interest cost 4,000,000 4,000,000  
Expected return on plan assets (9,000,000) (9,000,000)  
Amortization:      
Prior service costs 0 0  
Regulatory asset   0  
Net gain 0 0  
Net periodic pension income (4,000,000) (4,000,000)  
Postretirement Benefits | GEORGIA POWER CO      
Pension Plans and Postretirement Plans      
Service cost 1,000,000 1,000,000  
Interest cost 6,000,000 6,000,000  
Expected return on plan assets (8,000,000) (8,000,000)  
Amortization:      
Prior service costs 0 0  
Regulatory asset   0  
Net gain 0 0  
Net periodic pension income (1,000,000) (1,000,000)  
Postretirement Benefits | MISSISSIPPI POWER CO      
Pension Plans and Postretirement Plans      
Service cost 0 0  
Interest cost 1,000,000 1,000,000  
Expected return on plan assets (1,000,000) 0  
Amortization:      
Prior service costs 0 0  
Regulatory asset   0  
Net gain 0 (1,000,000)  
Net periodic pension income 0 0  
Postretirement Benefits | SOUTHERN POWER CO      
Pension Plans and Postretirement Plans      
Service cost 0 0  
Interest cost 0 0  
Expected return on plan assets 0 0  
Amortization:      
Prior service costs 0 0  
Regulatory asset   0  
Net gain 0 0  
Net periodic pension income 0 0  
Postretirement Benefits | SOUTHERN Co GAS      
Pension Plans and Postretirement Plans      
Service cost 0 0  
Interest cost 2,000,000 2,000,000  
Expected return on plan assets (2,000,000) (2,000,000)  
Amortization:      
Prior service costs 0 0  
Regulatory asset   2,000,000  
Net gain (2,000,000) (2,000,000)  
Net periodic pension income $ (2,000,000) $ 0  
v3.26.1
Fair Value Measurements - Schedule of Assets and Liabilities Measured at Fair Value (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Assets:    
Derivatives $ 37 $ 72
Cash equivalents 501  
Other investments 10  
Total 3,583  
Liabilities:    
Derivatives 326 267
Contingent consideration 11  
Other 24  
Total 436  
Collateral already posted, assets, aggregate fair value 22  
Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Cash equivalents 486  
Total 1,625  
Liabilities:    
Contingent consideration 0  
Other 0  
Total 9  
Significant Other Observable Inputs (Level 2)    
Assets:    
Cash equivalents 15  
Total 1,736  
Liabilities:    
Contingent consideration 0  
Other 13  
Total 405  
Significant Unobservable Inputs (Level 3)    
Assets:    
Cash equivalents 0  
Other investments 10  
Total 18  
Liabilities:    
Contingent consideration 11  
Other 11  
Total 22  
Net Asset Value as a Practical Expedient (NAV)    
Assets:    
Total 204  
Energy-related derivatives    
Assets:    
Derivatives 78  
Liabilities:    
Derivatives 160  
Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 2  
Liabilities:    
Derivatives 9  
Energy-related derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 76  
Liabilities:    
Derivatives 151  
Energy-related derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
Interest rate derivatives    
Assets:    
Derivatives 7  
Liabilities:    
Derivatives 191  
Interest rate derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
Interest rate derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 7  
Liabilities:    
Derivatives 191  
Interest rate derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
Domestic equity    
Assets:    
Investments in trusts 1,143  
Domestic equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 884  
Domestic equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 259  
Domestic equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Foreign equity    
Assets:    
Investments in trusts 408  
Foreign equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 177  
Foreign equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 231  
Foreign equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
U.S. Treasury and government agency securities    
Assets:    
Investments in trusts 390  
Investments, available-for-sale: 14  
U.S. Treasury and government agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
Investments, available-for-sale: 2  
U.S. Treasury and government agency securities | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 390  
Investments, available-for-sale: 12  
U.S. Treasury and government agency securities | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Investments, available-for-sale: 0  
Municipal bonds    
Assets:    
Investments in trusts 50  
Investments, available-for-sale: 1  
Municipal bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
Investments, available-for-sale: 0  
Municipal bonds | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 50  
Investments, available-for-sale: 1  
Municipal bonds | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Investments, available-for-sale: 0  
Pooled funds – fixed income    
Assets:    
Investments in trusts 4  
Pooled funds – fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
Pooled funds – fixed income | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 4  
Pooled funds – fixed income | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Corporate bonds    
Assets:    
Investments in trusts 529  
Investments, available-for-sale: 3  
Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
Investments, available-for-sale: 0  
Corporate bonds | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 529  
Investments, available-for-sale: 3  
Corporate bonds | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Investments, available-for-sale: 0  
Mortgage- and asset-backed securities    
Assets:    
Investments in trusts 108  
Investments, available-for-sale: 4  
Mortgage- and asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
Investments, available-for-sale: 0  
Mortgage- and asset-backed securities | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 108  
Investments, available-for-sale: 4  
Mortgage- and asset-backed securities | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Investments, available-for-sale: 0  
Private equity    
Assets:    
Investments in trusts 195  
Private equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
Private equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 0  
Private equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Private equity | Net Asset Value as a Practical Expedient (NAV)    
Assets:    
Investments in trusts 195  
Cash and cash equivalents    
Assets:    
Investments in trusts 1  
Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 1  
Cash and cash equivalents | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 0  
Cash and cash equivalents | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Other    
Assets:    
Investments in trusts 75  
Other investments 57  
Other | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 63  
Other investments 10  
Other | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 3  
Other investments 39  
Other | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
Other investments 8  
Other | Net Asset Value as a Practical Expedient (NAV)    
Assets:    
Investments in trusts 9  
Foreign currency derivatives    
Assets:    
Derivatives 5  
Liabilities:    
Derivatives 50  
Foreign currency derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
Foreign currency derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 5  
Liabilities:    
Derivatives 50  
Foreign currency derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
ALABAMA POWER CO    
Assets:    
Derivatives 2 6
Cash equivalents 24  
Other investments 39  
Total 1,596  
Liabilities:    
Derivatives 25 18
Collateral already posted, assets, aggregate fair value 0  
ALABAMA POWER CO | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Cash equivalents 9  
Other investments 0  
Total 701  
ALABAMA POWER CO | Significant Other Observable Inputs (Level 2)    
Assets:    
Cash equivalents 15  
Other investments 39  
Total 691  
ALABAMA POWER CO | Significant Unobservable Inputs (Level 3)    
Assets:    
Cash equivalents 0  
Other investments 0  
Total 0  
ALABAMA POWER CO | Net Asset Value as a Practical Expedient (NAV)    
Assets:    
Total 204  
ALABAMA POWER CO | Energy-related derivatives    
Assets:    
Derivatives 25  
Liabilities:    
Derivatives 48  
ALABAMA POWER CO | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
ALABAMA POWER CO | Energy-related derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 25  
Liabilities:    
Derivatives 48  
ALABAMA POWER CO | Energy-related derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
ALABAMA POWER CO | Domestic equity    
Assets:    
Investments in trusts 750  
ALABAMA POWER CO | Domestic equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 502  
ALABAMA POWER CO | Domestic equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 248  
ALABAMA POWER CO | Domestic equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Foreign equity    
Assets:    
Investments in trusts 177  
ALABAMA POWER CO | Foreign equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 177  
ALABAMA POWER CO | Foreign equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Foreign equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | U.S. Treasury and government agency securities    
Assets:    
Investments in trusts 15  
ALABAMA POWER CO | U.S. Treasury and government agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | U.S. Treasury and government agency securities | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 15  
ALABAMA POWER CO | U.S. Treasury and government agency securities | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Municipal bonds    
Assets:    
Investments in trusts 1  
ALABAMA POWER CO | Municipal bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Municipal bonds | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 1  
ALABAMA POWER CO | Municipal bonds | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Corporate bonds    
Assets:    
Investments in trusts 317  
ALABAMA POWER CO | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Corporate bonds | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 317  
ALABAMA POWER CO | Corporate bonds | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Mortgage- and asset-backed securities    
Assets:    
Investments in trusts 30  
ALABAMA POWER CO | Mortgage- and asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Mortgage- and asset-backed securities | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 30  
ALABAMA POWER CO | Mortgage- and asset-backed securities | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Private equity    
Assets:    
Investments in trusts 195  
ALABAMA POWER CO | Private equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Private equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Private equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Private equity | Net Asset Value as a Practical Expedient (NAV)    
Assets:    
Investments in trusts 195  
ALABAMA POWER CO | Other    
Assets:    
Investments in trusts 23  
ALABAMA POWER CO | Other | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 13  
ALABAMA POWER CO | Other | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 1  
ALABAMA POWER CO | Other | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
ALABAMA POWER CO | Other | Net Asset Value as a Practical Expedient (NAV)    
Assets:    
Investments in trusts 9  
GEORGIA POWER CO    
Assets:    
Derivatives 4 4
Cash equivalents 8  
Total 1,411  
Liabilities:    
Derivatives 28 19
GEORGIA POWER CO | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Cash equivalents 8  
Total 440  
GEORGIA POWER CO | Significant Other Observable Inputs (Level 2)    
Assets:    
Cash equivalents 0  
Total 971  
GEORGIA POWER CO | Significant Unobservable Inputs (Level 3)    
Assets:    
Cash equivalents 0  
Total 0  
GEORGIA POWER CO | Energy-related derivatives    
Assets:    
Derivatives 25  
Liabilities:    
Derivatives 49  
GEORGIA POWER CO | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
GEORGIA POWER CO | Energy-related derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 25  
Liabilities:    
Derivatives 49  
GEORGIA POWER CO | Energy-related derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
GEORGIA POWER CO | Domestic equity    
Assets:    
Investments in trusts 383  
GEORGIA POWER CO | Domestic equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 382  
GEORGIA POWER CO | Domestic equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 1  
GEORGIA POWER CO | Domestic equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Foreign equity    
Assets:    
Investments in trusts 229  
GEORGIA POWER CO | Foreign equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Foreign equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 229  
GEORGIA POWER CO | Foreign equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | U.S. Treasury and government agency securities    
Assets:    
Investments in trusts 375  
GEORGIA POWER CO | U.S. Treasury and government agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | U.S. Treasury and government agency securities | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 375  
GEORGIA POWER CO | U.S. Treasury and government agency securities | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Municipal bonds    
Assets:    
Investments in trusts 49  
GEORGIA POWER CO | Municipal bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Municipal bonds | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 49  
GEORGIA POWER CO | Municipal bonds | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Corporate bonds    
Assets:    
Investments in trusts 212  
GEORGIA POWER CO | Corporate bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Corporate bonds | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 212  
GEORGIA POWER CO | Corporate bonds | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Mortgage- and asset-backed securities    
Assets:    
Investments in trusts 78  
GEORGIA POWER CO | Mortgage- and asset-backed securities | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Mortgage- and asset-backed securities | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 78  
GEORGIA POWER CO | Mortgage- and asset-backed securities | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
GEORGIA POWER CO | Other    
Assets:    
Investments in trusts 52  
GEORGIA POWER CO | Other | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Investments in trusts 50  
GEORGIA POWER CO | Other | Significant Other Observable Inputs (Level 2)    
Assets:    
Investments in trusts 2  
GEORGIA POWER CO | Other | Significant Unobservable Inputs (Level 3)    
Assets:    
Investments in trusts 0  
MISSISSIPPI POWER CO    
Assets:    
Derivatives 1 1
Liabilities:    
Derivatives 20 14
MISSISSIPPI POWER CO | Energy-related derivatives    
Assets:    
Derivatives 19  
Liabilities:    
Derivatives 38  
MISSISSIPPI POWER CO | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
MISSISSIPPI POWER CO | Energy-related derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 19  
Liabilities:    
Derivatives 38  
MISSISSIPPI POWER CO | Energy-related derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
SOUTHERN POWER CO    
Assets:    
Derivatives 8 21
Total 19  
Liabilities:    
Derivatives 2 1
Contingent consideration 11  
Other 24  
Total 38  
Collateral already posted, assets, aggregate fair value 0  
SOUTHERN POWER CO | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Total 0  
Liabilities:    
Contingent consideration 0  
Other 0  
Total 0  
SOUTHERN POWER CO | Significant Other Observable Inputs (Level 2)    
Assets:    
Total 9  
Liabilities:    
Contingent consideration 0  
Other 13  
Total 16  
SOUTHERN POWER CO | Significant Unobservable Inputs (Level 3)    
Assets:    
Total 10  
Liabilities:    
Contingent consideration 11  
Other 11  
Total 22  
SOUTHERN POWER CO | Energy-related derivatives    
Assets:    
Derivatives 4  
Liabilities:    
Derivatives 3  
SOUTHERN POWER CO | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
SOUTHERN POWER CO | Energy-related derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 4  
Liabilities:    
Derivatives 3  
SOUTHERN POWER CO | Energy-related derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
SOUTHERN POWER CO | Other    
Assets:    
Derivatives 10  
SOUTHERN POWER CO | Other | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 0  
SOUTHERN POWER CO | Other | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 0  
SOUTHERN POWER CO | Other | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 10  
SOUTHERN POWER CO | Foreign currency derivatives    
Assets:    
Derivatives 5  
SOUTHERN POWER CO | Foreign currency derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 0  
SOUTHERN POWER CO | Foreign currency derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 5  
SOUTHERN POWER CO | Foreign currency derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
SOUTHERN Co GAS    
Assets:    
Derivatives 15 28
Cash equivalents 121  
Total 143  
Liabilities:    
Derivatives 65 65
Total 77  
Collateral already posted, assets, aggregate fair value 22 $ 33
SOUTHERN Co GAS | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Cash equivalents 121  
Total 124  
Liabilities:    
Total 9  
SOUTHERN Co GAS | Significant Other Observable Inputs (Level 2)    
Assets:    
Cash equivalents 0  
Total 19  
Liabilities:    
Total 68  
SOUTHERN Co GAS | Significant Unobservable Inputs (Level 3)    
Assets:    
Cash equivalents 0  
Total 0  
Liabilities:    
Total 0  
SOUTHERN Co GAS | Energy-related derivatives    
Assets:    
Derivatives 5  
Liabilities:    
Derivatives 22  
SOUTHERN Co GAS | Energy-related derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Derivatives 2  
Liabilities:    
Derivatives 9  
SOUTHERN Co GAS | Energy-related derivatives | Significant Other Observable Inputs (Level 2)    
Assets:    
Derivatives 3  
Liabilities:    
Derivatives 13  
SOUTHERN Co GAS | Energy-related derivatives | Significant Unobservable Inputs (Level 3)    
Assets:    
Derivatives 0  
Liabilities:    
Derivatives 0  
SOUTHERN Co GAS | Interest rate derivatives    
Liabilities:    
Derivatives 55  
SOUTHERN Co GAS | Interest rate derivatives | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Liabilities:    
Derivatives 0  
SOUTHERN Co GAS | Interest rate derivatives | Significant Other Observable Inputs (Level 2)    
Liabilities:    
Derivatives 55  
SOUTHERN Co GAS | Interest rate derivatives | Significant Unobservable Inputs (Level 3)    
Liabilities:    
Derivatives 0  
SOUTHERN Co GAS | Domestic equity    
Assets:    
Non-qualified deferred compensation trusts 10  
SOUTHERN Co GAS | Domestic equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Non-qualified deferred compensation trusts 0  
SOUTHERN Co GAS | Domestic equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Non-qualified deferred compensation trusts 10  
SOUTHERN Co GAS | Domestic equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Non-qualified deferred compensation trusts 0  
SOUTHERN Co GAS | Foreign equity    
Assets:    
Non-qualified deferred compensation trusts 2  
SOUTHERN Co GAS | Foreign equity | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Non-qualified deferred compensation trusts 0  
SOUTHERN Co GAS | Foreign equity | Significant Other Observable Inputs (Level 2)    
Assets:    
Non-qualified deferred compensation trusts 2  
SOUTHERN Co GAS | Foreign equity | Significant Unobservable Inputs (Level 3)    
Assets:    
Non-qualified deferred compensation trusts 0  
SOUTHERN Co GAS | Pooled funds – fixed income    
Assets:    
Non-qualified deferred compensation trusts 4  
SOUTHERN Co GAS | Pooled funds – fixed income | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Non-qualified deferred compensation trusts 0  
SOUTHERN Co GAS | Pooled funds – fixed income | Significant Other Observable Inputs (Level 2)    
Assets:    
Non-qualified deferred compensation trusts 4  
SOUTHERN Co GAS | Pooled funds – fixed income | Significant Unobservable Inputs (Level 3)    
Assets:    
Non-qualified deferred compensation trusts 0  
SOUTHERN Co GAS | Cash and cash equivalents    
Assets:    
Non-qualified deferred compensation trusts 1  
SOUTHERN Co GAS | Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Assets:    
Non-qualified deferred compensation trusts 1  
SOUTHERN Co GAS | Cash and cash equivalents | Significant Other Observable Inputs (Level 2)    
Assets:    
Non-qualified deferred compensation trusts 0  
SOUTHERN Co GAS | Cash and cash equivalents | Significant Unobservable Inputs (Level 3)    
Assets:    
Non-qualified deferred compensation trusts $ 0  
v3.26.1
Fair Value Measurements - Schedule of Increase (Decrease) In Fair Value Of Funds (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Fair Value, Option, Quantitative Disclosures [Line Items]    
Increase (decrease) in fair value of funds $ (44) $ (6)
ALABAMA POWER CO    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Increase (decrease) in fair value of funds (30) (13)
GEORGIA POWER CO    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Increase (decrease) in fair value of funds $ (14) $ 7
v3.26.1
Fair Value Measurements - Narrative (Details) - ALABAMA POWER CO - Private equity
$ in Millions
Mar. 31, 2026
USD ($)
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]  
Fair value $ 204
Unfunded commitments $ 73
v3.26.1
Fair Value Measurements - Schedule of Financial Instruments for which Carrying Amount did not Equal Fair Value (Details)
$ in Billions
Mar. 31, 2026
USD ($)
Long-term debt, including securities due within one year:  
Carrying amount $ 72.1
Fair value 66.5
ALABAMA POWER CO  
Long-term debt, including securities due within one year:  
Carrying amount 12.0
Fair value 10.7
GEORGIA POWER CO  
Long-term debt, including securities due within one year:  
Carrying amount 21.7
Fair value 20.2
MISSISSIPPI POWER CO  
Long-term debt, including securities due within one year:  
Carrying amount 1.8
Fair value 1.7
SOUTHERN POWER CO  
Long-term debt, including securities due within one year:  
Carrying amount 2.9
Fair value 2.8
SOUTHERN Co GAS  
Long-term debt, including securities due within one year:  
Carrying amount 9.3
Fair value $ 8.3
v3.26.1
Derivatives - Schedule of Energy-Related Derivatives (Details) - Energy-related, Natural Gas
MMBTU in Millions
Mar. 31, 2026
MMBTU
Energy-related derivative contracts  
Net Purchased mmBtu 469.0
ALABAMA POWER CO  
Energy-related derivative contracts  
Net Purchased mmBtu 145.0
GEORGIA POWER CO  
Energy-related derivative contracts  
Net Purchased mmBtu 132.0
MISSISSIPPI POWER CO  
Energy-related derivative contracts  
Net Purchased mmBtu 112.0
SOUTHERN POWER CO  
Energy-related derivative contracts  
Net Purchased mmBtu 7.0
SOUTHERN Co GAS  
Energy-related derivative contracts  
Net Purchased mmBtu 73.0
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Long  
Energy-related derivative contracts  
Derivative nonmonetary notional amount net long short position volume 80.0
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Short  
Energy-related derivative contracts  
Derivative nonmonetary notional amount net long short position volume 7.0
v3.26.1
Derivatives - Narrative (Details)
MMBTU in Millions
 3 Months Ended
Mar. 31, 2026
USD ($)
MMBTU
Mar. 31, 2025
USD ($)
Dec. 31, 2025
USD ($)
Derivative [Line Items]      
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU 13.0    
Energy-related derivative hedge gain (loss) to be reclassified within twelve months $ 0    
Gain (Loss) From Derivatives Recognized in OCI (3,000,000) $ 20,000,000  
Collateral already posted, assets, aggregate fair value 22,000,000    
Derivatives 326,000,000   $ 267,000,000
Interest rate derivatives      
Derivative [Line Items]      
Derivatives 26,000,000    
Interest rate derivatives | Cash Flow Hedging      
Derivative [Line Items]      
Gain (Loss) From Derivatives Recognized in OCI 0 (2,000,000)  
Interest rate derivatives | Cash Flow Hedging | Interest Expense      
Derivative [Line Items]      
Gain (loss) on hedges (2,000,000) (2,000,000)  
Interest rate derivatives | Fair Value Hedging | Interest Expense      
Derivative [Line Items]      
Gain (loss) on hedges 20,000,000 40,000,000  
Energy-related derivatives | Cash Flow Hedging      
Derivative [Line Items]      
Gain (Loss) From Derivatives Recognized in OCI 10,000,000 19,000,000  
Foreign currency derivatives | Cash Flow Hedging      
Derivative [Line Items]      
Gain (Loss) From Derivatives Recognized in OCI (12,000,000) 19,000,000  
Foreign currency derivatives | Cash Flow Hedging | Interest Expense      
Derivative [Line Items]      
Gain (loss) on hedges $ (3,000,000) (3,000,000)  
ALABAMA POWER CO      
Derivative [Line Items]      
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU 3.0    
Collateral already posted, assets, aggregate fair value $ 0    
Derivatives 25,000,000   18,000,000
ALABAMA POWER CO | Interest rate derivatives      
Derivative [Line Items]      
Cash flow hedge gain (loss) to be reclassified within twelve months $ 0    
GEORGIA POWER CO      
Derivative [Line Items]      
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU 5.0    
Derivatives $ 28,000,000   19,000,000
GEORGIA POWER CO | Interest rate derivatives      
Derivative [Line Items]      
Cash flow hedge gain (loss) to be reclassified within twelve months 0    
GEORGIA POWER CO | Interest rate derivatives | Cash Flow Hedging      
Derivative [Line Items]      
Gain (Loss) From Derivatives Recognized in OCI $ 0 (2,000,000)  
MISSISSIPPI POWER CO      
Derivative [Line Items]      
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU 2.0    
Derivatives $ 20,000,000   14,000,000
MISSISSIPPI POWER CO | Interest rate derivatives      
Derivative [Line Items]      
Cash flow hedge gain (loss) to be reclassified within twelve months $ 0    
SOUTHERN POWER CO      
Derivative [Line Items]      
Expected volume of natural gas subject to option to sell back excess gas due to operational constraints | MMBTU 3.0    
Energy-related derivative hedge gain (loss) to be reclassified within twelve months $ 0    
Foreign currency cash flow hedge gain (loss) to be reclassified during next 12 months 0    
Gain (Loss) From Derivatives Recognized in OCI (10,000,000) 22,000,000  
Collateral already posted, assets, aggregate fair value 0    
Derivatives 2,000,000   1,000,000
SOUTHERN POWER CO | Interest rate derivatives      
Derivative [Line Items]      
Cash flow hedge gain (loss) to be reclassified within twelve months 0    
Derivatives 0    
SOUTHERN POWER CO | Energy-related derivatives      
Derivative [Line Items]      
Derivatives 0    
SOUTHERN POWER CO | Energy-related derivatives | Cash Flow Hedging      
Derivative [Line Items]      
Gain (Loss) From Derivatives Recognized in OCI 2,000,000 3,000,000  
SOUTHERN POWER CO | Foreign currency derivatives | Cash Flow Hedging      
Derivative [Line Items]      
Gain (Loss) From Derivatives Recognized in OCI (12,000,000) 19,000,000  
SOUTHERN POWER CO | Foreign currency derivatives | Cash Flow Hedging | Interest Expense      
Derivative [Line Items]      
Gain (loss) on hedges (3,000,000) (3,000,000)  
Registrants | Derivative Counterparties      
Derivative [Line Items]      
Collateral already posted, assets, aggregate fair value 0    
SOUTHERN Co GAS      
Derivative [Line Items]      
Energy-related derivative hedge gain (loss) to be reclassified within twelve months 0    
Collateral already posted, assets, aggregate fair value 22,000,000   33,000,000
Derivatives 65,000,000   $ 65,000,000
SOUTHERN Co GAS | Interest rate derivatives      
Derivative [Line Items]      
Cash flow hedge gain (loss) to be reclassified within twelve months 0    
SOUTHERN Co GAS | Interest rate derivatives | Fair Value Hedging | Interest Expense      
Derivative [Line Items]      
Gain (loss) on hedges 29,000,000 17,000,000  
SOUTHERN Co GAS | Energy-related derivatives | Cash Flow Hedging      
Derivative [Line Items]      
Gain (Loss) From Derivatives Recognized in OCI 8,000,000 $ 16,000,000  
Traditional Electric Operating Companies | Energy-related derivatives      
Derivative [Line Items]      
Derivatives $ 0    
v3.26.1
Derivatives - Schedule of Interest Rate Derivatives (Details) - Interest rate derivatives
$ in Millions
 3 Months Ended
Mar. 31, 2026
USD ($)
Derivative [Line Items]  
Notional Amount $ 2,465
Fair Value Gain (Loss) (184)
Southern Company parent | Fair Value Hedges of Existing Debt | Date One  
Derivative [Line Items]  
Notional Amount $ 400
Weighted Average Interest Rate Paid 0.80%
Interest Rate Received 1.75%
Fair Value Gain (Loss) $ (20)
Southern Company parent | Fair Value Hedges of Existing Debt | Date Two  
Derivative [Line Items]  
Notional Amount $ 1,000
Weighted Average Interest Rate Paid 2.48%
Interest Rate Received 3.70%
Fair Value Gain (Loss) $ (103)
Southern Company parent | Fair Value Hedges of Existing Debt | Date Three  
Derivative [Line Items]  
Notional Amount $ 565
Weighted Average Interest Rate Paid 1.56%
Interest Rate Received 6.50%
Fair Value Gain (Loss) $ (6)
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt  
Derivative [Line Items]  
Fair Value Gain (Loss) (55)
SOUTHERN Co GAS | Fair Value Hedges of Existing Debt | Date One  
Derivative [Line Items]  
Notional Amount $ 500
Weighted Average Interest Rate Paid 0.49%
Interest Rate Received 1.75%
v3.26.1
Derivatives - Schedule of Foreign Currency Derivatives (Details) - 3 months ended Mar. 31, 2026 - Foreign currency derivatives
€ in Millions, $ in Millions
USD ($)
EUR (€)
Derivative [Line Items]    
Pay Notional $ 2,040  
Receive Notional | €   € 1,750
Fair Value Gain (Loss) (45)  
Cash Flow Hedges of Forecasted Debt | SOUTHERN POWER CO    
Derivative [Line Items]    
Pay Notional $ 564  
Pay Rate 3.78%  
Receive Notional | €   500
Receive Rate 1.85%  
Fair Value Gain (Loss) $ 5  
Fair Value Hedges of Existing Debt | Southern Company parent    
Derivative [Line Items]    
Pay Notional $ 1,476  
Pay Rate 3.39%  
Receive Notional | €   € 1,250
Receive Rate 1.88%  
Fair Value Gain (Loss) $ (50)  
v3.26.1
Derivatives - Schedule of Derivative Category and Balance Sheet Location (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized $ 90 $ 93
Gross amounts offset (53) (21)
Derivative asset, net amounts recognized in the balance sheets 37 72
Derivative liability, gross amount recognized 401 321
Gross amounts offset (75) (54)
Derivative liability, net amounts recognized in the balance sheets 326 267
Collateral already posted, assets, aggregate fair value 22  
Interest rate derivatives    
Derivatives, Fair Value [Line Items]    
Derivative liability, net amounts recognized in the balance sheets 26  
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Assets from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 5 6
Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Liabilities from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 5 6
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 69 55
Derivative liability, gross amount recognized 147 99
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Assets from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 35 24
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Liabilities from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 91 64
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 34 31
Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 56 35
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 16 32
Derivative liability, gross amount recognized 249 216
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Assets from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 2 1
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Liabilities from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 8 6
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 2 2
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 0 1
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Assets from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 7 8
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Liabilities from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 49 48
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 0 0
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 142 139
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Assets from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 5 17
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Liabilities from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 22 22
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 0 4
Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 28 0
ALABAMA POWER CO    
Derivatives, Fair Value [Line Items]    
Gross amounts offset (23) (13)
Derivative asset, net amounts recognized in the balance sheets 2 6
Gross amounts offset (23) (13)
Derivative liability, net amounts recognized in the balance sheets 25 18
Collateral already posted, assets, aggregate fair value 0  
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 25 19
Derivative liability, gross amount recognized 48 31
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 12 9
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 26 18
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 13 10
ALABAMA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 22 13
GEORGIA POWER CO    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 25 18
Gross amounts offset (21) (14)
Derivative asset, net amounts recognized in the balance sheets 4 4
Derivative liability, gross amount recognized 49 33
Gross amounts offset (21) (14)
Derivative liability, net amounts recognized in the balance sheets 28 19
GEORGIA POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 3 1
GEORGIA POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 0 0
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 22 17
Derivative liability, gross amount recognized 49 33
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Assets from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 13 7
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 32 23
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 9 10
GEORGIA POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 17 10
MISSISSIPPI POWER CO    
Derivatives, Fair Value [Line Items]    
Gross amounts offset (18) (13)
Derivative asset, net amounts recognized in the balance sheets 1 1
Gross amounts offset (18) (13)
Derivative liability, net amounts recognized in the balance sheets 20 14
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 19 14
Derivative liability, gross amount recognized 38 27
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Assets from risk management activities    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 7 3
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 21 15
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 12 11
MISSISSIPPI POWER CO | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 17 12
SOUTHERN POWER CO    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 9 21
Gross amounts offset (1) 0
Derivative asset, net amounts recognized in the balance sheets 8 21
Derivative liability, gross amount recognized 3 1
Gross amounts offset (1) 0
Derivative liability, net amounts recognized in the balance sheets 2 1
Collateral already posted, assets, aggregate fair value 0  
SOUTHERN POWER CO | Energy-related derivatives    
Derivatives, Fair Value [Line Items]    
Derivative liability, net amounts recognized in the balance sheets 0  
SOUTHERN POWER CO | Interest rate derivatives    
Derivatives, Fair Value [Line Items]    
Derivative liability, net amounts recognized in the balance sheets 0  
SOUTHERN POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 1 1
SOUTHERN POWER CO | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 1 0
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 8 20
Derivative liability, gross amount recognized 2 1
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 1 1
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 2 1
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 2 2
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 0 0
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 5 17
SOUTHERN POWER CO | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Foreign currency derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 0 0
SOUTHERN Co GAS    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 5 9
Gross amounts offset 10 19
Derivative asset, net amounts recognized in the balance sheets 15 28
Derivative liability, gross amount recognized 77 79
Gross amounts offset (12) (14)
Derivative liability, net amounts recognized in the balance sheets 65 65
Collateral already posted, assets, aggregate fair value 22 33
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 1 4
SOUTHERN Co GAS | Energy-related derivatives not designated as hedging instruments | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 4 6
SOUTHERN Co GAS | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 3 5
SOUTHERN Co GAS | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 12 8
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 1 0
Derivative liability, gross amount recognized 61 65
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 1 0
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 6 5
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 0 0
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Energy-related derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 0 1
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other current assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 0 0
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other current liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized 12 13
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other deferred charges and assets    
Derivatives, Fair Value [Line Items]    
Derivative asset, gross amount recognized 0 0
SOUTHERN Co GAS | Derivatives designated as hedging instruments in cash flow and fair value hedges | Energy-related derivatives designated as hedging instruments for regulatory purposes | Interest rate derivatives | Other deferred credits and liabilities    
Derivatives, Fair Value [Line Items]    
Derivative liability, gross amount recognized $ 43 $ 46
v3.26.1
Derivatives - Schedule of Pre-tax Effects of Unrealized Derivative Gains (Losses) (Details) - Energy-related derivatives - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) $ (78) $ (45)
Other regulatory assets, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (60) (48)
Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (23) (8)
Other regulatory liabilities, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 4 7
Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 1 4
ALABAMA POWER CO    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (23) (12)
ALABAMA POWER CO | Other regulatory assets, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (16) (13)
ALABAMA POWER CO | Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (10) (5)
ALABAMA POWER CO | Other regulatory liabilities, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 2 4
ALABAMA POWER CO | Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 1 2
GEORGIA POWER CO    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (27) (16)
GEORGIA POWER CO | Other regulatory assets, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (20) (17)
GEORGIA POWER CO | Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (8) (1)
GEORGIA POWER CO | Other regulatory liabilities, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 1 1
GEORGIA POWER CO | Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 0 1
MISSISSIPPI POWER CO    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (19) (13)
MISSISSIPPI POWER CO | Other regulatory assets, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (14) (12)
MISSISSIPPI POWER CO | Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (5) (2)
MISSISSIPPI POWER CO | Other regulatory liabilities, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 0 0
MISSISSIPPI POWER CO | Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 0 1
SOUTHERN Co GAS    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (9) (4)
SOUTHERN Co GAS | Other regulatory assets, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) (10) (6)
SOUTHERN Co GAS | Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 0 0
SOUTHERN Co GAS | Other regulatory liabilities, current    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) 1 2
SOUTHERN Co GAS | Other regulatory assets, deferred    
Derivative Instruments, Gain (Loss) [Line Items]    
Total energy-related derivative gains (losses) $ 0 $ 0
v3.26.1
Derivatives - Schedule of Pre-Tax Effects of Hedging on AOCI (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI $ (3) $ 20
Cash Flow Hedging | Energy-related derivatives    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI 10 19
Cash Flow Hedging | Interest rate derivatives    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI 0 (2)
Cash Flow Hedging | Foreign currency derivatives    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI (12) 19
Fair Value Hedging | Foreign currency derivatives    
Derivative Instruments, Gain (Loss) [Line Items]    
Amount excluded from effectiveness testing recognized in earnings (1) (16)
GEORGIA POWER CO | Cash Flow Hedging | Interest rate derivatives    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI 0 (2)
SOUTHERN POWER CO    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI (10) 22
SOUTHERN POWER CO | Cash Flow Hedging | Energy-related derivatives    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI 2 3
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI (12) 19
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives    
Derivative Instruments, Gain (Loss) [Line Items]    
Gain (Loss) From Derivatives Recognized in OCI $ 8 $ 16
v3.26.1
Derivatives - Schedule of Pre-Tax Effects of Cash Flow and Fair Value Hedging on Income (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Other Income (Expense)    
Derivative [Line Items]    
Amount excluded from effectiveness testing recognized in earnings $ 1 $ 16
Cash Flow Hedging | Energy-related derivatives | Cost of Goods and Services Sold | Fuel    
Derivative [Line Items]    
Gain (loss) on hedges 3 1
Cash Flow Hedging | Energy-related derivatives | Cost of Goods and Services Sold | Natural gas    
Derivative [Line Items]    
Gain (loss) on hedges 10 (1)
Cash Flow Hedging | Interest rate derivatives | Interest Expense    
Derivative [Line Items]    
Gain (loss) on hedges (2) (2)
Cash Flow Hedging | Foreign currency derivatives | Interest Expense    
Derivative [Line Items]    
Gain (loss) on hedges (3) (3)
Cash Flow Hedging | Foreign currency derivatives | Other Income (Expense)    
Derivative [Line Items]    
Gain (loss) on hedges (13) 21
Fair Value Hedging | Interest rate derivatives | Interest Expense    
Derivative [Line Items]    
Gain (loss) on hedges 20 40
Fair Value Hedging | Foreign currency derivatives    
Derivative [Line Items]    
Amount excluded from effectiveness testing recognized in earnings (1) (16)
Fair Value Hedging | Foreign currency derivatives | Other Income (Expense)    
Derivative [Line Items]    
Gain (loss) on hedges (32) 40
SOUTHERN POWER CO | Cash Flow Hedging | Energy-related derivatives | Cost of Goods and Services Sold | Fuel    
Derivative [Line Items]    
Gain (loss) on hedges 3 1
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives | Interest Expense    
Derivative [Line Items]    
Gain (loss) on hedges (3) (3)
SOUTHERN POWER CO | Cash Flow Hedging | Foreign currency derivatives | Other Income (Expense)    
Derivative [Line Items]    
Gain (loss) on hedges (13) 21
SOUTHERN Co GAS | Cash Flow Hedging | Energy-related derivatives | Cost of Sales | Natural gas    
Derivative [Line Items]    
Gain (loss) on hedges 10 (1)
SOUTHERN Co GAS | Fair Value Hedging | Interest rate derivatives | Interest Expense    
Derivative [Line Items]    
Gain (loss) on hedges $ 29 $ 17
v3.26.1
Derivatives - Schedule of Cumulative Basis Adjustments for Fair Value Hedges (Details) - Fair Value Hedging - Long-term debt - USD ($)
$ in Millions
Mar. 31, 2026
Dec. 31, 2025
Derivative [Line Items]    
Carrying Amount of the Hedged Item $ (3,710) $ (3,742)
Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item 158 156
SOUTHERN Co GAS    
Derivative [Line Items]    
Carrying Amount of the Hedged Item (446) (446)
Cumulative Amount of Fair Value Hedging Adjustment included in Carrying Amount of the Hedged Item $ 52 $ 51
v3.26.1
Acquisitions and Dispositions - Narrative (Details) - SOUTHERN POWER CO
$ in Millions
 3 Months Ended
Mar. 31, 2026
USD ($)
MW
Millers Branch Solar Development Phase 2  
Business Combination [Line Items]  
Approximate nameplate capacity | MW 180
Millers Branch Solar Development Phase 3  
Business Combination [Line Items]  
Approximate nameplate capacity | MW 132
Millers Branch Solar Development  
Business Combination [Line Items]  
Construction costs incurred to date $ 692
Construction work in progress 387
Wind Facilities  
Business Combination [Line Items]  
Construction work in progress 432
Franklin And Wansley Natural Gas Facilities  
Business Combination [Line Items]  
Construction work in progress $ 0
Franklin And Wansley Natural Gas Facilities | Maximum  
Business Combination [Line Items]  
Additional capacity | MW 400
v3.26.1
Acquisitions and Dispositions - Schedule of Construction Projects (Details) - SOUTHERN POWER CO - MW
 3 Months Ended
Mar. 31, 2026
Feb. 28, 2026
Millers Branch Solar Development Phase 1    
Business Combination [Line Items]    
Life output of plant (in years) 20 years  
Nameplate capacity placed in service   200
Millers Branch Solar Development Phase 2    
Business Combination [Line Items]    
Approximate nameplate capacity 180  
Life output of plant (in years) 15 years  
Millers Branch Solar Development Phase 3    
Business Combination [Line Items]    
Approximate nameplate capacity 132  
Life output of plant (in years) 15 years  
v3.26.1
Acquisitions and Dispositions - Schedule of Wind Repowering Projects (Details) - SOUTHERN POWER CO - MW
Apr. 29, 2026
Mar. 31, 2026
Kay Wind    
Business Combination [Line Items]    
Approximate nameplate capacity   200
Kay Wind | Subsequent Event    
Business Combination [Line Items]    
Nameplate capacity placed in service 51  
Kay Wind | Maximum    
Business Combination [Line Items]    
Approximate nameplate capacity   299
Grant    
Business Combination [Line Items]    
Approximate nameplate capacity   152
Grant Plains    
Business Combination [Line Items]    
Approximate nameplate capacity   147
Wake    
Business Combination [Line Items]    
Approximate nameplate capacity   257
Bethel Wind Facility    
Business Combination [Line Items]    
Approximate nameplate capacity   276
v3.26.1
Segment and Related Information - Narrative (Details)
$ in Millions
 3 Months Ended
Mar. 31, 2026
USD ($)
state
segment
Mar. 31, 2025
USD ($)
Segment Reporting Information [Line Items]    
Number of states in which entity operates | state 3  
Operating revenues $ 8,040 $ 7,591
Earnings from equity method investments 50 32
Other segment items $ 4,665 4,193
Traditional Electric Operating Companies    
Segment Reporting Information [Line Items]    
Number of operating segments | segment 3  
Number of reportable segments | segment 1  
SOUTHERN POWER CO    
Segment Reporting Information [Line Items]    
Number of reportable segments | segment 1  
Operating revenues $ 523 432
Earnings from equity method investments 0 0
SOUTHERN POWER CO | Kay Wind Facility    
Segment Reporting Information [Line Items]    
Depreciation before tax 154 27
Depreciation after tax 120 20
SOUTHERN POWER CO | Reportable Segment    
Segment Reporting Information [Line Items]    
Other segment items $ 442 303
SOUTHERN Co GAS    
Segment Reporting Information [Line Items]    
Number of states in which entity operates | state 4  
Number of reportable segments | segment 3  
Operating revenues $ 2,174 1,840
Earnings from equity method investments 46 39
Other segment items $ 1,357 1,069
SOUTHERN Co GAS | Southern Natural Gas Company, LLC    
Segment Reporting Information [Line Items]    
Ownership percentage, equity method investment 50.00%  
SOUTHERN Co GAS | Dalton Pipeline    
Segment Reporting Information [Line Items]    
Ownership percentage, equity method investment 50.00%  
MISSISSIPPI POWER CO    
Segment Reporting Information [Line Items]    
Operating revenues $ 464 406
MISSISSIPPI POWER CO | Reportable Segment    
Segment Reporting Information [Line Items]    
Other segment items 251 218
Traditional Electric Operating Companies | Wholesale revenues, affiliates | SOUTHERN POWER CO    
Segment Reporting Information [Line Items]    
Operating revenues $ 100 $ 116
v3.26.1
Segment and Related Information - Schedule of Financial Data for Business Segments (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Segment Reporting Information [Line Items]      
Operating revenues $ 8,397 $ 7,775  
Other segment items 4,665 4,193  
Depreciation and amortization(b) 1,420 1,286  
Earnings from equity method investments 50 32  
Interest expense(c) 778 714  
Income taxes (benefit) 228 280  
Consolidated Net Income Attributable to Southern Company 1,356 1,334  
Goodwill 5,161   $ 5,161
Total assets 157,031   155,720
Loss from extinguishment of debt 11    
Loss from extinguishment of debt, net of tax 8    
SOUTHERN POWER CO      
Segment Reporting Information [Line Items]      
Operating revenues 681 567  
Depreciation and amortization(b) 278 152  
Earnings from equity method investments 0 0  
Interest expense(c) 27 26  
Income taxes (benefit) (70) (1)  
Consolidated Net Income Attributable to Southern Company 4 87  
Total assets 12,474   12,657
SOUTHERN POWER CO | Kay Wind Facility      
Segment Reporting Information [Line Items]      
Depreciation before tax 154 27  
Depreciation after tax 120 20  
SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Operating revenues 2,191 1,839  
Other segment items 1,357 1,069  
Depreciation and amortization(b) 183 169  
Earnings from equity method investments 46 39  
Interest expense(c) 105 92  
Income taxes (benefit) 145 130  
Consolidated Net Income Attributable to Southern Company 447 418  
Goodwill 5,015   5,015
Total assets 27,551   27,387
GEORGIA POWER CO      
Segment Reporting Information [Line Items]      
Operating revenues 3,142 3,037  
Depreciation and amortization(b) 484 503  
Interest expense(c) 204 187  
Income taxes (benefit) 85 98  
Consolidated Net Income Attributable to Southern Company 628 596  
Total assets 69,720   68,077
ALABAMA POWER CO      
Segment Reporting Information [Line Items]      
Operating revenues 2,092 2,012  
Depreciation and amortization(b) 381 370  
Interest expense(c) 115 108  
Income taxes (benefit) 129 111  
Consolidated Net Income Attributable to Southern Company 425 375  
Total assets 38,151   38,124
Operating Segments      
Segment Reporting Information [Line Items]      
Operating revenues 8,213 7,594  
Other segment items 4,515 4,043  
Depreciation and amortization(b) 1,403 1,268  
Earnings from equity method investments 45 37  
Interest expense(c) 471 434  
Income taxes (benefit) 305 355  
Consolidated Net Income Attributable to Southern Company 1,564 1,531  
Goodwill 5,017   5,017
Total assets 155,141   153,416
Operating Segments | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Operating revenues 2,193 1,839  
Other segment items 1,360 1,072  
Depreciation and amortization(b) 182 168  
Earnings from equity method investments 46 39  
Interest expense(c) 101 92  
Income taxes (benefit) 155 139  
Consolidated Net Income Attributable to Southern Company 441 407  
Total assets 29,396   28,615
Operating Segments | Electric Utilities      
Segment Reporting Information [Line Items]      
Operating revenues 6,022 5,755  
Other segment items 3,158 2,974  
Depreciation and amortization(b) 1,220 1,099  
Earnings from equity method investments (1) (2)  
Interest expense(c) 366 342  
Income taxes (benefit) 160 225  
Consolidated Net Income Attributable to Southern Company 1,117 1,113  
Goodwill 2   2
Total assets 127,590   126,029
Operating Segments | Traditional Electric Operating Companies      
Segment Reporting Information [Line Items]      
Operating revenues 5,482 5,311  
Other segment items 2,857 2,794  
Depreciation and amortization(b) 942 947  
Earnings from equity method investments (1) (2)  
Interest expense(c) 339 316  
Income taxes (benefit) 230 226  
Consolidated Net Income Attributable to Southern Company 1,113 1,026  
Goodwill 0   0
Total assets 115,965   114,287
Operating Segments | SOUTHERN POWER CO      
Segment Reporting Information [Line Items]      
Operating revenues 681 567  
Other segment items 442 303  
Depreciation and amortization(b) 278 152  
Earnings from equity method investments 0 0  
Interest expense(c) 27 26  
Income taxes (benefit) (70) (1)  
Consolidated Net Income Attributable to Southern Company 4 87  
Goodwill 2   2
Total assets 12,474   12,657
Operating Segments | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Operating revenues 2,191 1,839  
Other segment items 1,357 1,069  
Depreciation and amortization(b) 183 169  
Earnings from equity method investments 46 39  
Interest expense(c) 105 92  
Income taxes (benefit) 145 130  
Consolidated Net Income Attributable to Southern Company 447 418  
Goodwill 5,015   5,015
Total assets 27,551   27,387
Eliminations      
Segment Reporting Information [Line Items]      
Operating revenues (34) (48)  
Other segment items (40) (58)  
Depreciation and amortization(b) 0 0  
Earnings from equity method investments 0 (1)  
Interest expense(c) 0 0  
Income taxes (benefit) 0 0  
Consolidated Net Income Attributable to Southern Company 6 9  
Goodwill 0   0
Total assets (794)   (525)
Eliminations | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Operating revenues (4) (4)  
Other segment items (4) (4)  
Depreciation and amortization(b) 0 0  
Earnings from equity method investments 0 0  
Interest expense(c) 0 0  
Income taxes (benefit) 0 0  
Consolidated Net Income Attributable to Southern Company 0 0  
Total assets (13,121)   (11,871)
Eliminations | Electric Utilities      
Segment Reporting Information [Line Items]      
Operating revenues (141) (123)  
Other segment items (141) (123)  
Depreciation and amortization(b) 0 0  
Earnings from equity method investments 0 0  
Interest expense(c) 0 0  
Income taxes (benefit) 0 0  
Consolidated Net Income Attributable to Southern Company 0 0  
Goodwill 0   0
Total assets (849)   (915)
All Other      
Segment Reporting Information [Line Items]      
Operating revenues 218 229  
Other segment items 190 208  
Depreciation and amortization(b) 17 18  
Earnings from equity method investments 5 (4)  
Interest expense(c) 307 280  
Income taxes (benefit) (77) (75)  
Consolidated Net Income Attributable to Southern Company (214) (206)  
Goodwill 144   144
Total assets 2,684   2,829
All Other | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Operating revenues 2 4  
Other segment items 1 1  
Depreciation and amortization(b) 1 1  
Earnings from equity method investments 0 0  
Interest expense(c) 4 0  
Income taxes (benefit) (10) (9)  
Consolidated Net Income Attributable to Southern Company 6 $ 11  
Total assets $ 11,276   $ 10,643
v3.26.1
Segment and Related Information - Schedule of Traditional Electric Companies (Details)
$ in Millions
 3 Months Ended
Mar. 31, 2026
USD ($)
segment
Mar. 31, 2025
USD ($)
Segment Reporting Information [Line Items]    
Total operating revenues $ 8,397 $ 7,775
Utility operations and maintenance    
Total utility operations and maintenance 1,653 1,619
Other segment items 4,665 4,193
Depreciation and amortization(b) 1,420 1,286
Interest expense(c) 778 714
Income taxes (benefit) 228 280
Consolidated Net Income Attributable to Southern Company $ 1,356 1,334
Traditional Electric Operating Companies    
Utility operations and maintenance    
Number of reportable segments | segment 1  
ALABAMA POWER CO    
Segment Reporting Information [Line Items]    
Total operating revenues $ 2,092 2,012
Utility operations and maintenance    
Total utility operations and maintenance 393 463
Depreciation and amortization(b) 381 370
Interest expense(c) 115 108
Income taxes (benefit) 129 111
Consolidated Net Income Attributable to Southern Company 425 375
GEORGIA POWER CO    
Segment Reporting Information [Line Items]    
Total operating revenues 3,142 3,037
Utility operations and maintenance    
Total utility operations and maintenance 672 634
Depreciation and amortization(b) 484 503
Interest expense(c) 204 187
Income taxes (benefit) 85 98
Consolidated Net Income Attributable to Southern Company 628 596
MISSISSIPPI POWER CO    
Segment Reporting Information [Line Items]    
Total operating revenues 472 420
Utility operations and maintenance    
Total utility operations and maintenance 88 84
Depreciation and amortization(b) 55 52
Interest expense(c) 20 20
Income taxes (benefit) 18 16
Consolidated Net Income Attributable to Southern Company 60 55
SOUTHERN POWER CO    
Segment Reporting Information [Line Items]    
Total operating revenues 681 567
Utility operations and maintenance    
Total utility operations and maintenance 137 123
Depreciation and amortization(b) 278 152
Interest expense(c) 27 26
Income taxes (benefit) (70) (1)
Consolidated Net Income Attributable to Southern Company $ 4 87
Number of reportable segments | segment 1  
Reportable Segment | ALABAMA POWER CO    
Segment Reporting Information [Line Items]    
Total operating revenues $ 2,092 2,012
Utility operations and maintenance    
Rate RSE expenses 301 365
Rate CNP Compliance expenses 74 75
Total utility operations and maintenance 375 440
Other segment items 667 608
Depreciation and amortization(b) 381 370
Interest expense(c) 115 108
Income taxes (benefit) 129 111
Consolidated Net Income Attributable to Southern Company 425 375
Capital expenditures 519 560
Reportable Segment | GEORGIA POWER CO    
Segment Reporting Information [Line Items]    
Total operating revenues 3,142 3,037
Utility operations and maintenance    
Total utility operations and maintenance 578 536
Other segment items 1,163 1,117
Depreciation and amortization(b) 484 503
Interest expense(c) 204 187
Income taxes (benefit) 85 98
Consolidated Net Income Attributable to Southern Company 628 596
Capital expenditures 2,070 1,637
Reportable Segment | MISSISSIPPI POWER CO    
Segment Reporting Information [Line Items]    
Total operating revenues 472 420
Operational expenses 64 57
Environmental compliance expenses 4 2
Utility operations and maintenance    
Other segment items 251 218
Depreciation and amortization(b) 55 52
Interest expense(c) 20 20
Income taxes (benefit) 18 16
Consolidated Net Income Attributable to Southern Company 60 55
Capital expenditures 82 73
Reportable Segment | SOUTHERN POWER CO    
Segment Reporting Information [Line Items]    
Total operating revenues 681 567
Utility operations and maintenance    
Other segment items 442 303
Depreciation and amortization(b) 278 152
Interest expense(c) 27 26
Income taxes (benefit) (70) (1)
Consolidated Net Income Attributable to Southern Company $ 4 $ 87
Traditional Electric Operating Companies    
Utility operations and maintenance    
Number of reportable segments | segment 1  
v3.26.1
Segment and Related Information - Schedule of Southern Power (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Segment Reporting Information [Line Items]    
Operating revenues $ 8,397 $ 7,775
Other segment items 4,665 4,193
Depreciation and amortization(b) 1,420 1,286
Earnings from equity method investments 50 32
Interest expense 778 714
Income taxes (benefit) 228 280
Net income 1,356 1,334
Loss from extinguishment of debt 11  
Loss from extinguishment of debt, net of tax 8  
Operating Segments    
Segment Reporting Information [Line Items]    
Operating revenues 8,213 7,594
Other segment items 4,515 4,043
Depreciation and amortization(b) 1,403 1,268
Earnings from equity method investments 45 37
Interest expense 471 434
Income taxes (benefit) 305 355
Net income 1,564 1,531
Eliminations    
Segment Reporting Information [Line Items]    
Operating revenues (34) (48)
Other segment items (40) (58)
Depreciation and amortization(b) 0 0
Earnings from equity method investments 0 (1)
Interest expense 0 0
Income taxes (benefit) 0 0
Net income 6 9
All Other    
Segment Reporting Information [Line Items]    
Operating revenues 218 229
Other segment items 190 208
Depreciation and amortization(b) 17 18
Earnings from equity method investments 5 (4)
Interest expense 307 280
Income taxes (benefit) (77) (75)
Net income (214) (206)
SOUTHERN POWER CO    
Segment Reporting Information [Line Items]    
Operating revenues 681 567
Depreciation and amortization(b) 278 152
Earnings from equity method investments 0 0
Interest expense 27 26
Income taxes (benefit) (70) (1)
Net income 4 87
SOUTHERN POWER CO | Kay Wind Facility    
Segment Reporting Information [Line Items]    
Depreciation before tax 154 27
Depreciation after tax 120 20
Reportable Segment | SOUTHERN POWER CO    
Segment Reporting Information [Line Items]    
Operating revenues 681 567
Other segment items 442 303
Depreciation and amortization(b) 278 152
Interest expense 27 26
Income taxes (benefit) (70) (1)
Net income 4 87
Traditional Electric Operating Companies | Operating Segments    
Segment Reporting Information [Line Items]    
Operating revenues 5,482 5,311
Other segment items 2,857 2,794
Depreciation and amortization(b) 942 947
Earnings from equity method investments (1) (2)
Interest expense 339 316
Income taxes (benefit) 230 226
Net income 1,113 1,026
SOUTHERN POWER CO | Operating Segments    
Segment Reporting Information [Line Items]    
Operating revenues 681 567
Other segment items 442 303
Depreciation and amortization(b) 278 152
Earnings from equity method investments 0 0
Interest expense 27 26
Income taxes (benefit) (70) (1)
Net income 4 87
Electric Utilities | Operating Segments    
Segment Reporting Information [Line Items]    
Operating revenues 6,022 5,755
Other segment items 3,158 2,974
Depreciation and amortization(b) 1,220 1,099
Earnings from equity method investments (1) (2)
Interest expense 366 342
Income taxes (benefit) 160 225
Net income 1,117 1,113
Electric Utilities | Eliminations    
Segment Reporting Information [Line Items]    
Operating revenues (141) (123)
Other segment items (141) (123)
Depreciation and amortization(b) 0 0
Earnings from equity method investments 0 0
Interest expense 0 0
Income taxes (benefit) 0 0
Net income 0 0
SOUTHERN Co GAS | Operating Segments    
Segment Reporting Information [Line Items]    
Operating revenues 2,191 1,839
Other segment items 1,357 1,069
Depreciation and amortization(b) 183 169
Earnings from equity method investments 46 39
Interest expense 105 92
Income taxes (benefit) 145 130
Net income $ 447 $ 418
v3.26.1
Segment and Related Information - Schedule of Gas Revenues (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Dec. 31, 2025
Segment Reporting Information [Line Items]      
Total operating revenues $ 8,397 $ 7,775  
Other segment items 4,665 4,193  
Depreciation and amortization(b) 1,420 1,286  
Earnings from equity method investments 50 32  
Interest expense(c) 778 714  
Income taxes (benefit) 228 280  
Consolidated Net Income Attributable to Southern Company 1,356 1,334  
Total assets 157,031   $ 155,720
SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Total operating revenues 2,191 1,839  
Other segment items 1,357 1,069  
Depreciation and amortization(b) 183 169  
Earnings from equity method investments 46 39  
Interest expense(c) 105 92  
Income taxes (benefit) 145 130  
Consolidated Net Income Attributable to Southern Company 447 418  
Total assets 27,551   27,387
Operating Segments      
Segment Reporting Information [Line Items]      
Total operating revenues 8,213 7,594  
Other segment items 4,515 4,043  
Depreciation and amortization(b) 1,403 1,268  
Earnings from equity method investments 45 37  
Interest expense(c) 471 434  
Income taxes (benefit) 305 355  
Consolidated Net Income Attributable to Southern Company 1,564 1,531  
Total assets 155,141   153,416
Operating Segments | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Total operating revenues 2,193 1,839  
Other segment items 1,360 1,072  
Depreciation and amortization(b) 182 168  
Earnings from equity method investments 46 39  
Interest expense(c) 101 92  
Income taxes (benefit) 155 139  
Consolidated Net Income Attributable to Southern Company 441 407  
Total assets 29,396   28,615
Operating Segments | Gas distribution operations | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Total operating revenues 1,900 1,570  
Other segment items 1,177 905  
Depreciation and amortization(b) 179 164  
Earnings from equity method investments 0 0  
Interest expense(c) 91 82  
Income taxes (benefit) 116 104  
Consolidated Net Income Attributable to Southern Company 337 315  
Total assets 26,111   25,391
Operating Segments | Gas Pipeline Investments | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Total operating revenues 8 8  
Other segment items 0 1  
Depreciation and amortization(b) 1 1  
Earnings from equity method investments 46 39  
Interest expense(c) 9 9  
Income taxes (benefit) 11 9  
Consolidated Net Income Attributable to Southern Company 33 27  
Total assets 1,517   1,475
Operating Segments | Gas marketing services | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Total operating revenues 285 261  
Other segment items 183 166  
Depreciation and amortization(b) 2 3  
Earnings from equity method investments 0 0  
Interest expense(c) 1 1  
Income taxes (benefit) 28 26  
Consolidated Net Income Attributable to Southern Company 71 65  
Total assets 1,768   1,749
All Other      
Segment Reporting Information [Line Items]      
Total operating revenues 218 229  
Other segment items 190 208  
Depreciation and amortization(b) 17 18  
Earnings from equity method investments 5 (4)  
Interest expense(c) 307 280  
Income taxes (benefit) (77) (75)  
Consolidated Net Income Attributable to Southern Company (214) (206)  
Total assets 2,684   2,829
All Other | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Total operating revenues 2 4  
Other segment items 1 1  
Depreciation and amortization(b) 1 1  
Earnings from equity method investments 0 0  
Interest expense(c) 4 0  
Income taxes (benefit) (10) (9)  
Consolidated Net Income Attributable to Southern Company 6 11  
Total assets 11,276   10,643
Eliminations      
Segment Reporting Information [Line Items]      
Total operating revenues (34) (48)  
Other segment items (40) (58)  
Depreciation and amortization(b) 0 0  
Earnings from equity method investments 0 (1)  
Interest expense(c) 0 0  
Income taxes (benefit) 0 0  
Consolidated Net Income Attributable to Southern Company 6 9  
Total assets (794)   (525)
Eliminations | SOUTHERN Co GAS      
Segment Reporting Information [Line Items]      
Total operating revenues (4) (4)  
Other segment items (4) (4)  
Depreciation and amortization(b) 0 0  
Earnings from equity method investments 0 0  
Interest expense(c) 0 0  
Income taxes (benefit) 0 0  
Consolidated Net Income Attributable to Southern Company 0 $ 0  
Total assets $ (13,121)   $ (11,871)