PROPERTY, PLANT, AND EQUIPMENT - Ownership and Investment in Jointly-Owned Facilities (Details) $ in Millions	12 Months Ended
Dec. 31, 2025 USD ($) mi	Jul. 15, 2025
Alabama Power
Other Ownership Interests [Line Items]
Percent Ownership	14.00%
Alabama Power \| Plant Greene County (natural gas) Units 1 and 2
Other Ownership Interests [Line Items]
Percent Ownership	60.00%
Plant in Service	$ 190
Accumulated Depreciation	163
CWIP	$ 2
Alabama Power \| Plant Miller (coal) Units 1 and 2
Other Ownership Interests [Line Items]
Percent Ownership	91.80%
Plant in Service	$ 2,181
Accumulated Depreciation	901
CWIP	19
Georgia Power \| Plant Hatch (nuclear) Units 1 and 2
Other Ownership Interests [Line Items]
Plant in Service	1,477
Accumulated Depreciation	593
CWIP	137
Georgia Power \| Plant Vogtle (nuclear) Units 1 and 2
Other Ownership Interests [Line Items]
Percent Ownership		45.70%
Plant in Service	3,598
Accumulated Depreciation	2,326
CWIP	$ 240
Georgia Power \| Plant Vogtle (nuclear) Units 3 and 4
Other Ownership Interests [Line Items]
Percent Ownership	45.70%
Plant in Service	$ 7,979
Accumulated Depreciation	250
CWIP	86
Georgia Power \| Plant Scherer (coal) Units 1 and 2
Other Ownership Interests [Line Items]
Percent Ownership		8.40%
Plant in Service	286
Accumulated Depreciation	152
CWIP	11
Georgia Power \| Plant Scherer (coal) Unit 3
Other Ownership Interests [Line Items]
Percent Ownership		75.00%
Plant in Service	1,323
Accumulated Depreciation	793
CWIP	$ 56
Georgia Power \| Rocky Mountain (pumped storage)
Other Ownership Interests [Line Items]
Percent Ownership	25.40%
Plant in Service	$ 186
Accumulated Depreciation	166
CWIP	$ 18
Mississippi Power \| Plant Greene County (natural gas) Units 1 and 2
Other Ownership Interests [Line Items]
Percent Ownership	40.00%
Plant in Service	$ 119
Accumulated Depreciation	94
CWIP	$ 1
Southern Company Gas \| Dalton Pipeline (natural gas pipeline)
Other Ownership Interests [Line Items]
Percent Ownership	50.00%
Plant in Service	$ 273
Accumulated Depreciation	36
CWIP	$ 1
Pipeline infrastructure (miles) \| mi	115
Agreement to lease undivided ownership (percent)	50.00%
Future minimum payments receivable	$ 26

Jointly Owned Utility Plant, Future Minimum Payments Receivable

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- Definition

Pipeline Infrastructure

+ References

No definition available.

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- Definition

Undivided Ownership Interest To Be Leased

+ References

No definition available.

+ Details

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- Definition

The period end amount owned by the reporting utility of a jointly owned utility plant in service.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 980
-SubTopic 360
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 10.C)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479070/980-360-S99-1

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- Definition

The period end amount of construction work in progress at a jointly owned electricity generation plant.

+ References

+ Details

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- Definition

The period end amount of accumulated depreciation in a jointly owned electricity generation plant.

+ References

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- Definition

The proportionate share of interest (percent) in a jointly owned utility plant.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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