INCOME TAXES - Changes in Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Changes in unrecognized tax benefits [Roll Forward]
Beginning balance	$ 116	$ 80	$ 47
Increase from prior periods	10	88	33
Decrease from prior periods	(44)
Ending balance	82	116	80
Estimated loss on plants under construction
Changes in unrecognized tax benefits [Roll Forward]
Statute of limitations expiration		(52)
Georgia Power
Changes in unrecognized tax benefits [Roll Forward]
Beginning balance	77	0	0
Increase from prior periods	0	86	0
Decrease from prior periods	(43)
Ending balance	34	77	0
Georgia Power \| Estimated loss on plants under construction
Changes in unrecognized tax benefits [Roll Forward]
Statute of limitations expiration		(9)
Southern Company Gas
Changes in unrecognized tax benefits [Roll Forward]
Beginning balance	34	32	0
Increase from prior periods	10	2	32
Decrease from prior periods	0
Ending balance	$ 44	34	$ 32
Southern Company Gas \| Estimated loss on plants under construction
Changes in unrecognized tax benefits [Roll Forward]
Statute of limitations expiration		$ 0

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- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 217
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482663/740-10-55-217

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15A
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-Publisher FASB
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 10B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482525/740-10-45-10B

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (a)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-15A

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