LEASES - Undiscounted Cash Flows to be Received Under PPAs Accounted for as Operating Leases (Details) $ in Millions	Dec. 31, 2025 USD ($)
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2026	$ 119
2027	111
2028	111
2029	116
2030	115
Thereafter	554
Total	1,126
Alabama Power
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2026	6
2027	5
2028	4
2029	4
2030	3
Thereafter	34
Total	56
Southern Power
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2026	148
2027	150
2028	161
2029	164
2030	103
Thereafter	400
Total	1,126
Southern Company Gas
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2026	35
2027	28
2028	28
2029	28
2030	28
Thereafter	299
Total	$ 446

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- Definition

Amount of lease payments to be received by lessor for operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479773/842-30-50-12

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- Definition

Amount of lease payment to be received by lessor for operating lease in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lease payment to be received by lessor for operating lease in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lease payment to be received by lessor for operating lease in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lease payment to be received by lessor for operating lease after fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lease payment to be received by lessor for operating lease in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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- Definition

Amount of lease payment to be received by lessor for operating lease in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

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