LEASES - Undiscounted Cash Flows to be Received Under PPAs Accounted for as Operating Leases (Details) $ in Millions	Dec. 31, 2021 USD ($)
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2022	$ 188
2023	139
2024	107
2025	100
2026	99
Thereafter	883
Total	1,516
Alabama Power
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2022	76
2023	32
2024	5
2025	3
2026	3
Thereafter	23
Total	142
Georgia Power
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2022	8
2023	2
2024	0
2025	0
2026	0
Thereafter	0
Total	10
Southern Power
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2022	87
2023	88
2024	90
2025	74
2026	73
Thereafter	240
Total	652
Southern Company Gas
Lessor, Operating Lease, Payments, Fiscal Year Maturity [Abstract]
2022	35
2023	35
2024	33
2025	28
2026	28
Thereafter	407
Total	$ 566

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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919396-209981

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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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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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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).

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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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