LEASES - Undiscounted Cash Flows to be Received Under Tolling Arrangements Accounted for as Sales-type Leases (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
2023	$ 39
2024	38
2025	37
2026	36
2027	35
Thereafter	364
Total undiscounted cash flows	549
Lease receivable	326
Difference between undiscounted cash flows and discounted cash flows	223
Other Property and Investments \| Mississippi Power
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
2023	24
2024	23
2025	22
2026	21
2027	20
Thereafter	164
Total undiscounted cash flows	274
Lease receivable	157
Difference between undiscounted cash flows and discounted cash flows	117
Other Current Assets and Net Investment in Sales-type Lease \| Southern Power
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
2023	15
2024	15
2025	15
2026	15
2027	15
Thereafter	200
Total undiscounted cash flows	275
Lease receivable	169
Difference between undiscounted cash flows and discounted cash flows	106
Other current assets \| Southern Power
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
Lease receivable	15	$ 12
Net investment in sales-type leases \| Southern Power
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract]
Lease receivable	$ 154	$ 161

Present value of lease payments not yet received by lessor and amount expected to be derived from underlying asset, following end of lease term guaranteed by lessee or other third party unrelated to lessor, from sales-type and direct financing leases.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=124258985&loc=SL77919391-209981

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 6
-URI https://asc.fasb.org/extlink&oid=124258985&loc=SL77919379-209981

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases.

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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).

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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).

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Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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).

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Amount of undiscounted lease receivable in excess of discounted receivable for sales-type and direct financing leases.

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