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LEASES - Undiscounted Cash Flows to be Received Under Tolling Arrangements Accounted for as Sales-type Leases (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
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Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract] |  |
2024 | $ 38 |
2025 | 37 |
2026 | 36 |
2027 | 35 |
2028 | 34 |
Thereafter | 330 |
Total undiscounted cash flows | 510 |
Lease receivable | 311 |
Difference between undiscounted cash flows and discounted cash flows | 199 |
Other Property and Investments | Mississippi Power |  |
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract] |  |
2024 | 23 |
2025 | 22 |
2026 | 21 |
2027 | 20 |
2028 | 19 |
Thereafter | 145 |
Total undiscounted cash flows | 250 |
Lease receivable | 148 |
Difference between undiscounted cash flows and discounted cash flows | 102 |
Other Current Assets and Net Investment in Sales-type Lease | Southern Power |  |
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract] |  |
2024 | 15 |
2025 | 15 |
2026 | 15 |
2027 | 15 |
2028 | 15 |
Thereafter | 185 |
Total undiscounted cash flows | 260 |
Lease receivable | 163 |
Difference between undiscounted cash flows and discounted cash flows | 97 |
Other current assets | Southern Power |  |
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract] |  |
Lease receivable | 148 | $ 15
Net investment in sales-type leases | Southern Power |  |
Sales-type and Direct Financing Leases, Lease Receivable, Fiscal Year Maturity [Abstract] |  |
Lease receivable | $ 15 | $ 154

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- Definition 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. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 6 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-6 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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- Definition Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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- Definition 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). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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- Definition Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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- Definition Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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- Definition Amount of undiscounted cash flows to be received by lessor for sales-type and direct financing leases 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 Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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- Definition 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). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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- Definition 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). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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- Definition Amount of undiscounted lease receivable in excess of discounted receivable for sales-type and direct financing leases. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 842 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 10 -Publisher FASB -URI https://asc.fasb.org//1943274/2147479773/842-30-50-10 + Details
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