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LEASES - Lease Income (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Lessor, Lease, Description [Line Items] |  |  |
Lease income - interest income on sales-type leases | $ 15 | $ 16 | $ 9
Lease income - operating leases | 223 | 208 | 273
Variable lease income | 429 | 419 | 403
Total lease income | 667 | 643 | 685
Alabama Power |  |  |
Lessor, Lease, Description [Line Items] |  |  |
Lease income - interest income on sales-type leases | 0 | 0 | 0
Lease income - operating leases | 82 | 45 | 24
Variable lease income | 0 | 0 | 0
Total lease income | 82 | 45 | 24
Georgia Power |  |  |
Lessor, Lease, Description [Line Items] |  |  |
Lease income - interest income on sales-type leases | 0 | 0 | 0
Lease income - operating leases | 42 | 58 | 71
Variable lease income | 0 | 0 | 0
Total lease income | 42 | 58 | 71
Mississippi Power |  |  |
Lessor, Lease, Description [Line Items] |  |  |
Lease income - interest income on sales-type leases | 14 | 12 | 9
Lease income - operating leases | 2 | 2 | 0
Variable lease income | 0 | 0 | 0
Total lease income | 16 | 14 | 9
Southern Power |  |  |
Lessor, Lease, Description [Line Items] |  |  |
Lease income - interest income on sales-type leases | 1 | 0 | 0
Lease income - operating leases | 85 | 87 | 160
Variable lease income | 456 | 449 | 434
Total lease income | 542 | 536 | 594
Southern Company Gas |  |  |
Lessor, Lease, Description [Line Items] |  |  |
Lease income - interest income on sales-type leases | 0 | 0 | 0
Lease income - operating leases | 35 | 35 | 35
Variable lease income | 0 | 0 | 0
Total lease income | $ 35 | $ 35 | $ 35

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- Definition Amount of lease income from operating, direct financing, and sales-type leases. Includes, but is not limited to, variable lease payments, interest income, profit (loss) recognized at commencement, and lease payments paid and payable to lessor. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919372-209981 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919372-209981 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123420820&loc=SL77919311-209978 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 50 -Paragraph 6A -URI http://asc.fasb.org/extlink&oid=124502072&loc=SL77927221-108306 + Details
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- Definition Amount of interest income from net investment in sales-type lease. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 5 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919372-209981 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 50 -Paragraph 6A -URI http://asc.fasb.org/extlink&oid=124502072&loc=SL77927221-108306 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 25 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123408481&loc=SL77919101-209958 + Details
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- Definition Amount of variable lease payments from operating, direct financing, and sales-type leases, excluding amount included in measurement of lease receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919372-209981 + Details
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- Details
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