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REGULATORY MATTERS - APC Accounting Orders and Plant Greene County (Details) - USD ($) $ in Millions | Dec. 31, 2021 | Sep. 09, 2021 | Dec. 31, 2020
--- | --- | --- | ---
Public Utilities, General Disclosures [Line Items] |  |  |
Other deferred charges and assets | $ 17,259 |  | $ 16,298
Alabama Power |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Other deferred charges and assets | $ 4,549 |  | 4,262
Percent ownership | 14.00% |  |
Alabama Power | Software Accounting Order |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Other deferred charges and assets | $ 35 |  | 17
Mississippi Power |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Other deferred charges and assets | $ 877 |  | $ 805
Mississippi Power | Plant Greene County Units 1 and 2 |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |
Percent ownership |  | 40.00% |

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- Definition Sum of the carrying amounts as of the balance sheet date of all assets, excluding Property, Plant, and Equipment and Other Property and Investments, that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer. + References No definition available. + Details
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- Definition The proportionate share of interest (percent) in a jointly owned utility plant. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
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