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REGULATORY MATTERS - APC Rate ERC (Details) - Alabama Power $ in Millions | 1 Months Ended | 12 Months Ended
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Jan. 31, 2023 $ / KWH_Kilowatt_hour | Dec. 31, 2020 USD ($) $ / KWH_Kilowatt_hour | Oct. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) $ / KWH_Kilowatt_hour | Dec. 31, 2021 USD ($) $ / KWH_Kilowatt_hour | Dec. 31, 2018 $ / KWH_Kilowatt_hour
Schedule of Regulatory Assets and Liabilities [Line Items] |  |  |  |  |  |
Current billing rates under rate ECR (usd per KWH) | $ / KWH_Kilowatt_hour |  | 1.960 |  | 0.02160 | 0.05910 | 0.02353
Current billing rates under rate ECR, percentage decrease |  | 1.84% |  | 1.82% |  |
Current billing rates under rate ECR, decrease, amount |  | $ 103 |  | $ 102 |  |
Reduction of over-collected fuel balance |  |  | $ 94 |  |  |
Over (under) recovered fuel cost |  | $ 18 |  |  | $ (126) |
Rate RSE refund liability, portion attributable to reduce under recovered balance |  |  |  |  | $ 126 |
Scenario, Forecast |  |  |  |  |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |  |  |  |  |
Current billing rates under rate ECR (usd per KWH) | $ / KWH_Kilowatt_hour | 0.05910 |  |  |  |  |

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- Definition Amount of increase (decrease) in obligation to transfer good or service to customer for which consideration has been received or is receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 912 -SubTopic 310 -Section 45 -Paragraph 11 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123371682&loc=d3e55415-109406 + Details
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