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REGULATORY MATTERS - APC Rate CNP (Details) - Alabama Power - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Schedule of Regulatory Assets and Liabilities [Line Items] |  |  |
Under recovered certified power purchase agreements | $ 84 | $ 58 |
Retail revenue requirement for environmental compliance | 59 | 59 | $ 68
Over (under) recovered environmental clause | $ (16) | $ 28 |

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- Definition Environmental Compliance, Unrecovered Retail Revenue + References No definition available. + Details
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- Definition Over (Under) Recovered Environmental Clause + References No definition available. + Details
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- Definition Schedule of Regulatory Assets and Liabilities. + References No definition available. + Details
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- Definition Under Recovered Certified Power Purchase Agreements + References No definition available. + Details
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- Details
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