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REGULATORY MATTERS - GAS Schedule of Unrecognized Ratemaking Amounts (Details) - Regulatory Asset Off Balance Sheet - USD ($) $ in Millions | Dec. 31, 2021 | Dec. 31, 2020
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Atlanta Gas Light |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Regulatory asset | $ 47 | $ 59
Virginia Natural Gas |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Regulatory asset | 10 | 10
Chattanooga Gas |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Regulatory asset | 4 | 2
Nicor Gas |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Regulatory asset | 0 | 3
Southern Company Gas |  |
Schedule of Regulatory Assets and Liabilities [Line Items] |  |
Regulatory asset | $ 61 | $ 74

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- Definition Schedule of Regulatory Assets and Liabilities. + References No definition available. + Details
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- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
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