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CONSOLIDATED ENTITIES AND EQUITY METHOD INVESTMENTS - GAS Equity Method Investments Narrative (Details) $ in Millions | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2021 USD ($) | Jun. 30, 2021 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2014 mi
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Impairment charges |  |  | $ 2 | $ 0 | $ 168 |
Income taxes (benefit) |  |  | 267 | 393 | 1,798 |
Southern Company Gas |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Impairment charges |  |  | 0 | 0 | 115 |
Income taxes (benefit) |  |  | $ 275 | $ 173 | $ 130 |
Southern Company Gas | PennEast Pipeline |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Ownership percentage, equity method investment |  |  | 20.00% |  |  | 20.00%
Pipeline infrastructure (miles) | mi |  |  |  |  |  | 118
Impairment charges | $ 2 | $ 82 | $ 84 |  |  |
Impairment charges, after tax | $ 2 | $ 58 | 67 |  |  |
Income taxes (benefit) |  |  | $ 7 |  |  |

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- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=123351718&loc=d3e2420-110228 + Details
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