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PROPERTY, PLANT, AND EQUIPMENT - Ownership and Investment in Jointly-Owned Facilities (Details) $ in Millions | 12 Months Ended |
--- | --- | ---
Dec. 31, 2021 USD ($) mi | Sep. 09, 2021
Alabama Power |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 14.00% |
Alabama Power | Greene County (natural gas) Units 1 and 2 |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 60.00% |
Plant in Service | $ 191 |
Accumulated Depreciation | 79 |
CWIP | $ 1 |
Alabama Power | Plant Miller (coal) Units 1 and 2 |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 91.80% |
Plant in Service | $ 2,133 |
Accumulated Depreciation | 665 |
CWIP | $ 15 |
Georgia Power | Plant Hatch (nuclear) |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 50.10% |
Plant in Service | $ 1,382 |
Accumulated Depreciation | 647 |
CWIP | $ 42 |
Georgia Power | Plant Vogtle (nuclear) Units 1 and 2 |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 45.70% |
Plant in Service | $ 3,611 |
Accumulated Depreciation | 2,265 |
CWIP | $ 86 |
Georgia Power | Plant Scherer (coal) Units 1 and 2 |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 8.40% |
Plant in Service | $ 276 |
Accumulated Depreciation | 100 |
CWIP | $ 1 |
Georgia Power | Plant Scherer (coal) Unit 3 |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 75.00% |
Plant in Service | $ 1,314 |
Accumulated Depreciation | 539 |
CWIP | $ 8 |
Georgia Power | Plant Wansley (coal) |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 53.50% |
Plant in Service | $ 1,070 |
Accumulated Depreciation | 472 |
CWIP | $ 7 |
Georgia Power | Rocky Mountain (pumped storage) |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 25.40% |
Plant in Service | $ 184 |
Accumulated Depreciation | 148 |
CWIP | $ 1 |
Mississippi Power | Greene County (natural gas) Units 1 and 2 |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 40.00% |
Plant in Service | $ 124 |
Accumulated Depreciation | 61 |
CWIP | $ 0 |
Mississippi Power | Plant Daniel (coal) Units 1 and 2 |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 50.00% |
Plant in Service | $ 762 |
Accumulated Depreciation | 237 |
CWIP | $ 19 |
Southern Company Gas | Dalton Pipeline (natural gas pipeline) |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership | 50.00% |
Plant in Service | $ 271 |
Accumulated Depreciation | 19 |
CWIP | $ 0 |
Pipeline infrastructure (miles) | mi | 115 |
Agreement to lease undivided ownership (percent) | 50.00% |
Future minimum payments receivable | $ 26 |
Plant Daniel | Mississippi Power |  |
Other Ownership Interests [Line Items] |  |
Percent Ownership |  | 50.00%

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- Definition The period end amount owned by the reporting utility of a jointly owned utility plant in service. + 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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- Definition The period end amount of construction work in progress at a jointly owned electricity generation 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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