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FINANCING - DOE Loan Guarantee Borrowings (Details) - USD ($) | 1 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2020 | Jun. 30, 2020 | Mar. 31, 2019 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Debt Instrument [Line Items] |  |  |  |  |  |
Remaining borrowing capacity |  |  |  | $ 7,594,000,000 |  |
Line of credit facility, maximum borrowing capacity |  |  |  | 7,655,000,000 |  |
Georgia Power |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Percent of eligible project costs (may not exceed) |  |  | 70.00% |  |  |
Remaining borrowing capacity |  |  |  | 1,726,000,000 |  |
Principal amortization payments |  |  |  | 96,000,000 | $ 73,000,000 | $ 0
Line of credit facility, maximum borrowing capacity |  |  |  | $ 1,750,000,000 |  |
Basis spread on variable rate |  |  | 0.375% |  |  |
Amortization period |  |  | 5 years |  |  |
FFB Credit Facility | Georgia Power |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Eligible project costs to be reimbursed |  |  | $ 5,130,000,000 |  |  |
Funds received under guarantee settlement agreement, less customer refunds |  |  | $ 1,492,000,000 |  |  |
Proceeds from lines of credit | $ 69,000,000 | $ 371,000,000 |  |  |  |
Fixed stated interest rate of debt obligation |  | 2.434% |  | 2.178% |  |
Remaining borrowing capacity |  |  |  | $ 0 |  |
Principal amortization payments |  |  |  | 96,000,000 |  |
Line of credit facility, maximum borrowing capacity | $ 4,600,000,000 |  |  | $ 5,000,000,000 | $ 4,600,000,000 |
Plant Vogtle Units 3 and 4 | Georgia Power |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |
Percent ownership |  |  |  | 45.70% |  |
Ownership interest percentage required for voting for continuing construction |  |  |  | 90.00% |  |

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