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REGULATORY MATTERS - GPC Joint Ownership Agreements (Details) - Georgia Power - USD ($) $ in Millions | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Mar. 31, 2019 | Dec. 31, 2021 | Dec. 31, 2021 | Dec. 31, 2015
Public Utilities, General Disclosures [Line Items] |  |  |  |
Amortization period | 5 years |  |  |
Pre-tax charge to income |  | $ 440 |  |
After tax charge to income |  | $ 328 |  |
Plant Vogtle Units 3 and 4 |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Ownership interest percentage required for voting for continuing construction |  | 90.00% | 90.00% |
Production tax credits, aggregate purchase price (up to) |  |  | $ 300 |
Preliminary estimated cost to complete |  | $ 10,401 | 10,401 |
Additional construction capital costs |  |  | $ 460 | $ 3,300
Remaining share of construction costs, agreement to pay, percentage |  |  | 100.00% |
Percentage of costs, disallowed for recovery |  |  | 6.00% |
Costs disallowed for recovery, period |  |  | 6 months |
Public utilities, extension project schedule, term |  |  | 1 year |
Estimated cost to complete, starting dollar amount |  | $ 18,380 | $ 18,380 |
Percent ownership |  | 45.70% | 45.70% |
Plant Vogtle Units 3 and 4 | Minimum |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Global amendments, tender provision, decision period after tender option triggered |  |  | 120 days |
Plant Vogtle Units 3 and 4 | Maximum |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Global amendments, tender provision, decision period after tender option triggered |  |  | 180 days |
Plant Vogtle Units 3 and 4 | Category I |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Preliminary estimated cost to complete |  | $ 8,400 | $ 8,400 |
Additional construction capital costs, threshold |  |  | $ 800 |
Plant Vogtle Units 3 and 4 | Category II |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Percentage of construction costs responsible to pay |  |  | 55.70% |
Additional construction capital costs |  |  | $ 80 |
Plant Vogtle Units 3 and 4 | Category II | Vogtle Owners |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Percentage of construction costs responsible to pay |  |  | 44.30% |
Plant Vogtle Units 3 and 4 | Category II | Minimum |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Additional construction capital costs, threshold |  |  | $ 800 |
Plant Vogtle Units 3 and 4 | Category II | Maximum |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Additional construction capital costs, threshold |  |  | $ 1,600 |
Plant Vogtle Units 3 and 4 | Category III |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Percentage of construction costs responsible to pay |  |  | 65.70% |
Additional construction capital costs |  |  | $ 100 |
Plant Vogtle Units 3 and 4 | Category III | Vogtle Owners |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Percentage of construction costs responsible to pay |  |  | 34.30% |
Plant Vogtle Units 3 and 4 | Category III | Maximum |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |
Additional construction capital costs, threshold |  |  | $ 2,100 |

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