Financing - DOE Loan Guarantee Borrowings (Details) - USD ($) |
12 Months Ended | |||
|---|---|---|---|---|
Dec. 31, 2014 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Sep. 30, 2017 |
|
| Debt Instrument [Line Items] | ||||
| Line of credit facility, maximum borrowing capacity | $ 7,863,000,000 | |||
| Georgia Power | ||||
| Debt Instrument [Line Items] | ||||
| Percent of eligible project costs | 70.00% | |||
| Eligible project costs to be reimbursed | $ 3,460,000,000 | |||
| Basis spread on variable rate | 0.375% | |||
| Line of credit facility, maximum borrowing capacity | 1,750,000,000 | |||
| Amortization period | 5 years | |||
| Georgia Power | Loan Guarantee Agreement | ||||
| Debt Instrument [Line Items] | ||||
| Credit facility conditional borrowing commitment | $ 1,670,000,000 | |||
| Plant Vogtle Units 3 And 4 | Georgia Power | ||||
| Debt Instrument [Line Items] | ||||
| Percent ownership | 45.70% | |||
| FFB Loan | Georgia Power | ||||
| Debt Instrument [Line Items] | ||||
| Line of credit facility, maximum borrowing capacity | $ 2,625,000,000.000 | $ 2,600,000,000.0 |