Revenue from Contracts with Customers and Lease Income - Schedule of Contract Balances (Details) - USD ($) $ in Millions |
Sep. 30, 2023 |
Dec. 31, 2022 |
|---|---|---|
| Disaggregation of Revenue [Line Items] | ||
| Accounts Receivable | $ 2,680 | $ 3,123 |
| Contract Assets | 267 | 156 |
| Contract Liabilities | 62 | 45 |
| ALABAMA POWER CO | ||
| Disaggregation of Revenue [Line Items] | ||
| Accounts Receivable | 858 | 696 |
| Contract Assets | 6 | 2 |
| Contract Liabilities | 0 | 4 |
| GEORGIA POWER CO | ||
| Disaggregation of Revenue [Line Items] | ||
| Accounts Receivable | 1,175 | 922 |
| Contract Assets | 146 | 89 |
| Contract Liabilities | 8 | 9 |
| MISSISSIPPI POWER CO | ||
| Disaggregation of Revenue [Line Items] | ||
| Accounts Receivable | 106 | 92 |
| Contract Assets | 0 | 0 |
| Contract Liabilities | 2 | 0 |
| SOUTHERN POWER CO | ||
| Disaggregation of Revenue [Line Items] | ||
| Accounts Receivable | 138 | 237 |
| Contract Assets | 0 | 0 |
| Contract Liabilities | 8 | 1 |
| SOUTHERN Co GAS | ||
| Disaggregation of Revenue [Line Items] | ||
| Accounts Receivable | 331 | 1,107 |
| Contract Assets | 41 | 0 |
| Contract Liabilities | $ 0 | $ 0 |