Regulatory Matters - APC Certificate of Convenience and Necessity (Details) - USD ($) $ in Millions |
Sep. 30, 2023 |
Dec. 31, 2022 |
Dec. 31, 2020 |
|---|---|---|---|
| Public Utilities, General Disclosures [Line Items] | |||
| Construction work in progress | $ 8,496 | $ 10,896 | |
| Plant in service, net of depreciation | 88,374 | 82,232 | |
| ALABAMA POWER CO | |||
| Public Utilities, General Disclosures [Line Items] | |||
| Construction work in progress | 1,759 | 1,526 | |
| Plant in service, net of depreciation | 23,271 | $ 23,002 | |
| ALABAMA POWER CO | Plant Barry Unit 8 | |||
| Public Utilities, General Disclosures [Line Items] | |||
| Estimated in-service cost | $ 652 | ||
| Construction work in progress | 583 | ||
| Construction in progress, work in progress amount | 578 | ||
| Plant in service, net of depreciation | $ 5 |