SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Total AFUDC and Interest Capitalized (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
|
| Capitalized Contract Cost [Line Items] | |||
| Total AFUDC and interest capitalized | $ 339 | $ 400 | $ 327 |
| Alabama Power | |||
| Capitalized Contract Cost [Line Items] | |||
| Total AFUDC and interest capitalized | 76 | 109 | 90 |
| Georgia Power | |||
| Capitalized Contract Cost [Line Items] | |||
| Total AFUDC and interest capitalized | 209 | 251 | 213 |
| Southern Power | |||
| Capitalized Contract Cost [Line Items] | |||
| Total AFUDC and interest capitalized | 7 | 3 | 0 |
| Southern Company Gas | |||
| Capitalized Contract Cost [Line Items] | |||
| Total AFUDC and interest capitalized | $ 47 | $ 37 | $ 24 |