Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions |
6 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Dec. 31, 2016 |
Jun. 30, 2016 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Net cash paid for capitalized interest | $ 72 | $ 89 | $ 128 | ||
| Alabama Power | |||||
| Net cash paid for capitalized interest | 22 | 15 | 11 | ||
| Georgia Power | |||||
| Net cash paid for capitalized interest | 26 | 23 | 20 | ||
| Mississippi Power | |||||
| Net cash paid for capitalized interest | 0 | 29 | 49 | ||
| Southern Power | |||||
| Net cash paid for capitalized interest | 17 | 11 | $ 44 | ||
| Southern Company Gas | |||||
| Net cash paid for capitalized interest | $ 4 | $ 7 | $ 11 | ||
| Southern Company Gas | Southstar | |||||
| Ownership percentage of noncontrolling interest | 15.00% | ||||
| Predecessor | Southern Company Gas | |||||
| Net cash paid for capitalized interest | $ 3 | ||||