Regulatory Matters - Kemper County Energy Facility (Details) - USD ($) $ in Millions |
1 Months Ended | 3 Months Ended | 6 Months Ended | 48 Months Ended | |
|---|---|---|---|---|---|
Dec. 31, 2018 |
Jun. 30, 2019 |
Dec. 31, 2019 |
Jun. 30, 2019 |
Dec. 31, 2023 |
|
| Loss Contingencies [Line Items] | |||||
| Liabilities incurred | $ 6 | ||||
| MISSISSIPPI POWER CO | |||||
| Loss Contingencies [Line Items] | |||||
| Liabilities incurred | 0 | ||||
| MISSISSIPPI POWER CO | Kemper IGCC | |||||
| Loss Contingencies [Line Items] | |||||
| Pre-tax charge to income | $ 4 | 6 | |||
| Asset retirement obligation, liabilities incurred, net of tax | 3 | 5 | |||
| Asset retirement obligation, expected cost | $ 10 | $ 10 | |||
| Government grants received | $ 387 | ||||
| MISSISSIPPI POWER CO | Kemper IGCC | Scenario, Forecast | |||||
| Loss Contingencies [Line Items] | |||||
| Liabilities incurred | $ 7 | ||||
| MISSISSIPPI POWER CO | Kemper IGCC | Minimum | Scenario, Forecast | |||||
| Loss Contingencies [Line Items] | |||||
| Liabilities incurred | $ 2 | ||||
| MISSISSIPPI POWER CO | Kemper IGCC | Maximum | Scenario, Forecast | |||||
| Loss Contingencies [Line Items] | |||||
| Liabilities incurred | $ 6 | ||||