| Line Item | Sep 30, 2024 | Sep 30, 2023 | Sep 30, 2021 | Mar 31, 2021 | Sep 30, 2020 | Mar 31, 2020 | Mar 31, 2019 |
|---|---|---|---|---|---|---|---|
| Operating Revenues: | |||||||
| Total operating revenues | |||||||
| Operating Expenses: | |||||||
| Total cost of sales | — | ||||||
| Other operations and maintenance | |||||||
| Depreciation and amortization | |||||||
| Taxes other than income taxes | |||||||
| Estimated loss on Plant Vogtle Units 3 and 4 | |||||||
| Total operating expenses | |||||||
| % of revenue | 67.4% | ||||||
| Operating Income | |||||||
| % of revenue | 32.6% | ||||||
| Other Income and (Expense): | |||||||
| Allowance for equity funds used during construction | |||||||
| Earnings from equity method investments | |||||||
| Interest expense, net of amounts capitalized | |||||||
| Other income (expense), net | |||||||
| Total other income and (expense) | |||||||
| Earnings Before Income Taxes | |||||||
| Income taxes | |||||||
| Consolidated Net Income | |||||||
| % of revenue | 21.1% | ||||||
| Net income (loss) attributable to noncontrolling interests | |||||||
| Consolidated net income attributable to company | |||||||
| Basic (in dollars per share) | |||||||
| Diluted (in dollars per share) |