Reportable Segments - Narrative (Details) - USD ($) $ in Millions |
9 Months Ended | |
|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
|
| Segment Reporting Information [Line Items] | ||
| Expenditures for Long-lived Assets | $ 3,730 | $ 2,766 |
| Houston Electric | ||
| Segment Reporting Information [Line Items] | ||
| Expenditures for Long-lived Assets | 1,900 | 1,400 |
| CERC | ||
| Segment Reporting Information [Line Items] | ||
| Expenditures for Long-lived Assets | $ 1,100 | $ 1,100 |