Reportable Segments - Schedule of Interest Income and Expenditures for Long-Lived Assets (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2025 |
Sep. 30, 2024 |
Sep. 30, 2025 |
Sep. 30, 2024 |
|
| Houston Electric | ||||
| Segment Reporting Information [Line Items] | ||||
| Interest income | $ 1 | $ 3 | $ 10 | $ 14 |
| CERC | ||||
| Segment Reporting Information [Line Items] | ||||
| Interest income | $ 0 | $ 1 | $ 10 | $ 2 |