Fair Value Measurements - SPPC - Level 3 (Details) - Commodity - SPPC - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Fair Value, Assets (Liabilities), Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||
| Beginning balance | $ (15) | $ (19) | $ (11) | $ (13) |
| Changes in fair value recognized in regulatory assets | 0 | (3) | (4) | (10) |
| Settlements | 1 | 0 | 1 | 1 |
| Ending balance | $ (14) | $ (22) | $ (14) | $ (22) |