v3.26.1
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)