Fair Value Measurements - SPPC - Level 3 (Details) - Commodity - SPPC - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Fair Value, Assets (Liabilities), Net, Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ (33)	$ (52)	$ (13)	$ (33)
Changes in fair value recognized in regulatory assets	(17)	(7)	(37)	(26)
Settlements	14	5	14	5
Ending balance	$ (36)	$ (54)	$ (36)	$ (54)