Income Taxes - SPPC - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities	$ 1,290	$ 1,248
Other	649	629
Total deferred income tax assets	3,406	3,400
Property-related items	(12,949)	(12,596)
Regulatory assets	(1,124)	(1,034)
Other	(378)	(491)
Total deferred income tax liabilities	(15,956)	(15,695)
Net deferred income tax liability	(12,628)	(12,437)
SPPC
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities	60	62
Operating and finance leases	24	25
Customer advances	24	16
Derivative contracts and unamortized contract values	3	3
Other	7	5
Total deferred income tax assets	118	111
Property-related items	(379)	(376)
Regulatory assets	(68)	(100)
Operating and finance leases	(24)	(24)
Other	(16)	(15)
Total deferred income tax liabilities	(487)	(515)
Net deferred income tax liability	$ (369)	$ (404)