Income Taxes - SPPC - Components of Net Deferred Income Tax Liability (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities	$ 1,349	$ 1,420
Other	686	777
Total deferred income tax assets	3,159	3,178
Property-related items	(11,814)	(10,816)
Regulatory assets	(764)	(785)
Other	(478)	(327)
Total deferred income tax liabilities	(15,933)	(14,749)
Net deferred income tax liability	(12,938)	(11,775)
SPPC
Deferred Tax Assets and Liabilities [Line Items]
Regulatory liabilities	64	67
Operating and finance leases	27	30
Customer advances	14	10
Derivative contracts and unamortized contract values	8	2
Other	6	8
Total deferred income tax assets	119	117
Property-related items	(379)	(380)
Regulatory assets	(94)	(74)
Operating and finance leases	(27)	(30)
Other	(21)	(7)
Total deferred income tax liabilities	(521)	(491)
Net deferred income tax liability	$ (402)	$ (374)