Segment Information - SPPC (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) reportableSegment operatingSegment	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | operatingSegment	8
Revenues	$ 26,337	$ 25,150	$ 20,952
Operating income (loss)	5,241	5,327	4,291
Interest expense	2,216	2,118	2,021
Allowance for equity funds	167	126	165
Interest and dividend income	154	89	71
Other, net	(7)	(17)	88
Income (loss) before income tax expense (benefit) and equity income (loss)	1,413	5,294	7,471
Assets	$ 133,840	132,065	127,316
SPPC
Segment Reporting Information [Line Items]
Number of reportable segments | reportableSegment	2
Revenues	$ 1,193	965	854
Operating income (loss)	165	167	165
Interest expense	58	54	56
Allowance for borrowed funds	3	2	2
Allowance for equity funds	7	7	4
Interest and dividend income	18	9	4
Other, net	2	11	7
Income (loss) before income tax expense (benefit) and equity income (loss)	137	142	126
Assets	4,732	4,223	3,919
SPPC | Operating segments
Segment Reporting Information [Line Items]
Operating income (loss)	165	167	165
SPPC | Other
Segment Reporting Information [Line Items]
Assets	67	29	37
SPPC | Regulated electric
Segment Reporting Information [Line Items]
Revenues	1,025	848	738
SPPC | Regulated electric | Operating segments
Segment Reporting Information [Line Items]
Revenues	1,025	848	738
Operating income (loss)	146	148	147
Assets	4,224	3,829	3,540
SPPC | Regulated natural gas
Segment Reporting Information [Line Items]
Revenues	168	117	116
SPPC | Regulated natural gas | Operating segments
Segment Reporting Information [Line Items]
Revenues	168	117	116
Operating income (loss)	19	19	18
Assets	$ 441	$ 365	$ 342