Recurring Fair Value Measurements (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Derivative Asset, Net		$ 3	$ 6
Derivative Liability, Current		4	4
Derivative Liability, Net		2	6
Return Cash Collateral		0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Derivative Asset, Current		$ 122	$ 30
Derivative Asset, Noncurrent, Statement of Financial Position [Extensible Enumeration]		Derivative instruments	Derivative instruments
Commodity Contract [Member]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at beginning of period		$ 27	$ 7	$ 12
Purchases	[1]	248	10	23
Settlements	[1]	(168)	(79)	(23)
Gains (losses) recognized as regulatory assets	[1]	12	89	(5)
Balance at end of period		119	27	$ 7
Fair Value Measured on a Recurring Basis
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Derivative Asset, Current		119	27
Fair Value Measured on a Recurring Basis | Other Derivative Instruments | Electric Commodity Contract
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Derivative Asset, Current		119	27
Fair Value Measured on a Recurring Basis | Other Current Assets
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		119	27
Netting	[2]	0	0
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0	0
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0	0
Fair Value Measured on a Recurring Basis | Other Current Assets | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		119	27
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Electric Commodity Contract
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		119	27
Netting	[2]	0	0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Electric Commodity Contract | Level 1
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0	0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Electric Commodity Contract | Level 2
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		0	0
Fair Value Measured on a Recurring Basis | Other Current Assets | Other Derivative Instruments | Electric Commodity Contract | Level 3
Derivatives, Fair Value [Line Items]
Derivative Asset, Gross		119	27
Fair Value, Measurements, Nonrecurring | Purchased Power Agreements
Derivatives, Fair Value [Line Items]
Derivative Asset, Net	[3]	3	6
Derivative Liability, Current	[3]	4	4
Derivative Liability, Net	[3]	2	6
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Derivative Asset, Current	[3]	$ 3	$ 3

[1] Relates primarily to FTR instruments administered by SPP.

[2] SPS nets derivative instruments and related collateral on its balance sheet when supported by a legally enforceable master netting agreement. At Dec. 31, 2022 and 2021, derivative assets and liabilities include no obligations to return cash collateral or rights to reclaim cash collateral. Counterparty netting amounts presented exclude settlement receivables and payables and non-derivative amounts that may be subject to the same master netting agreements.

[3] SPS currently applies the normal purchase exception to qualifying PPAs. Balance relates to specific contracts that were previously recognized at fair value prior to applying the normal purchase exception, and are being amortized over the remaining contract lives along with the offsetting regulatory assets and liabilities.