Fair Value of Financial Assets and Liabilities (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Disclosures [Abstract]

Gross Notional Amounts of Commodity FTRs

Amounts in Millions (a)	Sept. 30, 2023	Dec. 31, 2022
Megawatt hours of electricity	11	8

(a)Not reflective of net positions in the underlying commodities.

Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level

	Sept. 30, 2023												Dec. 31, 2022
	Fair Value						Fair Value Total		Netting (a)		Total		Fair Value						Fair Value Total		Netting (a)		Total
(Millions of Dollars)	Level 1		Level 2		Level 3								Level 1		Level 2		Level 3
Current derivative assets
Other derivative instruments:
Electric commodity	$	—	$	—	$	63	$	63	$	—	$	63	$	—	$	—	$	119	$	119	$	—	$	119
Total current derivative assets	$	—	$	—	$	63	$	63	$	—	63		$	—	$	—	$	119	$	119	$	—	119
PPAs (b)											3												3
Current derivative instruments											$	66											$	122
Noncurrent derivative assets
PPAs (b)											1												3
Noncurrent derivative instruments											$	1											$	3
Current derivative liabilities
PPAs (b)											4												4
Current derivative instruments											$	4											$	4
Noncurrent derivative liabilities
PPAs (b)											—												2
Noncurrent derivative instruments											$	—											$	2

(a)SPS nets derivative instruments and related collateral on its balance sheet when supported by a legally enforceable master netting agreement. At Sept. 30, 2023 and Dec. 31, 2022, derivative assets and liabilities include no obligations to return cash collateral or rights to reclaim cash collateral.

(b)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.

Changes in Level 3 Commodity Derivatives

	Three Months Ended Sept. 30
(Millions of Dollars)	2023		2022
Balance at July 1	$	83	$	284
Purchases (a)	1		4
Settlements (a)	(18)		(22)
Net transactions recorded during the period:
Net losses recognized as regulatory assets and liabilities (a)	(3)		(32)
Balance at Sept. 30	$	63	$	234
	Nine Months Ended Sept. 30
(Millions of Dollars)	2023		2022
Balance at Jan. 1	$	119	$	27
Purchases (a)	75		241
Settlements (a)	(66)		(116)
Net transactions recorded during the period:
Net (losses) gains recognized as regulatory assets and liabilities (a)	(65)		82
Balance at Sept. 30	$	63	$	234

(a)Relates primarily to FTR instruments administered by SPP.

Carrying Amount and Fair Value of Long-term Debt

	Sept. 30, 2023				Dec. 31, 2022
(Millions of Dollars)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Long-term debt, including current portion	$	3,311	$	2,580	$	3,211	$	2,674

Derivative Instruments, Gain (Loss)

Pre-Tax Fair Value Gains (Losses) Recognized During the Period in:
(Millions of Dollars)	Regulatory Assets and Liabilities
Three Months Ended Sept. 30, 2023
Other derivative instruments
Electric commodity	$	(4)
Total	$	(4)
Nine Months Ended Sept. 30, 2023
Other derivative instruments
Electric commodity	$	(87)
Total	$	(87)
Three Months Ended Sept. 30, 2022
Other derivative instruments
Electric commodity	$	(13)
Total	$	(13)
Nine Months Ended Sept. 30, 2022
Other derivative instruments
Electric commodity	$	80
Total	$	80

Pre-Tax (Gains) Losses Reclassified into Income During the Period from:
(Millions of Dollars)	Regulatory Assets and Liabilities
Three Months Ended Sept. 30, 2023
Other derivative instruments
Electric commodity	6		(a)
Total	$	6
Nine Months Ended Sept. 30, 2023
Other derivative instruments
Electric commodity	78		(a)
Total	$	78
Three Months Ended Sept. 30, 2022
Other derivative instruments
Electric commodity	8		(a)
Total	$	8
Nine Months Ended Sept. 30, 2022
Other derivative instruments
Electric commodity	(26)		(a)
Total	$	(26)